The shape of water-leaving reflectance spectra in the near infrared range 700-900nm is almost invariant for turbid waters and has been analysed and tabulated as a similarity spectrum by normalisation at 780nm. This similarity spectrum is used here for the quality control of seaborne reflectance measurements and for the improvement of sky glint correction. Estimates of the reflectance measurement error associated with imperfect sky glint correction from two different wavelength pairs are shown to be nearly identical. A demonstration of residual reflectance correction for data collected in cloudy, high wave conditions has shown that this correction removes a large source of variability associated with temporal variation of the wave field. The error estimate applied here to seaborne measurements has wide-ranging generality and is appropriate for any water-leaving reflectance spectra derived from seaborne, airborne or satellite borne sensors provided suitable near infrared bands are available.

An algorithm is presented to correct SAC-C MMRS imagery in the visible for atmospheric and surface effects. These effects are due essentially to gaseous absorption, molecule and aerosol scattering, and Fresnel and whitecap reflection. Aerosol scattering is determined from measurements in the spectral bands centered at 815 and 1,625 nm, where the ocean is assumed to be totally absorbing. The information is then extrapolated to the ocean-color bands, centered at 490, 550, and 660 nm. The algorithm's theoretical performance, evaluated for varied geometry, surface conditions, aerosol loading, and mixtures of continental and maritime aerosols, is about ±0.0005 (r.m.s) on the aerosol path reflectance. This accuracy meets the requirements for ocean-color applications, at least in open waters. The algorithm is applied to MMRS imagery acquired off the Valdes Peninsula, Argentina. Compared with SeaWiFS estimates of marine reflectance, the MMRS values are too low and noisy, especially at 660 nm. The discrepancies may be due to non-zero marine reflectance at 815 nm, radiometric calibration errors, and to the large noise in the data (lack of sensitivity in the atmospheric correction bands). The results demonstrate the potential of MMRS for quantitative ocean-color remote sensing in coastal regions of South America.

The vertical distribution of absorbing aerosols affects significantly the reflectance of the ocean-atmosphere system. The effect, due to the coupling between molecule scattering and aerosol absorption, is important in the visible, especially in the blue, and becomes negligible in the near-infrared. Differences between top-of-atmosphere reflectance obtained with distinct vertical distributions increase with the sun, and view zenith angle, and the aerosol optical thickness, and with decreasing scattering albedo, but are practically independent of wind speed. In atmospheric correction algorithms, these differences are directly translated into errors on the retrieved water reflectance. They may reach large values even for small aerosol optical thickness, preventing accurate retrieval of chlorophyll concentration. A method has been developed to estimate aerosol altitude from data in the oxygen A-band of the MERIS, and POLDER sensors. The method is sufficiently sensitive to improve retrievals of water reflectance and chlorophyll concentration in the presence of absorbing aerosols.

Ocean-color remote sensing from space is currently limited to cloud-free areas. Consequently, the daily ocean coverage is 15-20%, and weekly products show no information in many areas. This limits considerably the utility of satellite ocean color observations for operational oceanography. Global coverage is required every three to five days in the open ocean and at least every day in the coastal zone. In view of the requirements for spatial coverage, and of the effects of clouds on observations of ocean color, an algorithm is proposed to estimate marine reflectance in the presence of a thin or broken cloud layer. The algorithm's theoretical basis is that cloud reflectance at some near-infrared wavelength may be accurately extrapolated to shorter wavelengths, whatever the cloud geometry, without any additional information. The interaction between cloud droplets and molecules, in particular, follows a λ^-4 law. On the contrary, estimating aerosol scattering requires at least a measurement of its spectral dependence. Applying the algorithm to actual satellite ocean color imagery, a substantial gain in ocean coverage is obtained. The oceanic features retrieved below the clouds exhibit continuity with the adjacent features in clear areas. The daily ocean coverage is expected to be increased to up to 50% with the proposed algorithm, allowing one to resolve better phytoplankton blooms in the open ocean and "events" linked to wind forcing in the coastal zone. This could lead to important new information about the temporal variability of biological processes.

The paper compares GLI-derived estimates obtained under "version 2" GLI standard atmospheric correction algorithm with in situ measured data collected by SIMBADA handheld above-water radiometer, intending the evaluating the performance of the algorithm which includes empirical absorptive aerosol correction as well as sun glint correction. Over 395 match-up data, average estimation error (difference between GLI-derived and SIMBADA-measured data) in normalized water-leaving radiance (nL_W) is 0.3 μW/cm²/nm/sr in 412 and in 443 nm bands, showing improvement from version 1 GLI atmospheric correction by 10-30 %, whereas estimation bias is reduced significantly. The GLI-derived aerosol optical thickness (AOT) in 865 nm band show 0.1 RMS error against SIMBADA measurement on average, whereas Angstrom exponent estimate shows significant bias, suggesting potential calibration offset among GLI near-infrared bands. Despite relatively large scattering in nL_W match-up analysis, comparison between GLI chlorophyll a concentration estimates and SIMBADA-derived estimation show highly correlated and consistent relation. This will suggest that fluctuations in nL_W estimate are systematic over GLI visible channels although the nature of the variability requires further investigation.

Current ocean color algorithms based on remote-sensing reflectance spectra, R_rs(λ), overestimate chlorophyll a concentrations, Chl, and particulate backscattering coefficients, b_bp(λ), in optically shallow oceanic waters due to increased bottom reflectance. Since such regions often contain important ecological resources and are heavily influenced by human populations, accurate estimates of Chl and b_bp(λ) are essential for monitoring algal blooms (e.g. red tides), detecting sediment resuspension events and quantifying primary productivity. In this study, a large synthetic data set of 500 R_rs(λ) spectra is developed to examine limitations of ocean color algorithms for optically shallow waters and to develop alternative algorithms that can be applied to satellite (e.g. SeaWiFS and MODIS) and aircraft ocean color sensor data. R_rs(λ) spectra are simulated using a semi-analytic model for optically shallow waters. The model is parameterized with sand bottom albedo spectra, ρ(λ), using a wide range of chlorophyll a concentrations (0.03-30 mg m^-3), bottom depths (2-50m) and bottom albedos (ρ(550)=0.01-0.30) to provide a robust data set that accurately represents and complements shipboard R_rs(λ) data from the Gulf of Mexico and Bahamian waters. The accuracy of a remotely-based technique developed recently from shipboard R_rs(λ) data is tested on the synthetic data for identifying waters with bottom reflectance contributions at R_rs(555) greater than 25%. Limitations and improvements regarding this method are discussed.

We study two types of contamination of Ocean Color data related to the presence of sea ice. The first type, referred to as the adjacency effect, is the contamination of the radiance from the intended target by photons scattered in atmosphere towards the sensor but originating from a bright object such as sea ice nearby the target. The second type results from the presence of sub-pixel sea ice. In the case of the adjacency effect, the contribution of the icy environment to the top-of-atmosphere signal in the visible is not fully removed by the atmospheric correction algorithm, leading to an overestimation of the water-leaving reflectance. This is due to the strong spectral increase of atmospheric scattering with decreasing wavelength. The adjacency effect being more important at short wavelengths, the chlorophyll estimates based on the blue-to-green ratio will tend to decrease as the field of view approaches the ice edge. Conversely, contamination by sub-pixel sea ice results in an underestimation of the water-leaving reflectance, especially in the blue domain, and consequently to an overestimation of the chlorophyll concentration. The magnitude of the errors depends on the type of ice contaminating the pixel. It is more important for ice with high reflectance ratios for the wavebands 765 to 865 nm. Absolute error on the water-leaving reflectance up to 0.7% was observed, which is not acceptable for Ocean Color applications intending inversion of inherent optical properties from the absolute radiance, and for validation and vicarious calibration activities.

The global significance of the coastal waters off the west coast of Vancouver Island British Columbia was formally recognized by the United Nations' Man and the Biosphere (MAB) program on May, 5, 2000 by the creation of the Clayoquot Sound Biosphere Reserve. The marine coastal ecosystem of this reserve totals approximately 84,242 hectares. The inherent optical properties of these waters were measured during a fifteen day, 21 station cruise in the summer of 2004 and were synchronized with the daily MODIS Aqua satellite over flights. The depth of maximum backscatter were compared to the ratio of absorption of particulate and color dissolved organic matter (CDOM) and related to remotely sensed estimates of Chl-a. The relationships of these parameters are compared between stations within the Clayoquot Sound and off the coast. This investigation highlights the contribution of the functional proportion of particulate and CDOM in over estimates of Chl-a from satellite remote sensing. The spatial correlation of this functional relationship is however linked to observed patterns of coastal ocean color.

We present two algorithms for the retrieval of 1) vertical light penetration and 2) horizontal visibility in coastal waters using ocean color data. The Secchi depth, a proxy to vertical visibility or water transparency, is related to the former two properties and can be retrieved from two irradiance reflectances. The algorithm development includes the use of classical approximations in marine optics, sensitivity analyses based on radiative transfer calculations, and the use of an extensive in situ optical data set. Finally, match-ups between in situ measurements of the Secchi depth and ocean color data were used for the parameterization of the operational algorithm. Maps of Secchi depths are presented over different coastal regions.

Previously, it was shown that it is possible to separate the elastic scattering from the chlorophyll fluorescence signal using a polarization discrimination technique. The separation procedure depends however fundamentally on the degree of polarization of the water leaving radiance. In this paper, we study this dependence by simulating the total and polarized reflectance of waterleaving radiances originating from elastic scattering in case 1 and case 2 waters, by superimposing upon these reflectances the contribution of known fluorescence spectra, and by using our procedure to invert the resulting data back into fluorescence spectra. It is shown that the results of this retrieval compare well with the input values of fluorescence spectra for a wide range of underwater light scattering conditions. We show also that height baseline method, which is frequently used for the retrieval of fluorescence, can lead to significant overestimation of fluorescence for coastal zone conditions. The effects of different depths, surface roughness and bottom albedo are also analyzed. It is shown that in most cases fluorescence can be successfully retrieved with acceptable accuracy.

In an earlier work, we have proposed a concept for estimation of ocean optical properties with a multiple field-of-view bathymetric lidar. In this paper, we consider an implementation of this idea using SHOALS. The SHOALS design uses two receivers for depth measurement: a shallow-water, APD receiver with an 18 mrad FOV; and a deep-water PMT receiver with a 40 mrad FOV. They simultaneously record the optical power returned from a single pulse of the laser, and consequently provide the desired measurements. Here, we present an algorithm for the estimation of inherent optical properties (IOPs) in the upper ocean layer which is based on "multiple-forward-single-backscattering" model of the returned power, and an analytical solution to the radiative transfer equation (RTE) for finite sounding beam propagation in the small-angle-scattering approximation. Using this algorithm, we have developed an approach for estimation of the backscattering coefficient, the beam attenuation coefficient, the single-scattering albedo, and the VSF asymmetry coefficient, by fitting simulated waveforms to actual data measured by the two receivers. We also present an approach for improvement in estimates of bottom reflectance which compensates for pulse stretching induced by angle of incidence effects.

Estimation of water column optical properties and seafloor reflectance (532 nm) is demonstrated using recent SHOALS data collected at Fort Lauderdale, Florida (November, 2003). To facilitate this work, the first radiometric calibrations of SHOALS were performed. These calibrations permit a direct normalization of recorded data by converting digitized counts at the output of the SHOALS receivers to input optical power. For estimation of environmental parameters, this normalization is required to compensate for the logarithmic compression of the signals and the finite frequency of the bandpass of the detector/amplifier. After normalization, the SHOALS data are used to estimate the backscattering coefficient, the beam attenuation coefficient, the single-scattering albedo, the VSF asymmetry, and seafloor reflectance by fitting simulated waveforms to actual waveforms measured by the SHOALS APD and PMT receivers. The resulting estimates of these water column optical properties are compared to in-situ measurements acquired at the time of the airborne data collections. Images of green laser bottom reflectance are also presented and compared to reflectance estimated from simultaneously acquired passive spectral data.

Small maritime targets, e.g., periscope tubes, jet skies, swimmers and small boats, are potential threats for naval ships under many conditions, but are difficult to detect with current radar systems due to their limited radar cross section and the presence of sea clutter. On the other hand, applications of lidar systems have shown that the reflections from small targets are significantly stronger than reflections from the sea surface. As a result, dedicated lidar systems are potential tools for the detection of small maritime targets. A geometric approach is used to compare the diffuse reflection properties of cylinders and spheres with flat surfaces, which is used to estimate the maximum detectable range of such objects for a given lidar system. Experimental results using lasers operating at 1.06 μm and 1.57 μm confirm this theory and are discussed. Small buoys near Scheveningen harbor could be detected under adverse weather over more than 9 km. Extrapolation of these results indicates that small targets can be detected out to ranges of approximately 20 km.

The description of radar propagation in the presence of the evaporation duct has proven to be a difficult problem in both littoral and open ocean environments. To properly characterize the propagation of a radar beam at low elevation angles, the evaporation duct must be located and scattering properties quantified. The two key elements defining an evaporation duct are the gradients in density and specific humidity. The gradients of the neutral density are determined from the rotational Raman temperature profile. The profile of water vapor is measured directly from the vibrational Raman scattered returns. High spatial resolution and high temporal resolution measurements of water vapor and temperature are required to accurately describe the evaporation duct. Raman lidar techniques can provide these measurements continuously with high accuracy and high resolution so the development of the evaporation duct can be studied. A detailed simulation of a Raman lidar has been developed and applied to a near horizontal path, to examine the expected accuracy for high vertical resolution profiles. The simulation also allows various atmospheric scenarios to be investigated and analyzed. The evaporation duct is an atmospheric phenomenon that causes radar propagation to remain trapped in the surface layer. The duct can be thought of as a waveguide that bends and reflects the radar beam along a path effectively trapping it and guiding it over long distances. This is a major problem for radar propagation paths in both littoral and open ocean environments. Moreover, ducting skews details of radar returns such that radar objects are hidden, or are detected at unexpected distances, or may appear with apparent cross-sections and speeds much different than their actual values.

Harmful algal blooms (HABs) have impacts on coastal economies, public health, and various endangered species. HABs are caused by a variety of organisms, most commonly dinoflagellates, diatoms, and cyanobacteria. In the late 1970's, optical remote sensing was found to have a potential for detecting the presence of blooms of Karenia brevis on the US Florida coast. Due to the nearly annual frequency of these blooms and the ability to note them with ocean color imagery, K. brevis blooms have strongly influenced the field of HAB remote sensing. However, with the variability between phytoplankton blooms, heir environment and their relatively narrow range of pigment types, particularly between toxic and non-toxic dinoflagellates and diatoms, techniques beyond optical detection are required for detecting and monitoring HABs. While satellite chlorophyll has some value, ecological or environmental characteristics are required to use chlorophyll. For example, identification of new blooms can be an effective means of identifying HABs that are quie intense, also blooms occurring after specific rainfall or wind events can be indicated as HABs. Several HAB species do not bloom in the traditional sense, in that they do not dominate the biomass. In these cases, remote sensing of SST or chlorophyll can be coupled with linkages to seasonal succession, changes in circulation or currents, and wind-induced transport--including upwelling and downwelling, to indicate the potential for a HAB to occur. An effective monitoring and forecasting system for HABs will require the coupling of remote sensing with an environmental and ecological understanding of the organism.

Accurate detection of highly toxic red tide algal blooms in coastal turbid waters has been challenging with currently existing spectral and bio-optical methods applied to satellite ocean color imagery, mainly because of the eventual interference of absorbing and scattering properties of dissolved organic and particulate inorganic matters with these methods. In the present study, we have presented a new red tide index (RI) technique to effectively identify the highly toxic dinoflagellate Cochlodinium polykrikoides (p) blooms in the Korean South Sea and neighboring waters. The effectiveness of this technique was evaluated using in-situ bio-optical observations and SeaWiFS ocean color imagery acquired during two bloom episodes on 19 September 2000 and 28 September 2003. The findings revealed that chlorophyll-a estimated through the application of OC-4 bio-optical algorithm to the SeaWiFS imagery falsely identified Cochlodinium.p blooms in areas abundance in colored dissolved organic and particulate inorganic matter constituents around coastal areas and river mouths. In contrast, red tide index was found to provide more accurate and comparable spatial Cochlodinium.p patterns consistent with in-situ observations, proving to be the best method for providing improved capability of detecting, predicting and monitoring of Cochlodinium.p bloom dynamics in clear oceanic waters and high scattering and absorbing waters off the Korean coast.

MODIS medium-resolution (250- and 500-m) bands were successfully used to detect and map the distribution of a harmful phytoplankton bloom (HAB) in the Paracas Bay, Peru, that caused economic losses estimated at about $28.5 million. A Red-Green-Blue combination of bands 1, 4 and 3 was used to visually distinguish the HAB while the turbidity index, a semi-quantitative measure of the amount of particulate material in the near-surface water, was used to estimate the intensity of the HAB. The turbidity index was inversely correlated with oxygen concentration in the bay. Temporary anoxia caused by the HAB was probably the main mechanism causing fish kills. The 250-m resolution provided by MODIS bands 1 and 2 is essential to detect localized HABs in coastal areas. While turbidity is not specific to algal blooms, it is a quantitative estimate of the intensity of the bloom once the existence of the bloom is detected by the RGB images.

Satellite remote sensing imagery is being used to identify and characterize upwelling conditions on the coast of Washington State, with an emphasis on detecting ocean features associated with harmful algal bloom events. Blooms of phytoplankton, including the domoic acid-producing diatom Pseudo-nitzschia, appear to be associated with a semi-permanent eddy bordering Washington and British Columbia that is observed in satellite imagery during extended upwelling events. Strong upwelling conditions may act as a barrier to movement of these blooms onshore. Using NOAA AVHRR temperature imagery, edge detection algorithms are being developed to define the strength, location and extent of the surface temperature expression of upwelling along the coast of Washington. The edge detection technique uses a simple kernel-based gradient method that compares temperatures of pixels at a user-specified distance. This allows identification of larger features with subtle edges. The resulting maximum-gradient map is then converted to a binary format with a user-specified temperature threshold. Skeletonization and edge-linking algorithms are then employed to develop final map products. The upwelling edge detection maps are being examined in relation to harmful algal bloom events that have occurred along the coast.

Since 1997, the ENEA Lidar Fluorosensor (ELF) carries out measurements of phytoplanktonic pigments, in vivo phytoplankton fluorescence yield, chromophoric dissolved organic matter (CDOM) and photosynthetically active radiation (PAR) in the coastal zone of Antarctica, one of the more interesting but less investigated environment of our planet. With respect to ocean color satellite radiometers, ELF is insensitive to clouds, free from atmospheric correction and accurate also in case II waters. Nevertheless, in order to take advantage of both the synoptic view of the satellite radiometers and the "sea truth" of the lidar fluorosensors, ELF measurements have been used to calibrate a chlorophyll-a (Chl-a) bio-optical algorithm and to develop a CDOM bio-optical algorithm, both based on the radiometer-derived water leaving radiance, and to elaborate a new Chl-a bio-optical algorithm based on the radiometer-derived sun-induced Chl-a fluorescence. In fact, ELF data are more suitable to that purpose than usual in situ sampling because their geographic coverage and spatio-temporal resolution are closer to image extent and pixel size/time, respectively, of the satellite products. ELF-calibrated Chl-a and ELF PAR have then been used as input variables for a vertically generalized production model tuned in Antarctic waters. As a consequence, a new primary production regional model for the Southern Ocean is available. Those results, from one hand, help in understanding extensions and dynamics of coastal processes, like phytoplankton blooms, from the other hand, indicate that standard algorithms can misestimate the algal biomass.

The ANTARES network seeks to understand the variability of the coastal environment on a continental scale and the local, regional, and global factors and processes that effect this change. The focus are coastal zones of South America and the Caribbean Sea. The initial approach includes developing time series of in situ and satellite-based environmental observations in coastal and oceanic regions. The network is constituted by experts that seek to exchange ideas, develop an infrastructure for mutual logistical and knowledge support, and link in situ time series of observations located around the Americas with real-time and historical satellite-derived time series of relevant products. A major objective is to generate information that will be distributed publicly and openly in the service of coastal ocean research, resource management, science-based policy making and education in the Americas. As a first stage, the network has linked oceanographic time series located in Argentina, Brazil, Chile and Venezuela. The group has also developed an online tool to examine satellite data collected with sensors such as NASA's MODIS. Specifically, continental-scale high-resolution (1 km) maps of chlorophyll and of sea surface temperature are generated and served daily over the web according to specifications of users within the ANTARES network. Other satellite-derived variables will be added as support for the network is solidified. ANTARES serves data and offers simple analysis tools that anyone can use with the ultimate goal of improving coastal assessments, management and policies.

In this work, we present a new method for dynamic assignment of the boundaries of the ecological provinces of the North West Atlantic. The results are compared with the distribution of diatoms in the study area. Both analyses rely on ocean-colour data for the region. Diatoms were identified using remoteely-sensed data on the basis of their species-dependent absorption characteristics, which were embedded in a simple reflectance model(Sathyendranath et al., 2004). Maps of diatom distributions were produced for the area. Satellite-derived chlorophyll biomass and sea surface temperature (MODIS data) for the same period were used to redefine, in a dynamic way, the static borders of the ecological provinces (Sathyendranath et al., 1995; Longhurst 1998). The analyses were carried on two-week composite images, at different times of the year (April-May, July and October), to examine seasonal variability in the boundaries. The boundaries of provinces and the occurrence of diatoms were spatially coherent. Diatoms were favoured in rich waters on the continental shelf and in cold waters at high latitudes. In provinces labelled as oligotrophic (subtropical gyre and Gulf Stream), very negligible fractions of diatoms were found at any time of the year.

Remote sensing has improved our capacity to study the passage of hurricanes in the coastal zone. These transient events lead to upwelling of cold, nutrient-rich waters into the mixed layer that promotes increased primary production and therefore higher phytoplankton biomass. The Northwest Atlantic, an area with rich fisheries resources, experiences several hurricanes each year. We report on the response of the fields of chlorophyll and temperature to the passage of Hurricane Fabian using satellite images of ocean colour (SeaWiFS, analysed with local modifications to the standard NASA method) and sea-surface temperature (NOAA/AVHRR). Data from a band of 700 km width along the storm track were extracted from composite images of the fields before and after the storm passage. Concurrent changes in the temperature and chlorophyll-a (Chl-a) fields were observed along and across the storm track. There is an imbalance in the distribution of the differences in both SST and Chl-a, with changes being smaller on the left side of the storm path, than on the right side. We also examined changes in the taxonomic composition of phytoplankton communities promoted by the physical forcing, since it is known that diatoms have fast growth rates in relatively turbulent and nutrient-rich waters. This step was carried on using an algorithm that allows to distinguish between diatoms and other phytoplankton populations. Our results showed that after the passage of Hurricane Fabian, a new phytoplankton succession cycle was initiated, led by diatoms.

Sensitivity experiments conducted with the MIT ocean general circulation model reveal the potential influence of solar radiation absorbed by phytoplankton on the thermal structure and currents of the equatorial Pacific Ocean. In the model, vertical attenuation of solar radiation is parameterized as a function of chlorophyll pigment concentration, the major variable affecting turbidity in the euphotic zone. To isolate turbidity effects, the model is run from 1948 to 2001 with either a constant minimum pigment concentration of 0.02 mgm^-3 during the entire period or spatially and temporally varying pigment concentration from the Sea-viewing Wide Field-of-view Sensor during 1997-2001. The two model runs are compared for 2001, a relatively normal year following the strong 1997-1998 El Nino and subsequent La Nina. Due to phytoplankton-radiation forcing, equatorial sea surface temperature is decreased by 0.3K on average annually between 100W and 160W, but the negative temperature change is more pronounced in sub-surface layers, reaching -1.5K at 110W. In that region, heat trapping by phytoplankton causes the mixed layer to shallow and isotherms to shoal toward the equator, generating geostrophic currents that enhance the south equatorial current. These surface currents diverge north and south of the equator as they progress westward, creating equatorial divergence, convergence at the level of the equatorial undercurrent, and upwelling, explaining the change in thermal structure. The equatorial undercurrent is strengthened by as much as 4 cms^-1 at its core. The findings support previous results obtained with the MHI Ocean isoPYCnal general circulation model and pigment concentration from the Coastal Zone Color Scanner. They indicate that biology-induced buoyancy my play a significant role in the equatorial Pacific Ocean circulation and suggest the existence of a biophysical feedback mechanism that contributes to maintaining the cold tongue in the eastern equatorial Pacific Ocean, with implications for inter-annual variability associated with El Nino.

The Yellow River is the second largest river in China, and is famous for its suspended riverbed, frequent shifts of its river routine and huge amount of sediments. The Yellow River Delta also has unique evolutionary features-its coastal line is either being rapidly silted or eroded. The high rates of sediments transport and deposit make the Yellow River mouth the only estuary in the world where new land is being created at a rate of more than 20km²/yr. At the same time, oceanic waves and currents are eroding the coastal line. By the intensive interaction of the river flow and the oceanic waves and currents, a series of evolutionary process of the coastal line such as silting forward, eroded back, raised riverbed and routine change of the Yellow River have been occurring since 1976 when the Yellow River changed its routine into the new Qingshuigou Routine. To protect the non-stable and vulnerable Delta and to manage its coastal line, the paper suggests that it is necessary and efficient to study the evolution and change of coastal line of the yellow river delta using integrating remote sensing (RS) and GIS. The authors interpreted and analyzed 20 maps of MSS and TM imagines pictured from 1976 to 1996 by GIS. The rate of silting and eroding of the coastal line are calculated, the evolutionary principles of the coastal line are determined, and eventually the evolutionary trends are predicted in the paper.

The main subject of presented work is the development of the family of fiber-optic chemical sensors for admixtures detection in air or in water. The experimental results are presented in details for the sensors for NH₃, H₂S and RSH with the appropriate models for operation in gas and liquid media. These sensors could be used for remote control of the common pollutions in environment, or for the measurements of the admixtures in different processes in industry. The production of these sensors for the detection and measurement of the concentrations of toxic gases yields rather simple and inexpensive tools for laboratory and industrial use.

During spring and summer 2004, intensive field campaigns were conducted in the Eastern English Channel. This region is characterized by relatively intense phytoplankton blooms, low bathymetry, strong tide ranges and great river inputs. The sampling period accounts for episodic blooms of prymnesiophyceae Phaeocystis globosa and diatoms. Hyperspectral radiometric measurements (TRIOS; 350-950 nm, with a 3 nm spectral resolution) were concurrently performed with water sampling for biogeochemical and optical characterization. The remote sensing reflectance, R_rs, is analyzed in conjunction with variation of the water composition. We particularly focus on the capability to identify some phytoplankton species from R_rs in this very variable environment. Different methods, based on multispectral and hyperspectral data are tested and compared for that purpose. We show that no R_rs ratio allows to discriminate between diatoms and Phaeocystis. In contrast, the derivative analysis applied to hyperspectral data stresses large differences in some part of the R_rs spectra collected in diatoms or Phaeocystis dominated waters.

The Southern Bight of the North Sea is characterised by a large influence of river inputs, which results in eutrophication of the area. High concentrations of plankton biomass and suspended matter have been reported for this area, in relation with blooms of different species and resuspension of bottom sediments. In spring the haptophyte Phaeocystis globosa blooms throughout the area reaching up to 30 mg Chlorophyll m-3 or more nearshore. This event is followed in June by red tides of the dinoflagellate Noctiluca scintillans. These blooms are concurrent with different species of diatoms. The strong optical signature of these blooms is clear to human observers making them potentially detectable in satellite imagery. As a first step in this direction, sampling has been carried out in the area, during Phaeocystis and Noctiluca blooms in 2003 and 2004. Phytoplankton pigments and inherent optical properties (particle, detrital and phytoplankton absorption) have been measured spectrophotometrically, and in situ using an ac-9 for total absorption and particle scattering. Field data were compared with optical properties of pure species obtained in laboratory. In parallel, water-leaving reflectance has been also measured. In this paper we characterise the optical signatures of diatoms, Phaeocystis and Noctiluca and their contribution to total absorption. The impact on water-leaving reflectance spectra is evaluated; in order to assess the conditions in which remote sensing can provide information for monitoring the timing, extent and magnitude of blooms in this coastal area.

To enable the production of the best chlorophyll products from SeaWiFS data NOAA (Coastwatch and NOS) evaluated the various atmospheric correction algorithms by comparing the satellite derived water reflectance derived for each algorithm with in situ data. Gordon and Wang (1994) introduced a method to correct for Rayleigh and aerosol scattering in the atmosphere so that water reflectance may be derived from the radiance measured at the top of the atmosphere. However, since the correction assumed near infrared scattering to be negligible in coastal waters an invalid assumption, the method over estimates the atmospheric contribution and consequently under estimates water reflectance for the lower wavelength bands on extrapolation. Several improved methods to estimate near infrared correction exist: Siegel et al. (2000); Ruddick et al. (2000); Stumpf et al. (2002) and Stumpf et al. (2003), where an absorbing aerosol correction is also applied along with an additional 1.01% calibration adjustment for the 412 nm band. The evaluation show that the near infrared correction developed by Stumpf et al. (2003) result in an overall minimum error for U.S. waters. As of July 2004, NASA (SEADAS) has selected this as the default method for the atmospheric correction used to produce chlorophyll products.