This PDF file contains the front matter associated with SPIE Proceedings Volume 7827, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

We present a satellite remote sensing technique to retrieve the cloud optical thickness (COT) which is based on visible and shortwave infrared imagery from MSG-SEVIRI. The semi-analytical cloud retrieval algorithm (SACURA) is implemented on a monthly dataset of SEVIRI level 1.5 images. The background surface albedo (A) plays an important role for thin clouds. Thus, A is calculated by the minimum composite approach of reflectance in the visible channel, at pixel level, during the month. Cloud ice and cloud water discrimination scheme is made on the basis of ratio of reflectance in channel 1.6 μm to 0.6 μ. Reflectance of semi-infinite (R 0 ∞) cloud is a function of cosines of solar azimuth angle (v_o), satellite azimuth angle (v) and relative azimuth angle (Ψ). Thus, reflectance values, R 0 ∞, R 0 ∞, are interpolated from a look up table of reflectance, calculated from radiative transfer model, to corresponding sun-satellite angular values. Hence, total scaled cloud optical thickness is calculated as summation of scaled cloud optical thickness of water and scaled cloud optical thickness of ice. The result is compared with that of Cloudsat and it shows good agreement.

The SEVIRI imager on current generation of geostationary Meteosat has 12 channels with a horizontal resolution of 3 km at the sub-satellite point. EUMETSAT cloud processing includes the cloud detection (cloud/no cloud decision) on pixel basis with an image update cycle of 15 minutes. The cloud mask product is used during the period 2007-2010 to assess the quality of a mountain site in the Moroccan Anti Atlas for astronomical observing. The performance of the satellite data extraction algorithm is tested against ground based measurements performed at a well established reference site: the Observatory Roque de los Muchachos (ORM) on the Island of La Palma.

A solution based on a Kalman filter to trace the evolution of the atmospheric boundary layer (ABL) sensed by an elastic backscatter lidar is presented. An erf-like profile is used to model the mixing layer top and the entrainment zone thickness. The extended Kalman filter (EKF) enables to retrieve and track the ABL parameters based on simplified statistics of the ABL dynamics and of the observation noise present in the lidar signal. This adaptive feature permits to analyze atmospheric scenes with low signal-to-noise ratios without need to resort to long time averages or rangesmoothing techniques, as well as to pave the way for an automated detection method. First EKF results based on synthetic lidar profiles are presented and compared with a typical least-squares inversion for different SNR scenarios.

In-flight icing occurs when aircraft impact supercooled liquid drops. The supercooled liquid freezes on contact and the accreted ice changes a plane's aerodynamic characteristics, which can lead to dangerous loss of control. NASA's Icing Remote Sensing System consists of a multi-channel radiometer, a laser ceilometer and a vertically-pointing Kaband radar, whos fields are merged with internal software logic to arrive at a hazard classification for in-flight icing. The radiometer is used to derive atmospheric temperature soundings and integrated liquid water and the ceilometer and radar are used to define cloud boundaries. The integrated liquid is then distributed within the determined cloud boundaries and layers to arrive at liquid water content profiles, which if present below freezing are categorized as icing hazards. This work outlines how the derived liquid water content and measured Ka-band reflectivity factor profiles can be used to derive a vertical profile of radar-estimated particle size. This is only possible because NASA's system arrives at independent and non-correlated measures of liquid water and reflectivity factor for a given range volume. The size of the drops significantly effect the drop collection efficiency and the location that icing accretion occurs on the craft's superstructure and thus how a vehicle's performance is altered. Large drops, generally defined as over 50 μm in diameter, tend to accrete behind the normal ice protected areas of the leading edge of the wing and other control surfaces. The NASA Icing Remote Sensing System was operated near Montreal, Canada for the Alliance Icing Research Study II in 2003 and near Cleveland, Ohio from 2006 onward. In this study, we present case studies to show how NASA's Icing Remote Sensing System can detect and differentiate between no icing, small drop and large drop in-flight icing hazards to aircraft. This new product provides crucial realtime hazard detection capabilities which improve avaiation safety in the near-airport environment with cost-effective, existing instrumentation technologies.

The assessment of airport air quality requires not only the knowledge of the emissions and the temporal and spatial distribution of meteorological parameters like wind direction and wind speed but also of the mixing layer height, because this variable controls the vertical space for rapid mixing of near-surface pollutants. It was demonstrated that the lowest stable layer or temperature inversion limits the vertical exchange of primary pollutants emitted at or near the surface and thus controls the near-surface pollutant concentrations. Remote sensing is a suitable tool to determine mixing layer height continuously as was demonstrated in urban and sub-urban areas (Hannover, Munich, Budapest, Augsburg) as well as at airports (Zurich, Paris CDG, Mexico City International Airport, Athens International Airport). The Vaisala ceilometer LD40 was used which is an eye-safe commercial lidar and designed originally to detect cloud base heights and vertical visibility for aviation safety purposes. These measurements of the vertical aerosol distribution are routinely retrieved for mixing layer height estimation by using software which was improved continuously and compared with radiosonde data. Further, mixing layer height was determined by remote sensing with a combination of a Doppler- SODAR (Sound Detection and Ranging), a RASS (Radio Acustic Sounding System) and in-situ measurements. Vertical wind, temperature and turbulence parameter profiles up to 1500 m maximum were measured by this method too. Some results of interpretation of measured data at Athens International Airport will be discussed as the influence of mixing layer height upon airport air quality and estimation of the airport emission source strengths.

Since 2006 different remote monitoring methods for mixing layer height have been operated in Augsburg. One method is based on eye-safe commercial mini-lidar systems (ceilometers). The optical backscatter intensities recorded with these ceilometers provide information about the range-dependent aerosol concentration; gradient minima within this profile mark the tops of mixed layers. A special software for these ceilometers provides routine retrievals of lower atmosphere layering. A second method, based on SODAR (Sound Detection and Ranging) observations, detects the height of a turbulent layer characterized by high acoustic backscatter intensities due to thermal fluctuations and a high variance of the vertical velocity component. This information is extended by measurements with a RASS (Radio-Acoustic Sounding System) which provide the vertical temperature profile from the detection of acoustic signal propagation and thus temperature inversions which mark atmospheric layers. These SODAR and RASS data are the input to a software-based determination of mixing layer heights developed with MATLAB. A comparison of results of the three remote sensing methods during simultaneous measurements was performed. The information content of the ceilometer data is assessed by comparing it to the results from the other two instruments and near-by radiosonde data.

The objective of the OCO (Orbiting Carbon Observatory) mission was to make the first space-based measurements of atmospheric carbon dioxide with the accuracy needed to quantify sources and sinks of this important greenhouse gas. Unfortunately, the observatory was lost as a result of a launch vehicle failure on 24 February 2009. The JPS (Jet Propulsion Laboratory) was directed to assess the options for the re-flight of the OCO instrument and recovery of the carbon-related measurement, and to understand and quantitatively asses the cost, schedule, and technical and programmatic risks of the indentified options. The two most likely solutions were (1) a shared platform with the TIRS (Thermal Infrared Sensor) instrument and (2) a dedicated OSC(Orbital Sciences Corporation) LEOStar-2 spacecraft bus similar to the utilized for the original OCO mission. A joint OCO-TIRS mission study was commissioned and two specific options were examined. However, each presented technical challenges that would drive cost. It was determined that the best option was to rebuilt the OCO observatory to the extent possible including another LEOStar-2 spacecraft bus. This lower risk approach leverages the original OCO design and provides the shortest path to launch, which is targeted for no later than February 2013 timeframe.

The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. Early in the mission, the AIRS instrument demonstrated its value to the weather forecasting community with better than 6 hours of improvement on the 5 day forecast. Now with over eight years of consistent and stable data from AIRS, scientists are able to examine processes governing weather and climate and look at seasonal and interannual trends from the AIRS data with high statistical confidence. Naturally, long-term climate trends require a longer data set, but indications are that the Aqua spacecraft and the AIRS instrument should last beyond 2018. This paper briefly describes the AIRS data products and presents some of the most significant findings involving the use of AIRS data in the areas of weather forecast improvement, climate processes and model validation, cloud and polar processes, and atmospheric composition (chemistry and dust).

It has been shown by Hadjimitsis et al. (2009) that the use of suitable non-variant targets in conjunction with the application of the empirical line method can remove atmospheric effects from satellite images effectively. The method is based on the selection of a number of suitable generic non-variant targets, on the basis that they are large, distinctive in shape, and occur in many geographical areas. The need to further test such method by suggesting more suitable nonvariant targets is one of the main aims of this study. Indeed, six targets have been already identified in the Lemesos District area in Cyprus, near the harbour and tested. In-situ spectro-radiometric measurements using the SVC HR-1024 field spectro-radiometer have been made on November 2009 and from February 2010 to April 2010. Some of the in-situ measurements were coincided with the Landsat TM/ETM+ overpass and the removal of atmospheric effects was very effective. The above targets have been scanned using a 3D terrestrial laser scanner (Leica ScanStation C10) so as to investigate the non-variability and uniformity of the proposed targets (through the laser scanner intensity values).

Atmospheric correction is still considered as the most important part of pre-processing of satellite remotely sensed images. The accuracy assessment of the existing atmospheric correction must be monitored on a systematic basis since the user must be aware about the effectiveness of each algorithm intended for specific application. Indeed this study integrates the following measurements coincided with the satellite overpass (ASTER and Landsat TM/ETM+) in order to assess the accuracy of the most widely used atmospheric correction algorithms (such as darkest pixel, atmospheric modelling, ATCOR, 6S code etc.): spectroradiometric measurements of suitable calibration targets using GER1500 or SVC HR-1024 field spectro-radiometers, MICROTOPS hand held sun-photometers, LIDAR backscattering system, CIMEL sun photometer (Cyprus University of Technology recently joined with AERONET).

This paper designs a style of particle counter which may measure the aerodynamic size and the scattering intensity of two scattering angles of the aerosol particles. The scattering intensity can also be calculated from the size and the refractive index according to the Mie theory. When the aerodynamic size is equal to the optics size approximatively, we can inverse the refractive index of individual aerosol particles by combining the relative results of the measurements.

According to the "contrast reduction" principle the aerosol optical thickness (AOT) can be retrieved and mapped over heterogeneous (such as urban) areas using a set of two satellite images of high spatial resolution: (i) one "reference image" with minimum aerosol content involving negligible AOT, and (ii) one "polluted image" with AOT to be assessed. AOT values retrieved in this way are thus relative to the reference image, and could be miscalculated when other than atmospheric changes have taken place in the time between the acquisitions of the two images. Previously developed DTA and SMA image processing codes are subject to this potential source of AOT miscalculation because the contrast reduction is applied to single spectral bands. The new CHRISTINE code takes into consideration contrast reduction in more than one spectral band and uses the Angstrom's power law to isolate atmospheric effects attributable to aerosols. Preliminary testing of the new code over the Athens urban area against results obtained using the previous codes showed a considerable improvement in terms of the area over which AOT can be retrieved with high confidence. CHRISTINE has also a complementary feature of providing information on the aerosol size distribution emerging from Angstrom coefficient approximation.

In site selection processes, one key parameter is the extinction coefficient. This parameter depends on aerosol load, water vapor content and atmospheric gazes. Actually a lot of satellite instruments give the aerosol optical thickness over the earth with good spatial and temporal resolutions. The determination of the extinction coefficient at elevated altitudes from photometric surface measurements at lower altitudes is very important in the field of site testing. In the first part of this paper we make a comparison between the extinction coefficient measured at ground level and the aerosol optical thickness measured from space at La Palma observatory in order to study the reliability of the aerosol satellite instruments. We used the most popular ones: MODIS Terra and Aqua, MISR and Envisat Meris. In the second part of the paper, we use three AERONET (Aerosol Robotic Network) stations close to one another at the Canary Islands; Izana (longitude=16.5°W, latitude=28.3° N, altitude= 2367m), La laguna (longitude=16.32°W, latitude=28.50°N, altitude=568 m) and Santa-Cruz Tenerife (longitude=16.25°W, latitude=28.5°N, altitude=52 m). The aerosol optical thicknesses relative to these stations were studied in order to develop some empirical relationships that help determine photometric quality of an astronomical observatory from satellite measurements (even with very low resolution) or from in-situ measurements of very low elevated nearby places. LIDAR (Ligth Detection and Ranging) data of Santa-Cruz Tenerife provided by the MPLNET (Micro-Pulse Lidar Network) network were also used.

To study the gaseous pollutants and those compounds important for secondary aerosol formation like SO2, NO, and NO2 a DOAS is operated since beginning of April 2009 in Beijing. Information about different emission sources are provided by this one instrument i.e. by path-integrated air pollution information in different directions. The DOAS from OPSIS GmbH contains an analysator (AR 500) and an emitter/receiver unit (ER 130) pointing to three retroreflectors. One retroreflector was installed at a lamp mast on the other side of the motorway (568 m path length) so that the path was about 10 m above motorway level and perpendicular across the motorway. Another retroreflector was set up for a path (126 m path length) in nearly the same direction across a normal street with shops and restaurants and the third retroreflector was used to operate a path (266 m path length) perpendicular to and away from the motorway. The emitter/receiver unit was in a distance of about 20 m to an air pollution monitoring station at the roof of that building. Furthermore, a ceilometer was used to analyse the actual development of the mixing layer height and boundary layers as well as the vertical distribution of aerosols and particles. These data are used to show the meteorological influences and the role of emissions within the context of the air quality in Beijing relevant for measures to reduce the air pollution.

Remote sensing by infrared spectroscopy allows identification and quantification of atmospheric gases as well as airborne pollutants. Infrared hyperspectral sensors deliver high spectral and spatial resolution images of a scene. By analyzing the spectra, gas emissions, for example from industrial plants, chemical accidents, or ships can be identified and quantified from long distances. The image of the cloud can be used to pinpoint the source of the gas as well as to assess the dimension and the dispersion of the cloud. A hyperspectral sensor based on the method of Fourier-transform spectroscopy has been developed. A cube corner Michelson interferometer with large optical apertures has been designed specifically for the task. In addition, the system encompasses a cooled infrared focal plane array detector, a calibration source, and a video camera. The system is compact and field portable. Field measurements were conducted on ship exhausts. Gas clouds were successfully visualized and identified.

Airborne infrared limb-viewing sensors may be used as surveillance devices in order to detect dim military targets. These systems' performances are limited by the inhomogeneous background in the sensor field of view which impacts strongly on target detection probability. Consequently, the knowledge of the radiance small-scale angular fluctuations and their statistical properties is required to assess the sensors' detection capacity. In the stratosphere and in clear-sky conditions, the structured background is mainly due to inertia-gravity-wave and turbulence-induced temperature and density spatial fluctuations. Moreover, in the particular case of water vapor absorption bands, the mass fraction fluctuations play a non negligible role on the radiative field. Thereby, considering as a first approximation the temperature field and the water vapor field as stationary stochastic processes, the radiance autocorrelation function (ACF) can be expressed as a function of the temperature ACF and the water vapor mass fraction ACF. This paper presents the model developed to compute the two-dimensional radiance angular ACF. This model requires the absorption coefficients and their temperature derivatives, which were calculated by a line-by-line code dedicated to water vapor absorption bands. An analytical model was also developed for a simple homogeneous case, in order to validate the average values and the radiance fluctuation variance. The numerical model variance and variance distribution are also compared to SAMM2 outputs, the AFRL radiance structure computation code. The influence of water vapor fluctuations on radiance fluctuations is also discussed.

We have combined ground-based and space-based measurements and modeling of the mesosphere-lower thermosphere to study the zonal and seasonal variability of the semidiurnal thermal tide. This study uses resonance lidar soundings of temperatures from 80-100 km at Arecibo, PR (18°N, 67°W) and Maui, HI (20°N, 156°W) and observations from the SABER instrument aboard TIMED. Findings include general dominance of migrating tides through most of the year, excepting January, when the lidar-measured Maui phase front is much shallower than that observed by SABER or Arecibo lidar. At both sites the GSWM-02-predicted phase is later at lower altitudes than observations. GSWM-02 has difficulty reproducing the observed phase structure for July and August as well, months when observed phases are in fairly good agreement. Observations also show that the semidiurnal thermal tide phase has a 6-h (or 180-degree) shift between winter and the other seasons. The winter phase structure appears to set up in late November for Arecibo, and the structure returns to the non-winter phase between late February and early March. SABER observations show that the longitudinal phase variation is large in January and small for other seasons. A modal decomposition shows that the (2, 3) Hough mode is large most of the year but small in January, setting up an asymmetric tidal structure in the solstice periods. Solstice ground-observed amplitudes are large, while from space the winter amplitudes are small, indicating the importance of local effects.

Clouds and the Earth's Radiant Energy System (CERES) instruments are scanning radiometers on board the Terra and Aqua satellites since March of 2000 and June of 2002, respectively; hence, a continuous Earth's radiation budget dataset is more than a decade long. Since there are four CERES scanners in operation, it is important that their measurements are consistent. A focus of this paper is on putting Terra CERES on the same radiometric scale. The paper contains description of radiation budget experiments that are used in the process and a complete set of results. It is shown that one-time gain adjustments are sufficient in putting FM2 on the same radiometric scale as FM1, and they are to be used in processing the Edition 3 of CERES Erbe-like data products.

An alternative algorithm is being developed to retrieve ozone vertical distribution information from the OMPS/LP sensor which will be manifested on the upcoming NPOESS Preparatory Project (NPP) platform in late 2011. In contrast to most limb sensors retrieval methods, the proposed algorithm will forgo the spherical symmetry assumption for the atmospheric structure, and will attempt to simultaneously retrieve the ozone distribution in both the vertical and the along-track directions. The paper describes the two-dimensional forward model as well as the methods which have been developed to simultaneously retrieve a whole orbit of data. Sample retrieval results are shown to illustrate the technique.

An approach for the obtaining column intensive aerosol properties, namely the single scattering albedo (SSA) and asymmetry parameter (ASP), from the Multi-Filter Rotating Shadowband Radiometer (MFRSR) spectral observations under partly cloudy conditions is described. The approach involves the MFRSR-based aerosol retrieval for clear-sky periods and an interpolation of the retrieved column aerosol properties for cloudy periods. The observed weak diurnal variability of SSA and ASP at the surface and the close association of the surface intensive aerosol properties with their column counterparts form the basis of such interpolation. The approach is evaluated by calculating the corresponding clear-sky total, direct and diffuse fluxes at five wavelengths (415, 500, 615, 673 and 870 nm) and compare them with the observed fluxes. The aerosol properties provided by this approach are applied for (i) an examination of the statistical relationship between spectral (visible range) and broadband values of the total normalized cloud radiative forcing and (ii) an estimation of the fractional sky cover. Data collected during 13 days with single-layer cumulus clouds observed at U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site during summer 2007 are applied to illustrate the performance and application of this approach.

Passive infrared spectral sensors (7-14 um) measure brightness temperature along a line of sight, and from these measurements the presence of a vapor cloud is deduced. How important are atmospheric temperature fluctuations due to turbulence on the detection of vapors? We developed a stochastic simulation that uses the MODTRAN program to explore this question. We were surprised to find that although temperature brightness fluctuations are not insignificant compared to state-of-the-art sensor's noise (modeled as uncorrelated white noise) the effect on detection was very small because turbulence noise is spectrally correlated and thus its effect was largely removed with a regression algorithm. In this work we do not address the detection limit due to atmospheric interferences whose effect on detection limit may is severe.

This paper discusses recent advances in the simulation of spectral scenes with partial cloud cover. We examine the effect of broken cloud fields on the solar illumination reaching the ground. Application of aerosol retrieval techniques in the vicinity of broken clouds leads to significant over-prediction of aerosol optical depth because of the enhancement of visible illumination due to scattering of photons from clouds into clear patches. These illumination enhancement effects are simulated for a variety of broken cloud fields using the MCScene code, a high fidelity model for full optical spectrum (UV through LWIR) spectral image simulation. MCScene provides an accurate, robust, and efficient means to generate spectral scenes for algorithm validation. MCScene utilizes a Direct Simulation Monte Carlo approach for modeling 3D atmospheric radiative transfer (RT), including full treatment of molecular absorption and Rayleigh scattering, aerosol absorption and scattering, and multiple scattering and adjacency effects, as well as scattering from spatially inhomogeneous surfaces.

Laser sensing is an effective way of studying optical properties of various atmospheric structures. If we consider strongly scattering media, like clouds, there arises the necessity of taking into account the effects of multiple scattering which changes the space and time characteristics of the light pulse. The Monte Carlo method is the most convenient one for obtaining practical results in such problems. In this paper two problems were solved. One is constructing an adequate optical model of crystal clouds taking into account optical anisotropy of the medium. The other is Monte Carlo modeling of laser radiation transfer in such a medium. The form and duration of light pulses reflected by clouds (lidar returns) are obtained by the Monte Carlo method in the case of single layer continuous crystal cloud and double layer continuous cloudiness (a crystal cloud of highest level is located above a drop cloud).

Shape is a key parameter of aerosol particle. Light scattering and imaging via microscope are conventional measurement ways for detecting aerosol particle shape, but their conclusion can't be certified by themselves. A new self-consistent method combining scattering and imaging is tried. A concentric hollow spherical chamber is the core portion to get signal, where flying single aerosol particle along diameter perpendicular to horizontal plane intersects with laser beam at the chamber centre. Photo of aerosol particle is gained by CCD after amplified, simultaneously, scattering of the same particle is transferred by optical fibers and conversed by PMT. The intensity and polarization of scattering by single fibre cotton are analysed according self-programming wave theory, and the reason for difference of signal is declared compared with photos by CCD. The result shows that the method is reliable.

A methodology for detecting potentially hazardous storms over South Africa using meteorological satellite imagery from Meteosat Second Generation (MSG)/SEVIRI is presented. An index indicative of the hazardous potential of a storm is defined to aid in the identification of affected geographical areas and to quantify the destructive potential of the detected storm. The data from MSG/SEVIRI infrared channels is employed to analyze potentially hazardous storms. A hazardous potential index (HPI) is generated through the use of image processing techniques such as cloud masking, cloud tracking and an image-based analysis of the constituent elements of a severe convective storm.

Euroskyrad (ESR) is a network of European groups that focus their research on the atmospheric aerosols by applying the Skyrad inversion algorithm indistinctly to Cimel CE318 and Prede POM sky - sun radiometers. This study addresses the performance of ESR new algorithms in comparison to AERONET for aerosol optical depth retrieval from direct sun measurements. More specifically, we have applied the ESR algorithms (ESR.pack, modes 1 and 2) to a Cimel CE318 and Prede POM-01L simultaneous database obtained at Valencia (Spain) and compared the resultant aerosol optical depth with the AERONET retrievals. The results obtained with Cimel agree with AERONET within 0,009 - 0,011 and 0,001 - 0,007 (ESR modes 1 and 2, respectively) depending on wavelength. Furthermore, a comparison between aerosol optical depth obtained from Cimel and Prede radiometers is also possible by using the same code, and the results agree better than 0,003 - 0,006 independently of ESR mode. Finally, the comparison of AOD obtained with Prede/ESR against Cimel/AERONET shows a reasonable deviation for mode 1 (0,006 - 0,012) and a very good agreement for mode 2 (0,004 - 0,007). In general these differences fall within the nominal AERONET uncertainty of 0.01-0.02 for field instruments.

It may be difficult to distinguish the dust and clouds especially for low clouds over ocean from satellite, due to that the dust aerosols can pass through the ocean. The dust clouds are comprised of dust aerosol particles, while the clouds are comprised of water droplets or ice particles. In this paper, using the Mie scatter theory and HITRAN 2008 aerosol complex refractiive index datum, the extinction coefficient, single scattering albedo and asymmetry factor of dust aerosols, water droplets and ice particles which satisfy the log-normal distribution, are calculated at different infrared wavelength and with different particle radius. The results show that the infrared properties of dust aerosols and cloud droplet particles are significantly different. At 10~12μm, the infrared radiance absorbed by ice particles and water droplets are greater than those by the dust aerosols. The extinction coefficient and the asymmetry factor will increase with the particle radius. When the effective particle radius is lower than 2μm, the single scattering albedo will increase with the particle radius. Those different infrared properties provide some information for detecting the dust aerosols and clouds and retrieving the dust or cloud effective particle radius and single scattering albedo from thermal infrared radiance. It is also very important and very meaning to choose some bands for satellite observation by analyzing the infrared scatter properties of dust aerosols, water droplets and ice particles.

A VDI/DIN guideline for passive FTIR spectrometry is under development. The topics will be: Basics of the techniques: principles for the detection of gaseous clouds and exhaust composition, radiative transfer model, radiative temperature, noise equivalent column density and detection limits; Measurement systems: Fourier transform spectroscopy, Michelson interferometers, measurement configurations, spectrometers with one detector element, scanning systems, scanning imaging systems, spectrometers with a detector array; Calibration: radiometric calibration, system calibration; Remote sensing of gases at ambient temperature: basics, identification of gases, quantifications, application examples; Remote sensing of gases at high temperatures: basics, quantification of gas temperature, quantification of composition, application examples; Remote sensing of gases by means of solar radiation: basics, measurement performance, data analyses, application examples.

Methane (CH4), a significant atmospheric trace-gas, controls numerous chemical processes and species in the troposphere and stratosphere and is also a strong greenhouse gas with significantly adverse environmental impacts. Since the SCIAMACHY on the Envisat was in orbit since 2002, CH4 measurements at a regional scale became available. This study (1) firstly improved the spatial resolution of 0.5°×0.5° lat/lon grid data provided by University of Bremen IUP/IFE SCIAMACHY near-infrared nadir measurements using the scientific retrieval algorithm WFM-DOAS to 0.1°×0.1° lat/lon with the ordinary Kriging method, (2) then analyzed the spatial-temporal characteristics of atmospheric CH4 concentration in the Yangtze River basin (YRB), China from 2003 to 2005, (3) finally analyzed the relations with the main environmental factors: the precipitation from GSMaP MVK+ 0.1x 0.1 lat/lon degree grid data and the temperature from 147 meteorological stations in the YRB. The analysis shows that atmospheric methane concentration has significant and obvious characteristics of the spatial distribution of the inter-annual cycle fluctuations and seasonal characteristics during the year, and points out that the temperature is the main impact factor.

A methodology is presented to derive a time series of Precipitable Water Vapour (PWV) maps from interferometric Synthetic Aperture Radar (SAR) data. Generally, information on PWV spatial distribution provided by SAR interferomeetry (InSAR), even if characterized by a high spatial resolution, is updated with a temporal frequency depending the satellite revisiting cycle of the InSAR sensor. The methodology is based on the use of independent GPS measurements of PWV to set the unknown bias resulting from the unwrapping process in each unwrapped interferometric phase. The main advantage of this methodology is that calibrated PWV maps can be derived from each stack of SAR interferograms. This allows the merging of PWV time series obtained over the same area by different SAR sensors and along different satellite orbits. As a result, the updating frequency is reduced from the satellite revisitng cycle to a few days.

Atmosphere water vapour remains the largest limitation in high precision applications that make use of microwave signals as Interferometric Synthetic Aperture Radar (InSAR). In the last decade several methods like GPS (Global Positioning System), MERIS (MEdium Resolution Imaging Spectrometer) and NWP (Numerical weather prediction) models were studied with the aim of obtaining a reliable water vapour product of high spatial and temporal resolution to reduce the impact that the water vapour have on microwave signals. Water vapour product derived from the optical sensor MERIS may be used to mitigate the troposphere effects in applications like InSAR and used to improve NWP models. In this paper the water vapour derived from MERIS and GPS are compared, and a methodology to combine GPS and MERIS is present.

In this work we present the results of an experiment aiming to measure and model atmospheric delay by means of GPS, Weather Research and Forecasting (WRF) model and Synthetic Aperture Radar Interferometry (InSAR). Examples of maps of the atmospheric delay over the region of Lisbon are shown.

For a long period of time FHR is developing millimetre wave radars for airborne remote sensing applications, namely at 35 GHz and 94 GHz. While for these applications generally a high bandwidth is used to allow an adequate range resolution, the requirements for cloud radars are more directed towards an ultimate sensitivity and long range. Based upon this expertise investigations were done to develop a cloud radar at 220 GHz, which should be used simultaneously with respective radars at 35 GHz and 94 GHz. To gain experience with this topic, a 94 GHz-radar, which was formerly used for propagation experiments over long range, was modified and measurements on clouds were conducted. The radar to be developed shall mainly be used for investigations on snow clouds over relatively short range, and is not intended to be able to characterize Cirrus type clouds at high altitude.