As part of the natural resource management (NRM) the exploitation and assessment of water resources from melted snow, the snow water equivalent (SWE) for hydro power generation can proceed only by remote sensing. The evaluation algorithm EQeau is already introduced for this assessment. This connects the remotely data to the SWE exploiting the seasonal thermal resistance change of the soil and snow cover. On the other hand this technique needs representative vicarious ground calibrations, especially that of the snow density. At this end the devices used for the ground truth measurements are too small in comparison with a remote sensing pixel size and are not suitable for continous monitoring. The new method and device senses a more than 50 times larger measuring volume than the usual ones, its linear extension can be compared by a pixel side. The sensor is an unshielded flat band cable which will be embedded by snow fall and remains and measures there during the entire winter season. With time domain reflectometry (TDR) and low frequency measurements on this long sensor one can determine the density, the most important input for the calibration of the remotely sensed data. The method contributes to a better prognoses for avalanche and flood warning as well, because it measures the snow liquid water content also. The method and instrument are installed in four consecutive winter seasons.

GPS signals reflected from the ocean surface have been used in remote sensing applications to determine sea-state and wind speed. Studies show that, with rougher surfaces, GPS signal pulses scatter more, which creates weaker and wider pulses at the receiver. Based on this model, the correlation between soil moisture, topography, and GPS signals was studied using reflections off the ground. The data used for the study were gathered during two flights in 1998 and 2001 around Austin, Texas and Albuquerque, New Mexico and later processed at Langley Research Center. The power of the signals were analyzed and plotted over Digital Elevation Models (DEMs) and Landsat7 images (near- and mid-infrared bands) to interpret the correlation of signal behavior with topography. In addition, the received signal's conduct was correlated with soil moisture data obtained from the Department of Agriculture's Soil Climate Analysis Network (SCAN) sites at Prairie View (Texas) and Adams Ranch (New Mexico). The strengths of the reflected signals were observed larger near known bodies of water and farmlands where soil moisture levels are known to be high. In general, for flat lands, the power of the signals and soil moisture contents appeared to have a close-to-linear relationship. In addition, the received pulses widened when reflected over rapid-changing topography in Texas, but any relationship among these was not perceived in New Mexico. Further studies are needed to obtain a definite relationship among soil moisture and reflected signal strength and to introduce satellite position in the signal-topography study.

A correct urban and land-use planning can be supported by several innovative tools and methodologies. In this paper the potential of remote sensing and GIS technologies have been emphasized. The proposed methodology has been applied to the River Pescara Valley, considered as the appropriate coverage in order to define environmental features that influence the industrial areas. For this research MIVIS hyperspectral (at 1500 and 3000 m of elevation) sensor images have been used. The obtained images have been georeferenced. From the processing and classification of these images some information layer have been obtained: thematic maps of land-use (industrial areas identification), vegetation conditions, thermal pollution, quality parameters (temperature, organic matter, chlorophyll, sediments) for river and sea waters. Thematic maps obtained from remote sensing have been inserted in a GIS, that means a system to insert, store, integrate, extract, retrieve, manipulate and analyze georeferenced data layers in order to produce interpretable information. Then the data base has been integrated with further information inserted as continuous layers; thematic layers; vector layers; punctual data; attributes. Some specific operators have been applied that allowed to integrate the information contents and therefore to obtain final thematic maps (environmental quality maps, vulnerability and risk maps, visualization of models related to accidental events). The innovative technologies proposed facilitate and optimize the duties required from actual regulations, as for a recent Italian regulation aimed to the verification and research of compatibility of major hazard industrial plants with land-use and environment. Therefore it is useful to develop methodologies supporting industry and Competent Authorities.

The Ozone and Pollution measuring Ultraviolet Spectrometer (OPUS) is scheduled to launch on board the GCOM A1 satellite, to measure ozone, sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and other chemical species including aerosols. OPUS measures the backscattered ultraviolet radiance with the wavelength step of 0.5 nm in ultraviolet-near infrared regions. This wavelength step is coarse compared with that of GOME, but it was found that this difference do not substantially affect the uncertainty in SO₂ estimation. Simulation study using the radiative transfer code of MODTRAN reveals that the wavelength range of 310 - 320 nm was found to be sensitive for SO₂ detection in case of solar backscattered radiation measurements from space. We will present the estimation method of total column SO₂ amount from the backscattered radiance observed with OPUS, using the fine structure of SO₂ absorption spectrum.

Yigong(Yig.) Landslide occurred at 20:00, 04/09/2000 in Zhamulong(Zha.) Gully located in the southern-east part of Tibet in China. The huge rock collapse -- landslide occurred at first in the upper part of Zha. Gully, then that immediately changed into debris-flow and rush down for about 8 km, in two or three minutes, blocked the Yig. River course and formed a plateau lake -- Yig. Lake, the natural dam covered about 4.5 km², with a 3 x 10⁸m³ of volume. At 21:30, 06/10/2000, Yig. Landslide dam burst, about 22 x 10⁸m³ of torrent pour down lower reach causing serious economic loss and ecologic disaster. By satellite remote sensing technique, the process from Yig. Landslide occurrence to after the Yig. Lake burst, had been monitored, and proper prediction was made.

ACE is a Canadian satellite mission that will measure and help to understand the chemical and dynamical processes that control the distribution of ozone in the stratosphere. The ACE instruments are a Fourier transform infrared spectrometer, a UV/visible/near IR spectrograph and a two channel solar imager, all working in solar occultation mode.

Scisat-1, otherwise known as the Atmospheric Chemistry Experiment, is a satellite mission designed for remote sensing of the Earth's atmosphere using occultation spectroscopy. The primary goal of the mission is to investigate the chemical and dynamical processes that govern ozone distribution in the stratosphere and upper troposphere. It has been developed under the auspices of the Canadian Space Agency and is scheduled for launch in December of 2002. The primary instrument on board Scisat-1 is a high resolution Fourier transform spectrometer (FTS) operating in the infrared. Pressure and temperature as a function of altitude will be determined from the FTS measurements through analysis of carbon dioxide absorption. Volume mixing ratio (vmr) profiles will be retrieved for more than thirty molecules of atmospheric interest. Both the pressure/temperature and vmr retrievals use non-linear least squares Global Fit type approaches. For the pressure/temperature analysis, several variations are being developed; the choice of which version to implement depends on the quality of the pointing information obtained from the satellite. In the case of poor pointing knowledge, tangent height separations between measurements will be determined directly from the FTS data (simultaneously with the pressure and temperature determination) through the imposition of hydrostatic equilibrium.

The feasibility of using nadir observations to make column measurements of several stratospheric gases will be evaluated for the Atmospheric Chemistry Experiment (ACE) Fourier-transform spectrometer (FTS), which is scheduled for launch in 2002 on the SCISAT-1 platform. The measurement technique is based on using FTIR spectroscopy to measure the atmospheric absorption of cold gases below the satellite against the thermal emission background from the warm earth. The FASCOD3 and MODTRAN4 transmission codes are used to simulate the background emission spectra above the earth; the measured spectra are processed to yield the column concentration of a particular gas in the atmosphere. The gases that can be successfully measured with this technique include ozone, carbon dioxide, carbon monoxide, methane and nitrous oxide. This technique will be demonstrated for nadir IMG spectra obtained in 1997 at a resolution of 0.1 cm^-1. Since ACE points at the sun throughout its orbit, even when the earth is in the way, nadir FTS measurements will automatically be taken in addition to the occultation measurements, if enough power is available. A nadir observation will consist of 100 co-added scans at a resolution of 0.4 cm^-1, which will require a total time of 16 seconds and achieve a signal-to-noise ratio of 80:1. Using the spectroscopic structure obtained from nadir IMG spectra at a resolution of 0.1 cm^-1 over an extended spectral interval, it will be demonstrated that a signal-to-noise ratio of 50:1 gives ozone columns with an error of less than 2%.

The Atmospheric Chemistry Experiment (ACE) is the mission selected by the Canadian Space Agency for its next science satellite, SCISAT-1. ACE consists of a suite of instruments in which the primary element is an infrared Fourier Transform Spectrometer (FTS) coupled with an auxiliary 2-channel visible (525nm) and near infrared imager (1020nm). A secondary instrument, MAESTRO, provides spectrographic data from the near ultra-violet to the near infrared, including the visible spectral range. In combination the instrument payload covers the spectral range from 0.25 to 13.3 micron. A comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols and temperature will be made by solar occultation from a satellite in low earth orbit. The ACE mission will measure and analyse the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere. A high inclination (74 degrees), low earth orbit (650 km) allows coverage of tropical, mid-latitude and polar regions. This paper describes the detailed design of the ACE-FTS instrument. The principal design drivers and trade-offs are covered as well as system engineering approaches to optimise the performance of the instrument. Its highly folded, compact and robust opto-mechanical design is described. The structural and thermal design challenges, which have considerably impacted the detailed design of the instrument, are presented. Lessons learned during the detailed design phase and manufacturing of the Flight Model are presented. The latest status of the flight model is also presented as well as preliminary test results.

The Atmospheric Chemistry Experiment (ACE) is the mission selected by the Canadian Space Agency for its next science satellite, SCISAT-1. ACE consists of a suite of instruments in which the primary element is an infrared Fourier Transform Spectrometer (FTS) coupled with an auxiliary 2-channel visible (525 nm) and near infrared imager (1020 nm). A secondary instrument, MAESTRO, provides spectrographic data from the near ultra-violet to the near infra-red, including the visible spectral range. In combination the instrument payload covers the spectral range from 0.25 to 13.3 microns. A comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols and temperature will be made by solar occultation from a satellite in low earth orbit. The ACE mission will measure and analyze the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere. A high inclination (74°), low earth orbit (650 km) allows coverage of tropical, mid-latitude and polar regions. This paper describes the test activities around the ACE-FTS Flight Model (FM) and the preliminary results obtained. It also presents the expected performances of the instrument in terms of key parameters like signal-to-noise ratio and resolution.

SCISAT-1, the Atmospheric Chemistry Experiment, will use the solar occultation technique to make measurements of trace gases, atmospheric extinction, temperature, and pressure in the stratosphere and upper troposphere. The accuracy and reliability of the ACE results will be demonstrated through a validation program including ground-, balloon-, and satellite-based observations. This program will be ongoing throughout the lifetime of the mission. To provide sufficient global coverage, a worldwide group of participants will be collaborating with the ACE Validation team. Descriptions and locations of the validation experiments are given.

The Atmospheric Chemistry Experiment (ACE) is the mission selected by the Canadian Space Agency for its next science satellite, SCISAT-1. ACE consists of a suite of instruments in which the primary element is an infrared Fourier Transform Spectrometer (FTS) coupled with an auxiliary 2-channel visible (525 nm) and near infrared imager (1020 nm). A secondary instrument, MAESTRO, provides spectrographic data from the near ultraviolet to the near infrared, including the visible spectral range. In combination, the instrument payload covers the spectral range from 0.25 to 13.3 micron. A comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols and temperature will be made by solar occultation from a satellite in low earth orbit. The ACE mission will measure and analyze the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere. A high inclination (74°), low earth orbit (650 km) allows coverage of tropical, mid-latitude and polar regions. This paper will describe level 1 algorithms that are needed on ground in order to produce meaningful data meeting all requirements of the ACE FTS instrument. Level 0 data are as downlinked from the spacecraft. Level 1A data are decoded (CCSDS, bit trim) interferograms from individual acquisition channels. Level 1B data are made of spectrally (spatial frequency) calibrated transmittances with annotated quality indicators. Some key ACE FTS L1B algorithms include, non-linearity characterization/correction, robust interferometer fringe count error handling, spectral calibration from Solar reference lines, transmittance computation with phase error correction, and correction of the instrument line shape (ILS) distortion.

The Ozone Mapping and Profiler Suite (OMPS) is being developed for the United States National Polar-orbiting Operational Environmental Satellite System (NPOESS). We describe the optical design and predict the performance of the OMPS nadir-looking imaging spectrometer. Backscattered solar ultraviolet radiation is dispersed and measured to determine the ozone total column amounts and profile concentrations. The sensor consists of a wide field (110 degree) telescope, with a solar-diffuser calibration mechanism, and two spectrometers: an imager covering 300 to 380 nm with a 50 km nadir footprint for mapping total column ozone across a 2800 km swath, and a 250 to 310 nm spectrometer with a single 250 km footprint to provide ozone profile data with SBUV/2 heritage. Both spectrometers provide 1 nm resolution (full-width at half-maximum, FWHM) spectra and handle the demanding dynamic range of the backscattered solar radiation with the required sensitivity for ozone retrievals.

The Ozone Mapping and Profiler Suite (OMPS) is being developed for the United States National Polar-orbiting Operational Environmental Satellite System (NPOESS). We describe the optical design and predict the performance of the OMPS earth limb-imaging spectrometer. Limb-scattered solar radiation is measured at selected ultraviolet (UV), visible, and near infrared (NIR) wavelengths to determine ozone profile concentrations for the altitude range of 8 to 60 km. The sensor consists of a telescope with three separate crosstrack fields of view of the limb, a prism spectrometer covering 290 to 1050 nm, and a solar-diffuser calibration mechanism. The sensor provides 3 km vertical resolution profiles of atmospheric radiance with channel spectral resolutions (full-width at half-maximum, FWHM) ranging from 2.7 nm in the UV to 35 nm in the NIR and handles the demanding spectral and spatial dynamic range of the limb-scattered solar radiation with the required sensitivity for ozone retrievals.

Since 1995 the Global Ozone Monitoring Experiment (GOME) is measuring ozone (total column and profile), nitrogen dioxide and other minor trace gases on-board of the European Space Agency (ESA) ERS-2 satellite. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and ESA decided to fly an advanced GOME-2 instrument on the METOP satellites. The GOME-2 measurements will provide the input for the ozone data record in the timeframe 2005 to 2020 provided by the EUMETSAT Polar System (EPS). The radiometric calibration of the polarisation sensitive GOME-2 instrument is significantly improved by the simultaneous measurement of s- and p -polarised light at moderate resolution and high temporal resolution. The Polarisation Monitoring Device (PMD) measures the spectral range between 312 and 790 nm in 15 narrow bands. The ground pixel size in the 960 km swath is 40 x 5km². The paper describes in detail the polarisation measurement devices and their technical capabilities.

The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Visible and Infrared Imager/Radiometer Suite (VIIRS) has responsibility for 23 Environmental Data Recrods (EDRs), three of them key NPOESS EDRs of highest value to opertional users: Imagery, Sea Surface Temrpature (SST), and Soil Moisture (primary EDR from the NPOESS conical microwave imager/sounder [CMIS]). The VIIRS design was guided by a set of government requirements priorities, which were topped by key EDR performance. Taking advantage of the MODerate-resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field Sensor (SeaWiFs) heritage, Raytheon's challenge was to optimize VIIRS system performance using Cost As Independent Variable (CAIV) analyses. The SST key EDR solution combines the traditional long-wave infrared (LWIR) split window with a second split window in the mid-wave infrared (MWIR) 3-4 μm region to offer a globally robust "dual split-window" SST algorithm operable daytime and nighttime with a precision of 0.25 K, and an overall uncertainty of 0.35 K (intermediate objective) across the entire SST measurement range. This capability was recently validated by the heritage MODIS on NASA's Terra satellite. The imagery key EDR solution permits superb multi-spectral detection and discrimination of cloud presence and type MODIS. The soil moisture solution is a cross-sensor fusion approach that combines the finer spatial resolution of VIIRS with traditional coarse resolution microwave-derived soil moisture retrievals to achieve objectives under open and partially vegetated scenes. This paper briefly describes the VIIRS sensor design, the key EDR performance, and the CAIV design process with three specific hardware and EDR tradeoff exmaples. Finally, the paper concludes with a description of the key risk-reduction design processes that led to a relativley low-risk (for advanced space-borne hardware programs) developmental design, which is now approaching hardware realization.

The Japanese Advanced Meteorological Imager (JAMI) introduces next generation technology geosynchronous earth orbit (GEO) imagers for operational meteorological remote sensing. Raytheon Santa Barbara Remote Sensing is building JAMI for Space Systems/Loral as the imager subsystem for Japan's MTSAT-1R system. JAMI represents the best balance between heritage and newer space-qualified technology and meets all Japan Ministry of Transport MTSAT requirements from beginning to end of life with considerable margin, using a simple, inherently low risk design. The advanced technology built into this imager benefits operational meteorological imaging for Japan, East Asia and Australia by enabling significantly better radiometric sensitivity and absolute accuracy, higher spatial resolution and faster full disk coverage times than available from current GEO imagers. JAMI is on schedule for an on time or early delivery to Space Systems/Loral.

This paper describes the Topsat satellite programme, focussing on the key technical, operational and commercial aspects of the mission. Topsat is designed to demonstrate the capabilities of small satellites for classically high value remote sensing missions. Topsat is a 120kg, sun-synchronous satellite, designed to provide 2.5m resolution imagery direct to users in the locale of the imaged area. It is an end-to-end mission encompassing development, build, launch, operation and exploitation. Its objectives are to demonstrate the capability to cost performance available from small satellites and the utility of direct tasking and reception of remotely sensed imagery. It is expected that Topsat will be exploited both through its imagery and through the demonstration of affordability of constellations and individually owned assets. The paper provides an overview of the mission and an update to the status of the mission as of July 2002.

This paper explores the relationships between optical imagery performance metrics, and the requirements they place on the attitude control, and orbital knowledge, of a small, low cost, optical remote sensing satellite. These relationships are illuminated by the very real decisions and trade offs encountered in the design and development of the Topsat satellite. Topsat is a small, sun-synchronous satellite, designed to provide 2.5m resolution panchromatic imagery and 5m multispectral imagery in the three visible wavebands.

The Imagers and the Sounders on the present generation of GOES spacecraft each have a full-aperture blackbody for on-board infrared (IR) calibration. Each instrument interrupts its Earth-viewing operations at regular intervals and views this blackbody by rotating its scan mirror. IR Radiation from this blackbody follows the same path through the entire optical train as radiation from the Earth. The instrument also observes space to measure background generated by the instrument. The difference between signals from the blackbody and from space is used in conjunction with the measured temperature of the blackbody to compute the gain for each IR channel of the instrument. The GIFTS is an experimental, next-generation IR sounder with a Michelson interferometer. It performs on-board gain calibration by sequentially viewing two internal blackbodies that operate at different temperatures, measuring the difference between the resultant signals. A flip mirror is used to insert the blackbodies into the optical beam after the beam has been converged by the telescope. The apertures of the GIFTS blackbodies are much smaller than that of the telescope. This approach allows the blackbodies to have deep cavities and minimizes the time lag and the momentum disturbance in the calibration process. On the other hand, GIFTS is unable to directly measure long-term changes in the throughput of the optical elements that are not included in the calibration path: the scan mirror and two telescope mirrors. The GIFTS approach is capable of high radiometric precision, but requires augmentation by occasional end-to-end IR calibration measurements to achieve the required absolute accuracy over the lifetime of an operational GOES mission.

The GOES Imager and Sounder instruments each observe the full Earth disk, 17.4° in diameter, from geostationary orbit. Pre-launch, each instrument's dynamic scanning performance is tested using the projection of a test pattern from a wide-field collimator. We are fabricating a second wide-field collimator (WFC2) to augment this test program. The WFC2 has several significant advantages over the existing WFC1. The WFC2 target illumination system uses an array of light-emitting diodes (LEDs) radiating at 680nm, which is within the visible bands of both the Imager and Sounder. The light from the LEDs is projected through a non-Lambertian diffuser plate and the target plate to the pupil of the projection lens. The WFC2's power dissipation is much lower than that of WFC1, decreasing stabilization time and eliminating the need for cooling fans. The WFC2's custom-designed 5-element projection lens has the same effective focal length (EFL) as the WFC1 projection lens. The WFC2 lens is optimized for the LED's narrow spectral band simplifying the design and improving image quality. The target plate is mounted in a frame with a mechanized micro-positioner system that controls three degrees of freedom: tip, tilt, and focus. The tip and tilt axes intersect in the WFC's image plane, and all adjustments are controlled remotely by the operator observing the target plate through an auto-collimating telescope.

The Remote Sensing Group at the University of Arizona uses Spectralon^TM (a sintered polytetraflouroethylene-based material) as a white reference source for ground based measurements used in vicarious calibration. These Spectralon panels degrade spectrally and angularly over time due to use in harsh field conditions with their reflectance falling off at shorter wavelengths. This paper examines the effects of sanding on the bi-directional reflectance of Spectralon using measurements in the Remote Sensing Group's calibration lab. The objective is to determine whether the near-Lambertian and spectrally flat nature can be restored through wet sanding with wet/dry sandpaper and de-ionized water. The reference for this method is the hemispherical reflectance of pressed polytetrafluoroethylene (PTFE) powder prepared according to National Institute of Standards and Technology (NIST) directions. The panels and a radiometer are mounted on rotation stages to measure the reflectance factor at different incidence angles for a normal view angle. These measurements are repeated for different panel alignments. Sanding techniques are examined using several grit sizes and strokes.

The recognized need for on-orbit calibration of remote sensing imaging instruments drives the ROLO project effort to characterize the Moon for use as an absolute radiance source. For over 5 years the ground-based ROLO telescopes have acquired spatially-resolved lunar images in 23 VNIR (Moon diameter ≈500 pixels) and 9 SWIR (≈250 pixels) passbands at phase angles within ±90 degrees. A numerical model for lunar irradiance has been developed which fits hundreds of ROLO images in each band, corrected for atmospheric extinction and calibrated to absolute radiance, then integrated to irradiance. The band-coupled extinction algorithm uses absorption spectra of several gases and aerosols derived from MODTRAN to fit time-dependent component abundances to nightly observations of standard stars. The absolute radiance scale is based upon independent telescopic measurements of the star Vega. The fitting process yields uncertainties in lunar relative irradiance over small ranges of phase angle and the full range of lunar libration well under 0.5%. A larger source of uncertainty enters in the absolute solar spectral irradiance, especially in the SWIR, where solar models disagree by up to 6%. Results of ROLO model direct comparisons to spacecraft observations demonstrate the ability of the technique to track sensor responsivity drifts to sub-percent precision. Intercomparisons among instruments provide key insights into both calibration issues and the absolute scale for lunar irradiance.

Over the past 4 years, we have developed and extensively deployed the Calibrated, InfraRed, In situ Measurement System, or CIRIMS, for at-sea validation of satellite-derived sea surface temperature (SST). The project is funded by the NASA EOS Validation Program for validation of SST from MODIS, the MODerate resolution Imaging Spectroradiometer, aboard the EOS Terra and Aqua satellites. The design goals include autonomous operation at sea for up to 6 months and an accuracy of ±0.1°C. One of the most challenging aspects of the design is protection against the marine environment. We use commercially available infrared pyrometers and a precision blackbody housed in a temperature-controlled enclosure. The sensors are calibrated at regular interval using a cylindro-cone target immersed in temperature-controlled water bath, which allows the calibration points to follow the ocean surface temperature. An upward-looking pyrometer measures sky radiance in order to correct for the non-unity emissivity of water, which can introduce an error of up to 0.5°C. As part of our design strategy, we have evaluated the use of an infrared transparent window to completely protect the sensor and calibration blackbody from the marine environment. A total of three units have been fabricated and deployed at sea for over 700 days since 1998. We give an overview of the design and report on the performance of the CIRIMS in comparison to the Marine-Atmosphere Emitted Radiance Interferometer (M-AERI) which is the primary in situ validation instrument for MODIS.

To deliver high quality data sets to the user community, space sensors have to be calibrated with high accuracy. Besides pre-launch and on-board calibration, there exists the possibility to inter-compare the sensor data using well-characterized ground sites. To cover different radiometric signal levels, ground sites with high and low spectral reflectance (and surface temperatures) were chosen to allow not only an absolute signal comparison, but also an estimation of the linearity of the sensor signal. This why one ground site is located at in the dark ocean (East china sea), and the other is a fresh snow site in the polar region (alternating: Arctic and Antarctic cal sites). These polar sites have the advantage to compare sensors from different sun-synchronous orbit satellites platforms on the same day, i.e. semi-simultaneous measurements can be performed. The dark ocean site will be located near Ishigaki Island (Japan) at 24°37'N and 123°27'E using optical buoy data and frequent in-situ measurements. The snow target sites are in the Antarctic and Arctic, where measurements will be carried out in the polar autumn and spring near Syowa Station (East Ongul Island, Lützow-Holm Bay, East Antarctica; 69°S and 39°35'E) and near Barrow (Alaska, USA; 71°16'N, 156°50'W). In the scope of the project the ground sites will be characterized (depending on logistical and weather conditions), to allow an estimation of the TOA signal, which will be calculated using either developed codes or generated products. After systematic (space sensor and ground-truth) data acquisition and analysis, a comparison between these space sensors will be provided to assess long-term variations and trends in the calibration. This paper describes the ongoing preparation (e.g., data selection, ground truth measurements and algorithm development) for a systematic inter-sensor comparison of the GLI and MERIS/AATSR sensors, which are onboard of ADEOS-2 and ENVISAT satellites.

Time domain reflectometry (TDR) instrumentation is widely used in hydrology and soil science for accurate and flexible soil water content measurements. The most attractive advantages concerning the considered TDR measurement system are: good precision and accuracy, high reliability of the measuring head, an unique approach of pulsing a long coaxial probe and analysing the reflected voltage signature caused by changes in impedance, capability of multiplexing several probes, possibility of remotely acceding, controlling and electronically retrieving and transmitting data through existing telecommunications. A time domain reflectometer transmits the incident signal, an ultra short rise time (200 ps), step voltage pulse, along the transmission line and records the travel time and magnitude of all reflected signals (echo) returning from the controlled system. Changes in capacitance, impedance, inductance and resistance causing electromagnetic discontinuities that reflect voltage can be located, particularly, for liquid level and soil dielectric properties monitoring purposes, discontinuities result from impedance changes produced by changes in the dielectric constant. Moreover, different systems are currently used to measure liquid levels in stocking tanks or vessels. The time domain reflectometry method used in this research has the purpose to monitor the behavior of the different liquid interfaces, detecting their levels. One of the the goals of present paper is to enhance field measurement capabilities; miniature pulsing and sampling cards have been used to create a smaller and more rugged time domain reflectometer, associated to the special steel probes working like a closed circuit radar, detecting any mismatch along the measuring lines. Measurements can be performed in a wide range of environmental conditions, independently from the nature or properties of the involved substances, giving information about their characteristics, such as volumetric content, dielectric constant, emulsions, dispersions, etc. Agreements with current TDR research data have been found. Furthermore, by characterizing several complex systems, the main objective of the present work is to develop an interpretation method based on the changes in the reflected TDR signal caused by the presence of hydrocarbons and their concentration in a soil.

The Atmospheric Infrared Sounder (AIRS) is a space based instrument developed for measurement of global atmospheric properties; primarily water vapor and temperature. AIRS is one of several instruments on board NASA's Earth Observing System Aqua spacecraft. AIRS operates in the 3.7 - 15.4 micron region and has 2378 infrared channels and 4 Vis/NIR channels. AIRS spatial resolution is 13.5 km from the orbit of 705 km and it scans ±49.5 degrees. AIRS has a set of on-board calibrators including a single infrared blackbody source, a parylene spectral calibration source, a space view and a Vis/NIR photometric calibrator. The on-board calibration subsystems are described along with a description of special test procedures for using them and results from several tests performed to date. Results are exceptional indicating that the instrument is performing better than expected.

The MODerate Resolution Imaging Spectroradiometer (MODIS) Flight Model (FM1) was launched on-board the NASA Earth Observing System (EOS)Aqua spacecraft on May 4, 2002. Following initial instrument outgas, focal plane cooling, and functional testing, Aqua MODIS opened its nadir aperture door (NAD) on June 24, 2002 and acquired the first on-orbit image. Modis has 36 spectral bands with wavelengths ranging from 0.412μ to 14.5μ. The 16 thermal emissive bands (B20-25 and 27-36) with wavelengths above 3.5μ are calibrated on-orbit by an on-board calibrator blackbody (OBC BB) on a scan by scan basis. In this paper, we provide a brief review of MODIS thermal emissive bands (TEB) calibration algorithm and present early results from Aqua MODIS on-orbit calibration and characterization, including sensor's response stability, noise assessment, and the response versus scan angle (RVS) difference between the two sides of the scan mirror. In general, the on-orbit performance of Aqua MODIS TEB has been consistent with the instrument pre-launch calibration and characterization. Compared to its Protoflight Model (PFM), or the Terra MODIS, launched on December 18, 1999, a number of improvements have been achieved. During instrument on-orbit operation, the BB can be operated from 270 - 315 K (during scheduled warm-up/cool-down cycle). When the BB temperature is above certain limits, three thermal emissive bands (33, 35, and 36) saturate when directly viewing the calibration source. We have developed an algorithm of using the Look-Up Table (LUT) gain coefficients for these three bands to keep the Earth view data calibrated under this situation. An illustration of on-orbit performance of this approach is provided.

The paper describes the test results of the hardware model of a smart pushbroom imaging system. The imaging system can be used on satellites with moderately attitude stability due to application of the image correction on base of the real-time image motion record by an optoelectronic image processor and auxiliary sensors in the focal plane. The tested model includes the breadboard model of a smart pushbroom camera with auxiliary sensors, the optoelectronic processor model and the image correction software. The tests have been performed on a laboratory satellite motion simulator based on a 5 DOF industrial robot. Numerical values of the image motion record accuracy and the image correction efficiency are given as well as a detailed test description.

The CALIPSO LIDAR is a two-channel visible/infrared, polarization sensitive space based instrument. The mission specifies a lightweight, thermally stable platform for the lasers, 1-m telescope, and LIDAR instrumentation. Stability requirements include ±26 μrad boresight stability between the telescope and the laser as well as ±10 μm optical bench thickness stability and ±70 μm stability of components on the optical bench. The environment for these performance criteria is a 0 C to 50 C space environment. In order to demonstrate performance, a laser tracker, a laser comparator, and an electronic autocollimator were used in conjunction with an environmental chamber to measure the stability of the structure over the operating temperature range.

As Doppler lidars designed for environmental remote sensing move from ground-based platforms to airborne and space-based platforms, issues related to processing surface and near-surface returns are of increasing interest. In the case of Doppler wind lidars, the surface returns can be useful in calibrating the velocity estimates along the associated lines-of-sight, assuming the surface is not moving relative the Earth's frame of reference. This assumption may not hold for water surfaces and in that case, the Doppler signal might be useful in estimating surface currents (rivers and oceans). Whether the water returns are used for calibrating wind lidars or making water current measurements, the confounders of accurate observations include waves and the independent motions of overlying aerosols in the layer adjacent to the surface (LAS). As part of a program to develop calibration/validation techniques for space-based Doppler wind lidars, a series of laboratory and airborne experiments are being executed. At NASA/MSFC a water slide has been constructed and used with a 2μm coherent lidar to study the signal from water surfaces having varying velocities, roughnesses and turbidities. The angle of the water slide to the lidar beam can also be varied to test the theoretical function of signal return vs. angle of incidence. Results of those experiments have provided input to the design and execution of a set of airborne 2μm coherent lidar experiments conducted in February and March 2002 out of Monterey, CA. The airborne system (funded by the US Navy and the Integrated Program Office of the NPOESS) collected data to be used to develop signal processing algorithms that can discriminate between the water surface motions and the velocity of the wind blown aerosols that are combined in the signal from just one range gate. This paper will report on both sets of experiments.

The SeaWiFS Project uses daily on-orbit detector and gain calibrations to address issues which arise from the bilinear gain in the SeaWiFS radiometric response function. The bilinear gains provide high sensitivity over the ocean while preventing saturation over clouds or land. The bilinear gains are implemented by averaging the output from three high-sensitivity ocean detectors and one low-sensitivity cloud detector for each band. The calibration issues are: 1) the applicability of time corrections computed from lunar data obtained at one set of instrument gains to ocean data obtained at a different set of gains; and 2) the applicability of time corrections computed from data obtained with all four detectors in each band to the cloud detector alone. The Project uses the gain calibration to monitor the SeaWiFS gain ratios over time. The gain ratios for each detector are computed from measurements at each gain of a constant voltage injected into the post-detector electronics. The gain ratios are stable to within 0.1% over the course of the mission. The Project uses the detector calibrations to compare the response of individual detectors within each band to the response of the four detectors in that band. The detector response is monitored during a modified solar calibration where measurements are obtained from each detector. The departure of the cloud detectors from the four detectors is less than 0.5% for all eight bands. These analyses show that, for SeaWiFS, the time corrections derived from lunar calibrations are applicable to both ocean and land data.

The radiometric calibration of the two optical sensors on the Earth Observing One satellite has been studied as a function of time since launch. The calibration has been determined by ground reference calibrations at well-characterized field sites, such as White Sands Missile Range and dry playas, and by reference to other sensors such as the Enhanced Thematic Mapper Plus (ETM+) on Landsat 7. The ground reference calibrations of the Advanced Land Imager (ALI) give results consistent with the on-board solar calibrator and show a significant shift since preflight calibration in the short wavelength bands. Similarly, the ground reference calibrations of Hyperion show a change since preflight calibration, however, for Hyperion the largest changes are in the short wave infrared region of the spectrum. Cross calibration of ALI with ETM+ is consistent with the ground reference calibrations in the visible and near infrared. Results showing the changes in radiometric calibration are presented.

The Advanced Land Imager (ALI) is the primary instrument on the Earth Observing-1 spacecraft (EO-1) and was developed under NASA's New Millennium Program (NMP). The NMP mission objective is to flight-validate advanced technologies that will enable dramatic improvements in performance, cost, mass, and schedule for future, Landsat-like, Earth Science Enterprise instruments. ALI contains a number of innovative features designed to achieve this objective. These include the basic instrument architecture, which employs a push-broom data collection mode, a wide field-of-view optical design, compact multi-spectral detector arrays, non-cryogenic HgCdTe for the short wave infrared bands, silicon carbide optics, and a multi-level solar calibration technique. The sensor includes detector arrays that operate in ten bands, one panchromatic, six VNIR and three SWIR, spanning the range from 0.433 to 2.35 μm. Launched on November 21, 2000, ALI instrument performance was monitored during its first year on orbit using data collected during solar, lunar, stellar, and earth observations. This paper will provide an overview of EO-1 mission activities during this period. Additionally, the on-orbit spatial and radiometric performance of the instrument will be compared to pre-flight measurements and the temporal stability of ALI will be presented.

Near nadir observations in the 11μm and 12 μm bands of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the TERRA spacecraft and the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA-16 spacecraft are collected at their orbit intersections, where both MODIS and AVHRR view the Earth and its atmosphere at the same location within 30 seconds in the Arctic region. Sample data with 1 km resolution from spatially uniform areas are taken for direct inter-comparison of the scene radiance and brightness temperatures at around 270 K. Then a pixel-by-pixel match between the MODIS and AVHRR observations is performed to evaluate their correlation at different scene temperatures. The results show that MODIS and AVHRR observations agree well (difference less than 0.3 K) for both the 11μm and 12 μm bands, although their band correlation exhibits a slightly non-linear trend for scene temperatures greater than 285 K. The performance of MODIS is considered a good predictor of the performance of the National Polar-orbiting Operational Environmental Satellite System (NPOESS)/Visible Infrared Imager/Radiometer Suite (VIIRS), the future replacement of AVHRR. The direct comparison of MODIS and AVHRR observations is therefore considered a risk reduction study for VIIRS.

In-flight measurements of spatial resolution were conducted as part of the NASA Scientific Data Purchase Verification and Validation process. Characterization included remote sensing image products with ground sample distance of 1 meter or less, such as those acquired with the panchromatic imager onboard the IKONOS satellite and the airborne ADAR System 5500 multispectral instrument. Final image products were used to evaluate the effects of both the image acquisition system and image post-processing. Spatial resolution was characterized by full width at half maximum of an edge-response-derived line spread function. The edge responses were analyzed using the tilted-edge technique that overcomes the spatial sampling limitations of the digital imaging systems. As an enhancement to existing algorithms, the slope of the edge response and the orientation of the edge target were determined by a single computational process. Adjacent black and white square panels, either painted on a flat surface or deployed as tarps, formed the ground-based edge targets used in the tests. Orientation of the deployable tarps was optimized beforehand, based on simulations of the imaging system. The effects of such factors as acquisition geometry, temporal variability, Modulation Transfer Function compensation, and ground sample distance on spatial resolution were investigated.

The success of the Modular Optoelectronic Scanner MOS on the Indian Remote Sensing Satellite IRS-P3 during the 6 years mission time has been based on its sophisticated in-orbit calibration concept to a large extent. When the internal lamp and the sun calibration failed in September 2000 we tested the possibility of ground target based (or vicarious) calibration of the MOS instruments to continue the high data quality. This is essential for future watching of global changes of the ocean coastal zones (phytoplancton, sediments, pollution, etc.) using spectral measurements of the VIS/NIR MOS spectral channels. The investigations have shown the suitability of a part of the Great Eastern Erg in the Sahara desert for this purpose. The satellite crosses this very homogeneous area every 24 days. Because of the good cloudfree conditions we can use 6 - 8 overflys a year for calibration. The seasonal variability of the surface reflectance is very small so that we obtain relative calibration data of sufficient accuracy even without ground truth measurements for most of the channels. The trend of this "vicarious" calibration corresponds very well with the previous trend of the failed lamp and sun calibration. Dfferences between the three methods will be discussed. In the paper we will also present the results of a comparison between SeaWiFS and MOS data of comparable spectral channels from the Great Eastern Erg area. They confirm the suitability of this area for calibration purposes too.

The MODIS Protoflight Model (PFM), on-board the NASA EOS Terra spacecraft, has been in operation for more than two years. Its 20 reflective solar bands (RSB) from 0.412μ to 2.13μ are calibrated on-orbit by a solar diffuser (SD) with its degradation tracked by a solar diffuser stability monitor (SDSM). The results derived from the SD/SDSM calibration data have shown that SD degradation is wavelength dependent. After nearly 2.5 years, the SD has degraded about 7.0% at 0.412μ, 4.0% at 0.466μ, 2.1% at 0.530μ, and the degradation is smaller at other longer wavelengths. The MODIS optical system includes a rotating scan mirror and other fixed aft optics. Overall system response in the visible spectral range has also shown wavelength dependent degradation over time. This degradation varies with the angle of incidence (AOI) to the scan mirror and the degradation rate is different between two sides of the scan mirror. During the first 20 months of instrument on-orbit operation, the system degradation (mirror side 1) at SD calibration AOI (50.2β) is about 11% at 0.412μ (MODIS Band 8), 6.5% at 0.443μ (Band 9), 5.0% at 0.469μ (Band 3), and 4.0% at 0.488μ (Band 10). Again the degradation is smaller for other bands with longer wavelengths. At other smaller AOIs, our results show that the degradation rate is higher. Since Oct./Nov. 2001, the system response degradation has essentially stopped. In this paper, we present MODIS RSB degradation analyses and the associated trending results including degradation at different AOIs to the scan mirror. We also address their impact on and application to the RSB on-orbit calibration.

MODerate Resolution Imaging Spectroradiometer (MODIS) Proto-Flight Model (PFM) on-orbit spatial characterization includes Band to Band registration (BBR) and the Modulation Transfer Function (MTF) of 36 bands located on four focal plane assemblies (VIS, NIR, SMWIR, and LWIR). These parameters were also measured prelaunch using ground calibration equipment. The on-board Spectro-Radiometric Calibration Assembly (SRCA) was used both prelaunch and on-orbit to monitor the BBR and MTF changes. In this paper, we report the MODIS on-orbit spatial characterization results derived from the SRCA and their comparisons with pre-launch values. Results from SRCA measurements show that the BBR stabilized on-orbit after about 100 days. Currently, the averaged FPA positions in the along-scan direction, relative to band 1 (NIR), have changed from prelaunch values by -2m for VIS, 17m for SMWIR, and -20m for LWIR; along-track changes are 43m for VIS, -36m for SMWIR, and -22m for LWIR. The MTF in the along-scan direction shows a small improvement over prelaunch. Also in this paper, we discuss a methodology that uses the sensor's on-orbit views of the Moon for the BBR characterization. Comparison of the results from the Moon and those from the SRCA provides an evaluation of the methodology and its applicability for other remote sensing instruments without an on-board spatial characterization calibrator.

Clouds and the Earth's Radiant Energy System (CERES) is an investigation into the role of clouds and radiation in the Earth's climate system. Two CERES scanning thermistor bolometer instruments are aboard the Earth Observing System (EOS) Terra satellite that was launched 18 December 1999. Each CERES instrument has three sensors that measure in distinct broadband radiometric regions: the shortwave channel (0.3 - 5.0 μm), total channel (0.3 - greater than 100 μm), and window channel (8 - 12 μm). Two analyses have been implemented to aid in monitoring the stability of the measurements of the instruments. One analysis is a three-channel inter-comparison of the radiometric measurements for each instrument. This procedure derives an estimate of the shortwave portion of the total channel sensor radiance measurement. The second analysis is a direct comparison of temporally synchronized nadir measurements for each sensor of the two instruments. Use of these analyses indicates that the shortwave region of the measurements is drifting over mission lifetime for both instruments. A discussion of correcting the shortwave drift using ground software is included.

Between November 1984 and July 2002, the Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) nonscanning, active cavity radiometers (ACR) were used to measure incoming total solar irradiance, earth-reflected solar irradiance, and earth-emitted outgoing longwave radiation (OLR) irradiance. The ERBE shortwave wide field-of view (SWFOV) and toal wide field-of-view (TWFOV) ACR's measured irradiances from the entire earth disc in the shortwave (0.2-5.0 μm) and total (0.2-100 μm) broadband spectral regions. On-orbit, the ACR's observations of the incoming total solar irradiance, and of reference irradiance from on-board tungsten lamp and blackbodies were used to determine drifts and shifts in the ACR responses/gains. In the cases of the SWFOV ACR, its response/gain changed as much as 8.8% while the TWFOV response was stable at levels better than 0.1%. The precise measurements of gain and offset variations have permitted the generations of ERBE level 1 data products [earth-reflected solar (≈240 Wm^-2)and earth-emitted (≈100 Wm^-2) irradiances] at the precision levels better than 0.3 Wm^-2. In this paper, the ACR radiometric on-orbit calibration approaches and systems are outlined.

NASA developed the Earth Observing System (EOS) during the 1990's. At the Land Processes Distributed Active Archive Center (LP DAAC), located at the USGS EROS Data Center, the EOS Data and Information System (EOSDIS) is required to support heritage missions as well as Landsat 7, Terra, and Aqua. The original system concept of the early 1990's changed as each community had its say -- first the managers, then engineers, scientists, developers, operators, and then finally the general public. The systems at the LP DAAC -- particularly the largest single system, the EOSDIS Core System (ECS) -- are changing as experience accumulates, technology changes, and each user group gains influence. The LP DAAC has adapted as contingencies were planned for, requirements and therefore plans were modified, and expectations changed faster than requirements could hope to be satisfied. Although not responsible for Quality Assurance of the science data, the LP DAAC works to ensure the data are accessible and useable by influencing systems, capabilities, and data formats where possible, and providing tools and user support as necessary. While supporting multiple missions and instruments, the LP DAAC also works with and learns from multiple management and oversight groups as they review mission requirements, system capabilities, and the overall operation of the LP DAAC. Stakeholders, including the Land Science community, are consulted regularly to ensure that the LP DAAC remains cognizant and responsive to the evolving needs of the user community. Today, the systems do not look or function as originally planned, but they do work, and they allow customers to search and order of an impressive amount of diverse data.

As the EOSDIS archives grow, it could easily become more difficult for users to find and retrieve the data they need and to quickly get that data into a form they can use. NASA has been developing capabilities to address this concern over the past year and recently deployed an initial set of capabilities to its major Distributed Active Archive Centers (DAACs). The solution, called Data Pools, makes a significant portion of the data in the EOSDIS archives available on-line for immediate access, and provides several innovative data navigation, tailoring and rapid access services to help users quickly find just the data they need, get it into a form they can use, and then quickly retrieve the data. This paper describes the Data Pool architecture, and its approach to addressing data location, tailoring and retrieval difficulties that could have eventually plagued EOSDIS users. The paper also discusses how the Data Pools architecture could be expanded to provide a cost-effective evolutionary architecture for EOSDIS.

The U.S. Geological Survey EROS Data Center archives, processes, and disseminates Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data products. The ASTER instrument is one of five sensors onboard the Earth Observing System's Terra satellite launched December 18, 1999. ASTER collects broad spectral coverage with high spatial resolution at near infrared, shortwave infrared, and thermal infrared wavelengths with ground resolutions of 15, 30, and 90 meters, respectively. The ASTER data are used in many ways to understand local and regional earth-surface processes. Applications include land-surface climatology, volcanology, hazards monitoring, geology, agronomy, land cover change, and hydrology. The ASTER data are available for purchase from the ASTER Ground Data System in Japan and from the Land Processes Distributed Active Archive Center in the United States, which receives level 1A and level 1B data from Japan on a routine basis. These products are archived and made available to the public within 48 hours of receipt. The level 1A and level 1B data are used to generate higher level products that include routine and on-demand decorrelation stretch, brightness temperature at the sensor, emissivity, surface reflectance, surface kinetic temperature, surface radiance, polar surface and cloud classification, and digital elevation models. This paper describes the processes and procedures used to archive, process, and disseminate standard and on-demand higher level ASTER products at the Land Processes Distributed Active Archive Center.

In this paper, a new image reconstruction scheme is devised for estimating a high resolution temperature map of the top of the earth's atmosphere using the GOES-8 (Geostationary Operational Environmental Satellite) imager infrared channels. By simultaneously interpolating the image while estimating temperature, the proposed algorithm achieves a more accurate estimate of the sub-pixel temperatures than could be obtained by performing these operations independently of one another. The proposed algorithm differs from other Bayesian-based image interpolation schemes in that it estimates brightness temperature as opposed to image intensity and incorporates a detailed optical model of the GOES multi-channel imaging system. In order to test the effectiveness of the proposed technique, high resolution estimates of cloud top temperatures using a single GOES infrared channel are compared to temperature estimates obtained from the AVHRR (Advanced Very-High Resolution Radiometer). This test is achieved by examining sets of infrared data taken simultaneously by the GOES and AVHRR systems over the same geographic area. The AVHRR system collects long-wave infrared data with a spatial resolution of 1 kilometer, which is higher than the 4-kilometer spatial resolution the GOES system achieves. In some cases the estimated temperature differences between these systems are as high as 10 degrees Kelvin. It is shown in this paper that the proposed algorithm consistently improves the consistency between the cloud top temperatures estimated with the GOES and AVHRR systems by allowing the GOES system to achieve substantially higher spatial resolution.

We describe a system for interactive training of models for semantic labeling of land cover. The models are build based on three levels of features: 1) pixel level, 2) region level, and 3) scene level features. We developed a Bayesian algorithm and a decision tree algorithm for interactive training. The Bayesian algorithm enables training based on pixel features. The scene level summaries of pixel features are used for fast retrieval of scenes with high/low content of features and scenes with low confidence of classification. The decision tree algorithm is based on region level features that are extracted based on 1) spectral and textural characteristics of the image, 2) shape descriptors of regions that are created through segmentation process, and 3) auxiliary information such as elevation data. The initial model can be created based on a database of ground truth and than be refined based on the feedback supplied by a data analyst who interactively trains the model using the system output and/or additional scenes. The combination of supervised and unsupervised methods provides a more complete exploration of model space. A user may detect the inadequacy of the model space and add additional features to the model. The graphical tools for the exploration of decision trees allow insight into the interaction of features used in the construction of models. The preliminary experiments show that accurate models can be build in a short time for a variety of land covers. The scalable classification techniques allow for fast searches for a specific label over a large area.

This paper compares different filters used to register images taken from different satellites to subpixel precision. The registration algorithm is one proposed by Thevenaz et al which uses a modified Levenberg-Marquardt process to find the rigid transform that best maps one image into another. Our findings are that while applied to single-sensor synthetic data, centered spline filters and the low pass band of Simoncelli steerable pyramid are equally sensitive to initial guess while the bandpass sub-band of the Simoncelli filters exhibits larger senstivity. For multisensor and noisy data, however, the bandpass filters produce the most consistent results.

The accuracy of the Moderate Resolution Imaging Spectroradiometer (MODIS) end data products, such as the Vegetation Indices (VIs), are affected by MODIS's Spatial Response (SR). An error analysis is presented for the VI (MOD-13) product using Point Spread Response (PSR) data and improvement using a correction filter is demonstrated. The PSR data is a set of laboratory measurements that include electronic/optical cross-talk (pre-August 1998). The ensquared energy concept is applied to the PSR data to determine upper limits for the Far Field Response (FFR)(unwanted noise) that may be present in the MODIS data. The error is presented using spectral variation, Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) which demonstrate that the science products are dependent on the sensor's SR. A correction filter for the MODIS SR shows a qualitative and quantitative improvement using a scene Railroad Valley scene, June 14^th 2001 in which Landsat 7 ETM+ is used as the reference.

SAGE III is a NASA EOS instrument designed to provide long term measurements of ozone, aerosol, water vapor, and other gases in the atmosphere. The instrument was launched on a Russian Spacecraft Meteor 3M on December 10, 2001. This paper will provide a brief discussion of the SAGE III data that will be made available to the science community to perform study on problem related to global climate change issues. The SAGE III measurement strategy, data retreival technique, and the expected quality of the data products will be discussed. Preliminary data obtained from the instrument will be presented.