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- Front Matter: Volume 7473
- Ocean and Water Color Imagery
- Imaging of the Water Surface
- Imagery and In Situ Water Characterization
- Poster Session
Front Matter: Volume 7473
Front Matter: Volume 7473
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This PDF file contains the front matter associated with SPIE
Proceedings Volume 7473, including the Title Page, Copyright
information, Table of Contents, and the Conference Committee listing.
Ocean and Water Color Imagery
Particulate absorption properties from MODIS ocean color and four in-situ transects in the southeastern Bering Sea shelf during July 2008
Show abstract
Measurements of particulate absorption, namely absorption by phytoplankton and non-algal particles (NAP) are
important components in bio-optical models; only a few studies have been reported for the southeastern Bering Sea. This
study analyzes variability in spectral particulate absorption (aP(λ)) including phytoplankton (aPHY(λ)) and NAP
absorption (aNAP(λ)) from in-situ data in conjunction with ocean color satellite data (MODIS - Moderate Resolution
Imaging Spectroradiometer) along four transects in the southeastern Bering Sea shelf during a cruise in July 2008.
Results obtained indicate that surface aPHY(λ) at 443 nm is higher in middle shelf near the Pribilof Islands with aNAP(λ)
decreasing from north to south across the shelf. Greater than 90% of variability in aP(λ) could be explained by aPHY(λ)
indicating biogenic matter dominates changes in particulate absorption. Good correlations were found between aP(λ),
aPHY(λ) at 443 nm and chlorophyll-a (R2 = 0.65 and 0.80, respectively). aPHY(λ) spectra were highly variable, with larger
variability in blue than red part of the spectrum, indicating change in pigment composition or package effect. MODIS
satellite derived aPHY(λ) using quasi-analytical algorithms (QAA) revealed patterns similar to in-situ absorption data for a
major part of the study area. Inconsistencies seen between in-situ absorption and QAA retrieved satellite absorption
could probably be attributed to temporal differences between in-situ data collection and satellite overpass.
Multivariate interpretation algorithm for water quality in the Baltic Sea
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Subject of the paper is the presentation of the potential of use of multispectral remote sensing data for the investigation
of water quality of large water basins on the example of the monitoring of the Baltic Sea with MERIS data. An
interpretation and inversion scheme for optical satellite data over water has been developed to be used in several national
and international projects to monitor different aspects of water quality. The resulting "Principal Component
Interpretation" algorithm allows an optimized estimation of water constituents: chlorophyll pigment concentrations,
suspended matter concentration and yellow substance concentration as well as optical properties of the water body. From
these are derived secondary parameters like water transparency. In the frame of the international ESA MARCOAST
project this interpretation scheme was developed for a regular (daily) monitoring of the Baltic Sea. Results are uniformly
mapped images and concentration maps of the Baltic Sea area from which are additionally derived weekly, monthly and
seasonal means. The Principal Component Interpretation belongs to the class of model based multivariate interpretation
schemes and is closely related to Neural Networks techniques, but bases on a completely different training procedure. It
makes use of an optimal information redistribution between the spectral bands and relates them to the water constituents.
This kind of estimation allows an simultaneous estimation of expected global estimation accuracy. The regular
monitoring is accompanied by the survey of in-situ ground measurements, which can be used for validation.The paper
will present the bio-optical model which is used for the interpretation of Baltic Sea water.
The basics of the interpretation scheme basing on principal component analysis will be explained and results of the
monitoring of different products will be discussed on examples of a time series in 2008, showing the development and
movement of algae blooms, together with other constituents. The obtained results are critically compared with available
ground measurement.
MODIS and MERIS detection of dinoflagellates blooms using the RBD technique
Show abstract
Harmful Algal Blooms (HABs) can lead to severe economical and ecological impacts particularly in the coastal areas
and can threaten human and marine health. About three-quarter of these toxic blooms are caused by dinoflagellates
species which are well known to migrate vertically. During the day, they migrate up to the surface for photosynthesis,
and consequently, their dense aggregations produce strong bio-optical signals that are detectable by space borne optical
satellite sensors. In this study we use our recently developed low backscattering bloom detection technique, the Red
Band Difference (RBD), to detect various dinoflagellates blooms using both MODIS (Moderate Resolution Imaging
Spectroradiometer) and MERIS (Medium Resolution Imaging Spectrometer) data and present the results which confirm
the potentials of the RBD technique. Here we present examples of bloom detection in waters off Gulf of Mexico,
Monterey Bay, South Africa, and East China Sea.
Wind influence on chlorophyll variability along the Louisiana-Texas coast from satellite wind and ocean color data
Show abstract
QuikSCAT satellite based vector wind data were used to examine wind influence on SeaWiFS derived chlorophyll a
(chlorophyll) surface distribution in the northern Gulf of Mexico waters influenced by the Mississippi and
Atchafalaya Rivers, the largest in North America. Short-term satellite derived wind field revealed a systematic shift
in direction and amplitude of the winds during a cold front passage in March 2002 that strongly influenced the
surface chlorophyll distribution. Both the offshore extent and westward transport of enhanced surface chlorophyll
biomass increased following the frontal passage. Monthly surface wind stress derived from the 12.5 km high
resolution QuikSCAT winds mapped along with SeaWiFS derived surface chlorophyll during a low flow and a
normal river discharge year in 2000 and 2001 indicated the dominant role of river discharge in influencing the
concentration and extent of chlorophyll in the plume and inner shelf waters. However the magnitude and direction of
wind stress strongly influenced the plume orientation and the cross-shelf extent of a coastal band of elevated
chlorophyll. Wind stress also influenced the offshore cross-shelf variability in surface chlorophyll distribution.
Multiangular hyperspectral investigation of polarized light in case 2 waters
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The focus of this work is on the dependence of in situ hyperspectral and multiangular polarized data on the size
distribution and refractive index of the suspended particles. Underwater polarization measurements were obtained using
a polarimeter developed at the Optical Remote Sensing Laboratory of the City College of New York, NY. The degree of
polarization (DOP) of the underwater light field in coastal environments was measured and the water-leaving polarized
radiance was derived. In-water optical properties were also measured with an ac-9 (WET Labs). Absorption and
attenuation spectra are then used to derive information on the dissolved and suspend components in the water medium
which are used in a vector radiative transfer code which provides the upwelling radiance. The model was run for various
values of the refractive index of mineral particles until the modeled DOP matched the measured one. The relationship
between the intensity of the maximum of the DOP and both the refractive index of the mineral particles and the shapes
of their size distributions is analyzed in detail.
Cooperative aquatic sensing using the telesupervised adaptive ocean sensor fleet
Show abstract
Earth science research must bridge the gap between the atmosphere and the ocean to foster understanding of Earth's
climate and ecology. Typical ocean sensing is done with satellites or in situ buoys and research ships which are slow to
reposition. Cloud cover inhibits study of localized transient phenomena such as Harmful Algal Blooms (HAB). A fleet
of extended-deployment surface autonomous vehicles will enable in situ study of characteristics of HAB, coastal
pollutants, and related phenomena. We have developed a multiplatform telesupervision architecture that supports
adaptive reconfiguration based on environmental sensor inputs. Our system allows the autonomous repositioning of
smart sensors for HAB study by networking a fleet of NOAA OASIS (Ocean Atmosphere Sensor Integration System)
surface autonomous vehicles. In situ measurements intelligently modify the search for areas of high concentration.
Inference Grid and complementary information-theoretic techniques support sensor fusion and analysis. Telesupervision
supports sliding autonomy from high-level mission tasking, through vehicle and data monitoring, to teleoperation when
direct human interaction is appropriate. This paper reports on experimental results from multi-platform tests conducted
in the Chesapeake Bay and in Pittsburgh, Pennsylvania waters using OASIS platforms, autonomous kayaks, and multiple
simulated platforms to conduct cooperative sensing of chlorophyll-a and water quality.
New algorithm for MODIS chlorophyll fluorescence height retrieval: performance and comparison with the current product
Show abstract
Our previous studies showed that the Fluorescence Line Height (FLH) product, which uses 3 NIR bands at 667, 678, and
746 nm on the MODerate-resolution Imaging Spectroradiometer (MODIS) sensor, and similar bands on MERIS sensor,
is not reliable in coastal waters because of a peak in the elastic reflectance spectra which occurs due to the confluence of
chlorophyll and water absorption spectra and which overlaps spectrally the chlorophyll fluorescence. This combination
of two overlapping peaks makes fluorescence signal retrieval inaccurate. As a consequence, the present FLH algorithm
significantly underestimates fluorescence magnitudes in coastal waters. To overcome this problem, we introduce a new
and more accurate approach for the retrieval of FLH in turbid waters by the MODIS sensor, which exploits the
correlation between the blue-green and red bands reflectance ratios. We show that by making use of the combined
remote sensing reflectance's (Rrs) at 488nm, 547nm, 667nm and 678nm we can retrieve fluorescence accurately in case
2 waters even for low fluorescence quantum yield when fluorescence magnitudes are low. The derivation and validation
of our algorithm was performed using extensive synthetic datasets which cover a large variability of parameters typical
of coastal waters: with CDOM absorption at 400nm 0-2 m-1, mineral concentration 0-5g/m3 and chlorophyll
concentration of 0.5-100 mg/m3. In addition, we applied this proposed algorithm to MODIS satellite data and compared
it with the traditional FLH algorithm.
Imaging of the Water Surface
Improving coastal altimeter products by a new retracking approach
Show abstract
Satellite altimetry has proved successful as a global tool for monitoring sea surface height, significant wave height and
wind speed. Nevertheless, a global archive of 17 years of raw data from a series of missions is presently unexploited
around the world coastline. This huge amount of unused data can be re-analyzed, improved and more intelligently
exploited, possibly promoting coastal altimetry to the rank of operational service. Operational users interested in
monitoring sea level change and wave conditions in the coastal zone (e.g. for coastal erosion, sediment/pollutant
transport applications) still rely on sparse (and expensive) in situ monitoring stations or poor models. In this work we
present a new approach in the exploitation of altimeter data in the coastal zone (currently impeded by unsuitable
waveform retracking scheme and coarse along-track spatial sampling in the coastal zone, among others). The objective
of this paper is to show how a new, robust, retracking algorithm is able to retrieve with high accuracy physical ocean
parameters from altimeter waveforms in the coastal zone. The main focus lies on retrieving sea surface height in the
coastal zone with the same precision as is achieved in the open ocean. In addition, the retrieval of more accurate
altimeter-derived wave products in the coastal zone is also important as waves are more directly relevant to many
operational applications in the coastal zone.
Radiometric cross-calibration of spaceborne scatterometers: first results
Show abstract
The main application of a scatterometer is the determination of the wind speed and direction at the sea surface. This
is achieved by measuring the radar backscattering coefficient in three different directions and inverting these measurements
using a geophysical model function (GMF). The scientific value of the data is directly related to the quality of the
radiometric calibration.
There are currently two european C-band scatterometers operating, one on-board the ERS-2 spacecraft launched in
1995 and the other on-board METOP-A, launched in 2006. The similarity of the two scatterometers is an opportunity
to ensure the continuity of more than 15 years of global scatterometer measurements. To achieve the consistency of the
backscattering coefficients data sets, required for long-term climate studies, an accurate cross-calibration is vital. The
cross-calibration is made possible since the two spacecrafts operate simultaneously from 2006 up to now.
As the backscattering coefficients measured by the scatterometers depend on acquisition time, location on the ground
and on the geometry of the measurements (incidence and look angle), a direct comparison of measurements made by both
instruments is practically impossible.
In particular cases, models can be used to cope with measurement differences. On the rain forest, assumed to be
time-invariant, homogeneous and isotropic, the backscattering coefficient depends only on the incidence angle, and the
constant gamma model can be used to cope with the incidence angle effects. On some ice covered areas (e.g. Greenland
and Antarctica), assuming that the ice surface is isotropic, the ice line model can be used. It is a function of incidence
angle and ice age and depends on the location. On the ocean, which is inherently not stable in time, the CMOD5 GMF
is used. CMOD5 relates the observed backscatter to the geophysical parameters which are the wind speed and wind
direction. Using the last model, measurement biases can be assessed making simultaneous observations unnecessary.
Recent developments for the estimation of the altimeter bias for the Jason-1 and 2 satellites using the dedicated calibration site at Gavdos
Show abstract
The dedicated calibration site for satellite radar altimeters in Gavdos has been operational as of 2004. The small island of
Gavdos is located along a repeating ground track of Jason satellites (crossover point No 109 ascending and No. 18
descending pass and adjacent to Envisat), and where the altimeter and radiometer footprints do not experience significant
land intrusion. The purpose of such permanent Cal/Val facility is to calibrate the sea-surface height and ancillary
measurements made by the satellite as it passes overhead, by using observations from tide gauges, GPS, DORIS and
other sensors directly placed under the satellite ground tracks.
The successful launch of Jason-2 satellite (20 June, 2008) initiated its calibration-validation phase. This was achieved
having the two satellites flying with less than one minute difference and in the same orbit. Using the Gavdos calibration
facility the following have been determined: (1) the absolute altimeter bias of Jason-1 satellite for the cycles 209-259;
using GDR-C data; (2) the absolute altimeter bias of Jason-2 satellite for the cycles 2-28 using GDR-A data ; (3) the
inter- mission bias for the period July 2008 - January 2009.
The expansion of the Gavdos Cal/Val facilities with the deployment of a new site in the south of Crete and along pass
No. 109 is also presented in this work.
Infrared measurements of sea surface radiation: the MIRAMER campaign
Show abstract
The MIRAMER field campaign took place in the Mediterranean Sea during May 2008, both ground-based and on board
an oceanographic ship. Radiometric datasets along with the associated environmental measurements have been collected
in various environmental and observation conditions. It is dedicated to the validation of the sea surface optical properties
model implemented in the MATISSE-v2.0 code.
This analytical sea surface optical properties model in the infrared band is described. It allows the introduction of multiresolution
in the simulated field-of-view answering the need in computed images including any observational
configurations. It is valid for fully-developed seas, includes shadowing and hiding functions but not breaking and foam
nor multiple reflections.
First comparisons between simulations and measurements are presented in this paper.
Modeling the influence of water waves upon remote sensing imagery: the underwater radiance distribution and shape factors
Show abstract
This paper describes the results of modeling the water wave surface and underwater light field as influenced by water
waves using a Monte Carlo model (MCHSIM). Model and sensor data related to water column properties and benthic
properties that influence the light upwelled from below the water - as observed from a sensor looking from below or
above the water surface is presented. Synthetic image results using Monte Carlo techniques show the influence of water
waves upon subsurface shape factors and these factors can be used in shallow water remote sensing algorithms that are
based on underlying analytical models. The upwelling angular distribution of light is calculated from the model and
results shown for 490 nm. The upwelling and downwelling shape factors are shown from model runs which compare the
results with solar zenith angle for nadir viewing geometry, and for realistic water surface wave facets. It is clearly shown
that shape factors are strongly dependent upon not only viewing geometry and zenith angle of the sun, but also upon
water waves that can focus and defocus radiance entering a wind roughened water column and influence the shape
factors due to the scattering lobe effect. This paper presents results quantifying the magnitude of water effects upon the
upwelling and downwelling shape factors in a systematic and quantifiable manner at 490 nm and demonstrates the utility
of the model to assess the influence of water waves in a full 3-D Monte Carlo hyperspectral synthetic image cube model
that accounts for adjacency effects.
Imagery and In Situ Water Characterization
Resolution enhancement of hyperspectral data using multispectral imagery
Show abstract
Hyperspectral imagers tend to have lower spatial resolution than multispectral ones. This often results in a (sometimes
difficult) trade-off between spectral and spatial resolution. We have developed a technique, called CRISP, that combines
low-resolution hyperspectral data and high-resolution multispectral data to produce high quality, high-resolution
hyperspectral data. This technique shows good quantitative performance when applied to realistic applications such as
land cover estimation and anomaly detection. As a test of this technique, we have performed an experiment using
HyMap hyperspectral data and multispectral instruments over the coast waters of Oahu, Hawaii. The accuracy of the
CRISP sharpening approach when used for coastal applications such as depth mapping is assessed.
Accuracy and precisions of water quality parameters retrieved from particle swarm optimisation in a sub-tropical lake
Show abstract
Optical remote sensing has been used to map and monitor water quality parameters such as the concentrations of
hydrosols (chlorophyll and other pigments, total suspended material, and coloured dissolved organic matter). In the
inversion / optimisation approach a forward model is used to simulate the water reflectance spectra from a set of
parameters and the set that gives the closest match is selected as the solution. The accuracy of the hydrosol retrieval is
dependent on an efficient search of the solution space and the reliability of the similarity measure. In this paper the
Particle Swarm Optimisation (PSO) was used to search the solution space and seven similarity measures were trialled.
The accuracy and precision of this method depends on the inherent noise in the spectral bands of the sensor being
employed, as well as the radiometric corrections applied to images to calculate the subsurface reflectance. Using the
Hydrolight® radiative transfer model and typical hydrosol concentrations from Lake Wivenhoe, Australia, MERIS
reflectance spectra were simulated. The accuracy and precision of hydrosol concentrations derived from each similarity
measure were evaluated after errors associated with the air-water interface correction, atmospheric correction and the
IOP measurement were modelled and applied to the simulated reflectance spectra. The use of band specific empirically
estimated values for the anisotropy value in the forward model improved the accuracy of hydrosol retrieval. The results
of this study will be used to improve an algorithm for the remote sensing of water quality for freshwater impoundments.
Calibration and validation of a generic multisensor algorithm for mapping of turbidity in coastal waters
Show abstract
Turbidity, as defined in the standard ISO7027, is a parameter that is routinely measured in many national and regional
water quality monitoring programmes. The definition of turbidity according to ISO and as related to satellite data
products is discussed. While satellite data products are beginning to become available for the closely related parameter,
Total Suspended Matter (TSM), the direct estimation of turbidity as a satellite data product has not yet been addressed.
In situ measurements of TSM and of turbidity, obtained in the Southern North Sea (SNS), show high correlation
(correlation coefficient of 98.6%). A generic multisensor algorithm for TSM as function of reflectance has been
previously developed. The methodology is extended here to the estimation of turbidity from water-leaving reflectance. A
set of 49 seaborne measurements of reflectance in the spectral range 600-850nm and turbidity in the SNS are used to
calibrate the algorithm. The algorithm is also calibrated for the specific bands of MERIS. Validation of these models is
carried out using an independent set of seaborne measurements of turbidity and reflectance and shows low relative errors
in turbidity retrieval at 681nm (less than 35%). This wavelength is recommended, provided no significant fluorescence
affects this range.
Fusion of hyperspectral imagery and bathymetry information for inversion of bioptical models
Show abstract
Bioptical models are used jointly with hyperspectral imaging in inversion procedures for mapping of benthic habitats.
Several algorithms have been described in the literature to remove the effects of the water column and extract
information about the sea bottom that only take into consideration the measured hyperspectral image. However the
availability of LIDAR derived bathymetry information opens the possibility of using this information for improved
retrieval of the bottom properties. We present in this paper a study using simulated and hyperspectral imagery on the
improvement in benthic habitat mapping that can be achieved by fusing bathymetry and hyperspectral imagery.
Simulation results show that it is possible to obtain accurate bottom abundance estimates 5-10 meters beyond what can
be obtained with hyperspectral imaging alone in clear waters. With real data we demonstrate increase in accuracy with
respect to ground truth.
Role of surface winds in SAR signatures of oceanic internal waves in the northern South China Sea
Show abstract
It is well known that synthetic aperture radars (SARs) can image oceanic internal waves (OIWs). The signatures of
OIWs on SAR images result from the modulation of wind-generated surface waves by the surface currents associated
with the OIWs. The role of surface winds in SAR signatures of OIWs in the northern South China Sea is examined using
SAR images and BlendQscat wind data. A radar imaging model for simulating SAR signatures of OIWs is also used to
estimate the dependence of the radar signatures associated with OIWs on wind conditions. The results show that the
signatures of OIWs on SAR images in the northern South China Sea are highly dependent on the wind speed. The
temporal variations of the OIWs observed by SAR are closely related with the temporal variations of the wind speed in
the study area.
Poster Session
An adaptive lidar
Show abstract
Using the polarization characteristics of a target and its underlying surface one can change the target contrast range.
As the target one can use the compact and discrete structures with different characteristics to reflect electromagnetic
waves.
An important problem, solved by the adaptive polarization lidar, is to determine the availability and identification
of different targets based on their polarization characteristics against the background of underlying surface, which polarization
characteristics are unknown.
Another important problem of the adaptive polarization lidar is a search for the objects, which polarization characteristics
are unknown, against the background of underlying surface, which polarization characteristics are known. The
adaptive polarization lidar makes it possible to determine the presence of impurities in sea water.
The characteristics of the adaptive polarization lidar undergo variations, i.e., polarization characteristics of a sensing
signal and polarization characteristics of the receiver are varied depending on the problem to be solved. One of the
versions of construction of the adaptive polarization lidar is considered.
The increase of the contrast in the adaptive lidar has been demonstrated by the numerical experiment when sensing
hydrosols on the background of the Rayleigh scattering, caused by clear water.
The numerical experiment has also demonstrated the increase of the contrast in the adaptive lidar when sensing at
two wavelengths of dry haze and dense haze on the background of the Rayleigh scattering, caused by the clear atmosphere.
The most effective wavelength was chosen.
The study on dynamic changes of NPP in coastal ocean of China
Show abstract
Ocean primary productivity is the ability that the ocean primary producers convert inorganic matter into organic matter
through the assimilation. It is an important parameter used to estimate ocean biological resources and reflect the
characteristics and quality of the ocean ecological environment. With the development of ocean color remote sensing, it
has become possible by using the satellite remote sensing to monitor the ocean primary productivity. So, this study
selected China's coastal ocean (0°- 41°N, 105°- 130°E) as the main location, used NPP products of SeaWiFS estimated
from VGPM (Vertically Generalized Production Model), Eppley-VGPM and CbPM (Carbon-based Production Model)
from 1998-2007 to research the characteristics of space distribution and dynamic changes of NPP with time. The results
showed that: these models result have many same aspects and have many differences; the mean NPP of VGPM in all
ocean regions have two peaks, that of Eppley-VGPM and CbPM just have one peak; the NPP of China coastal ocean has
obviously seasonal and apatial variation. In time, the lowest value of NPP was in winter and the highest was in spring
and summer; in space, the Bohai and the Yellow Sea had relatively high NPP, relatively low value of the NPP was in
South China Sea.
Inherent error of Envisat ASAR level 2 algorithm and its correction
Show abstract
ESA's Envisat ASAR level 2 algorithm is used for retrieving ocean wave spectra (level 2 product) from synthetic
aperture radar (SAR) single look complex (SLC) data. Our studies show that in addition to the contribution of wind wave
part and swell part of the mixed waves, the cross spectra of mixed waves consist of an extra term. Just the extra term
leads to an inherent error of this algorithm which has not been considered yet. This paper presents the error analysis of
ESA's algorithm for ocean wave spectra retrieval in different significant wave height (SWH), wave length and wave
component conditions based on simulation technique. To correct the inherent error of ESA's algorithm, a new method
named unconstrained cross spectra method for directional ocean wave spectra retrieval from SAR SLC imagery is also
presented. Case studies show that the new method can avoid the inherent error of ESA's algorithm very well.
The low water-leaving radiances phenomena around the Yangtze River Estuary
Show abstract
Based on the in-situ data and ocean color remote sensing data of SeaWiFS, we found there was a black water region with
the normalized water-leaving radiances less than 0.5 mW/(cm2•μm•sr) at the visible light wavelength. Yangtze River
Estuary locates in the East China Sea shelf with shallow water. Affected by the tide mixing and the runoff of the Yangtze
River and Qiantang River, the turbidity is very high. Generally, the water-leaving radiance is high in the turbid water
because of the large particle scattering. The reason of the occurrence of this black water was analyzed by the inherent
optical properties and the ocean color components. The results showed that black water was caused by the relative low
values of the suspended particle matter concentration and the back scattering ratio.
Development of a new algorithm of suspended sediment concentration from satellite remote sensing data in the East China Sea
Show abstract
Suspended sediment is an important parameter of water quality and a main factor to affect the lifetime of port use,
which needs to be monitored on the spatial distribution and temporal changes. It also dominates the optical properties in
the coastal ocean and makes it difficult to retrieve chlorophyll concentration and other water constituents from satellite
remote sensing data. Many algorithms were developed to retrieve suspended sediment concentration (SSC) from satellite
remote sensing data and most of them were tested to be used for the region of the East China Sea. The results show that
relative errors are too large to be more than 100% under high concentration of sediments. This region, especially in the
Yangtze estuary and Hangzhou Bay, is famous for large area distribution of high concentration of suspended sediment, as
high as more than 1000 mg/l. A new algorithm is developed, based on a large amount of in-situ measurements of four big
cruises, each of these cruises employ two big ships to take about two months to measure about 200 stations. First, the
relationship between the water-leaving radiance at different wavelengths and SSC was analyzed and the results show that
the radiance at green bands is sensible to SSC at low concentration and almost saturated at high concentration, while the
radiance at red bands has a good relationship with SSC at high concentration, meanwhile the radiance at near-infrared
bands has also a big value under high SSC. Then the accuracy of the algorithm is evaluated and shows that the algorithm
has a nice performance both at low and high SSC. Finally, the algorithm is used to obtain SSC from SeaWiFS and
MODIS data and the distribution of SSC show that the algorithm is suitable for retrieving SSC from satellite remote
sensing data in the East China Sea.
Investigation of sea roughness with complex of optical devices
Show abstract
This paper is concerned with the complex of optical devices for recording of sea waves characteristics in wide range of
wavelength from centimeters to hundreds meter.
The energy spectra of short waves are obtained in real time by spectral analysis of sea surface image with spectral
analyzer operating under no coherent light. The spectral-kinematics characteristics of long energy waves are determined
from optical RTI images (range-time-intensity images) constructed from optical profiles of sea surface.
A model of imaging of the sea surface in diffuse sky light is developed using twoscale approach of sea roughness that
permits to receive new expression for spectra of sea surface wave image. The principles of retrieval of spectralkinematics
characteristics of surface waves from RTI images are developed and method for formation of RTI images
permitted to remove influence of ships tossing is proposed.
The preliminary model of sea wave elevation spectra for wavelength from centimeters to meter derived from spectra of
sea surface images and its changing in wind front is presented. The appearance of group structure of long surface waves
is registered on optical RTI images of sea surface.
The complex of optical devices may be used from shore or ship for monitoring of sea surface roughness in real time.
China Imaging Altimeter and its possible oceanic applications
Show abstract
The China Imaging ALTimeter (CIALT) is designed by the Center for Space Science and Applied Research of the
Chinese Academy of Sciences. It is a new generation of altimeter which integrates the synthetic aperture technique and
the interferometric technique into traditional altimeters. It operates in Ku-band with an incidence angle of less than 5°.
These new characteristics bring us the expectative applications. The possible oceanic applications in marine geoid, ocean
currents, mesoscale eddies, ocean surface winds, waves, and tides, etc. are presented.
Satellite-based real aperture radar image spectrum simulation with Wen's wave spectrum
Show abstract
Some missions have been carried out to measure wave directional spectrum based on airborne real
aperture radar in a low incidence. For this study, the authors simulate the satellite-based real aperture
radar image spectrum to validate the radar performance of measuring the directional wave spectrum
based on the same principal as airborne one. In the processes of the simulation, the authors don't take
into account the rotation of antenna and the disturbing of the noise in order that the simulation can
exclude other factors to purely verify the measuring theory feasibility in essence. The authors use
Wen's spectrum as the input spectrum of the simulation, which is a kind of wind-generated wave
spectrum that can better describe the state of developing wave and the statuses of the Chinese sea fields.
Following that, the simulated sea surface, backscattered radar signal, modulation spectrum and the one
dimension wave spectrum (two dimension one can be obtained by synthesizing every directional one
dimension spectrum) are obtained, which is compared with the input spectrum. To have a
comprehensive realization to the performance of the radar, different cases including different
developing degree, wind speed and angle between dominant waves propagation direction and radar
look direction are considered. Presented results show that Satellite-based real aperture radar can mostly
measure the wave spectrum, but the capacity is limited on the cases of low wind speed, developing
waves and the big angles.
Analysis of simulated and actual airborne remote sensing imagery for characterization of surface water wave spectra
Show abstract
Simulated and airborne imagery demonstrate the ability to see manmade and natural objects below the water wave
surface. Traditional photogrammetric imagery and airborne digital imagery both suffer from a loss in image clarity due
to a number of factors, including the forward motion of the airborne platform. Blurring due to this effect can be
calculated and an opto-mechanical system has been designed in order to help remove this effect. Forward motion blur
can be shown to occur on the order of a several centimeters and calculation results are presented. The system is
described and imagery is shown to demonstrate image blurring. Preliminary results obtained from an improved Monte
Carlo model is also used to show expected results and to begin developing image correction methods in order to remove
the blur due to water wave influences. Limitations to the hardware method suggest that the opto-mechanical system
designed may lead to additional blur due to nonuniform focal plane focusing issues. The techniques have unique
opportunities to help improve hyperspectral pushbroom sensors in addition to large frame mapping cameras that are in
use today or being developed for future use.
Intercorrelation between natural microwave radiation of the ocean-atmosphere system and its boundary heat and dynamic interaction
Show abstract
We analyze here the intercorrelation between natural microwave radiation of the ocean-atmosphere system and its
boundary heat and dynamic interaction and describe some approaches to an analysis of heat and dynamic processes in the
ocean-atmosphere interface with satellite passive radiometric observations at microwaves. The feasibility of determining
synoptic, seasonal and year-to-year variations of sensible, latent heat and momentum fluxes to a useful accuracy using
the DMSP SSM/I data directly from the measured brightness temperatures is examined. The main results have been
obtained by combining the data of the vessel experiments NEWFOUEX-88, ATLANTEX-90 and the data of microwave
radiometric measurements from the meteorological satellites of the DMSP series. Especial part of our study is the
elaboration of technologies for diagnosis of tropical hurricanes beginning in the oceans with the remote sensing methods.