In this research, we focus on vessel detection using the satellite imagery of day/night band (DNB) on Suomi NPP in order to monitor the change of vessel activity on the region of South China Sea. In this paper, we consider the relation between the temporal change of vessel activities and the events on maritime environment based on the vessel traffic density estimation using DNB. DNB is a moderate resolution (350-700m) satellite imagery but can detect the fishing light of fishery boats in night time for every day. The advantage of DNB is the continuous monitoring on wide area compared to another vessel detection and locating system. However, DNB gave strong influence of cloud and lunar refection. Therefore, we additionally used Brightness Temperature at 3.7μm(BT3.7) for cloud information. In our previous research, we construct an empirical vessel detection model that based on the DNB contrast and the estimation of cloud condition using BT3.7. Moreover, we proposed a vessel traffic density estimation method based on empirical model. In this paper, we construct the time temporal density estimation map on South China Sea and East China Sea in order to extract the knowledge from vessel activities change.
The detection limit of DNB was proposed as a function of the brightness temperature (BT) at 3.7 μm, where the transmittance of cloud could be observed as a change of surface temperature. The shortwave infrared band exhibited a wide distribution in BT more than the thermal infrared band for the same level of DNB radiance. The lights from surface were identified even under the full Moon condition with the proposed method, where clouds were reflecting the lunar lights. A different distribution of clouds for day to day and a change of the Moon phase with its elevation make this problem more complicated. But the approach of contrast based evaluation of surface lights and lunar reflected lights could be one solution to distinguish the lights from the surface. Currently, a validation is necessary in the future to confirm this algorithm and to validate the detected pixels to be fishing boats with the stable light sources. The time series data of fishing boats could be studied to analyze the region of fishing area relative to the distribution of sea surface temperature and/or chlorophyll-a.
The phytoplankton distribution in the East China Sea (ECS) was analyzed by the statistics of the discharge and the
sediment load of the Yangtze River at the Datong station from 2000 to 2005 and satellite images of chlorophyll-a
concentration which were observed by Sea-viewing Wide Field-of-view Sensor (SeaWiFS) from 2000 to 2005. This
study suggests that phytoplankton distribution in the ECS in the spring and fall season could be determined by the
amount of discharge, sediment load, and sediment concentration from the Yangtze River. The standing stocks of
chlorophyll-a along the water column could be determined by the nutrient concentrations through the winter season.
Also, this study suggests that the sediment load may have two functions to increase the primary productivity by an
increase of silicate concentration and to decrease the primary productivity by an increase of diffused attenuation
coefficient. However, the phytoplankton distribution in the summer season could not be simply determined from the
discharge, sediment load, and sediment concentration from the Yangtze River. The associated or inherent parameters
like diffused attenuation coefficient or primary productivity may have a significant contribution to the spatial distribution
of phytoplankton in the summer.
Ocean color monitoring on the coastal water is still under study because of an incomplete atmospheric correction
over the turbid water like over the coastal water along the China main land. Currently available sensors for science as
MODIS on Terra or Aqua will terminate their service in the near future and the NPOESS Preparatory Project (NPP) will
be the next satellite to support the satellite oceanography on the coastal water. The Tokyo University of Information
Sciences (TUIS) has updated the MODIS receiving system to capture and ingest the Visible/Infrared Imager/Radiometer
Suite (VIIRS) data from NPP, which will be launched in 2008. Data processing software from the Direct Readout
Laboratory (DRL), such as the Real-time Software Telemetry Processing (RT-STPS), Simulcast, and DB algorithms,
will be core programs in our system. VIIRS has seven bands in VIS&NIR, which are for ocean color research. The
spatial resolution is 0.742×0.259 meters at nadir. While the MODIS spatial resolution of the nine ocean color bands is
1000m. The higher spatial resolution MODIS data (250 meters) is used to illustrate the advantage of the higher spatial
resolution remote sensing data, such as data from VIIRS. In this study, we propose to combine the higher spatial
resolution data with the traditional products of chlorophyll-a and sea surface temperature in the low resolution so as to
extract further information on the coastal ocean.
The multi-parametric data observed by the Synthetic Aperture Radar (SAR) and the Moderate Image Scanning
Radiometer (MODIS) were applied to analyze the water distribution in the Philippine Archipelago to build a new radar
imaging model. The SAR provides information on the surface structure of the water affected by various phenomena
such as currents, internal waves, swells, surface winds, rain falls, natural films, and so on. One difficult parameter
among them is the natural film, which exhibits a damping effect to the surface roughness from breaking waves to
capillary ones. The chlorophyll-a concentration observed by satellite sensors such as MODIS provide estimates of the
standing stock of phytoplankton, which is considered as the parameter estimating the standing stock of zooplankton.
The standing stocks of phytoplankton and zooplankton could be a proportional parameter to the amount of the natural
film. In this study, a frequency dependent multi-parametric equation was proposed to rebuild the surface roughness with
various parameters in the spectrum domain. Possible validation study was conducted with the relationship between the
sum of power spectrum for certain frequency range with chlorophyll-a concentration on the Mindanao Sea and the
Surigao Strait.
The Global Imager (GLI) on Advanced Earth Observing Satellite-II (ADEOS-II) launched on 14 December 2002 is an optical sensor to observe reflected solar radiation and infrared radiation. GLI has 36 channels from ultraviolet region (380nm) to thermal infrared (12micron). GLI data is used for understanding the global circulation of carbon, monitoring cloud, snow, ice, and sea surface temperature. NASDA carried out initial checkout to confirm GLI basic function until April 2003. Currently GLI calibration team that consists of sensor development division, ground system integration division, and science application group analyses calibration and validation to release L1 data at the end of this year. This report describes calibration and instrument status of GLI.
Global Imager (GLI) is the visible to infrared imager aboard ADEOS-II satellite with 30 and 6 channels for 1 km and 250m resolutions, respectively. The sensor was successfully captured the first image on January 25, 2003. Sea surface temperature (SST) will be retrieved in combination with simultaneous SST observation by low-resolution microwave sensor, AMSR-E. Distribution of chlorophyll and other constituents will be obtained from ocean color channels. Frequent observations with 250 m visible channels will be also available, and combination with 1 km ocean color and SST will be useful for coastal applications. Early scientific results of GLI ocean group will be presented in this presentation.
The Advanced Earth Observing Satellite-II (ADEOS-II) was launched on 14 December 2002, and its functions were checked until 2003 spring. The Global Imager (GLI) on board ADEOS-II has 36 channels (thirty 1-km resolution, six 250-m resolution) from ultraviolet to thermal infrared to facilitate understanding the global environmental changes in oceans, land and clouds with high accuracy. Ocean algorithms (e.g., ocean atmospheric correction and sea-surface temperature) need highly accurate sensor characterization coefficients because they retrieve sea-surface upward radiance precisely from the top of the atmosphere. The NASDA GLI calibration team includes members of sensor development, ground system integration, and science application groups. The team started investigating GLI characteristics and radio- and geo-correction processes in the initial verification period. In this paper, we will describe the initial results, radiometric accuracy, 12- or 48-detector dependency, scan-mirror surface, incident-angle dependency, and dynamic range related to oceanographic applications.
The GLI was launched on board the ADEOS-II on December 14, 2002. For the early phase evaluations of the observation radiances, the GLI calibration team carried out vicarious calibrations by using MOBY measurements. To achieve the calibrations, we used two methods, which utilize two near-infrared channels and the measurement of the aerosol optical thickness, to predict the aerosol optical properties. Applying these methods, we derived early GLI vicarious calibration factors for ocean-color channels.
A primary productivity model for the turbid water is proposed using the remote sensing data. In previous studies, we proposed a time and depth resolved primary productivity model for a global scale, but results indicated significant errors on the East China Sea. A euphotic zone estimated in this model was based on a chlorophyll α concentration in the surface, which made errors on the turbid water. A photosynthetically available radiation and chlorophyll α concentration along the water column are defined as a function of the diffused attenuation coefficient and chlorophyll α concentration in the surface.
To deliver high quality data sets to the user community, space sensors have to be calibrated with high accuracy. Besides pre-launch and on-board calibration, there exists the possibility to inter-compare the sensor data using well-characterized ground sites. To cover different radiometric signal levels, ground sites with high and low spectral reflectance (and surface temperatures) were chosen to allow not only an absolute signal comparison, but also an estimation of the linearity of the sensor signal. This why one ground site is located at in the dark ocean (East china sea), and the other is a fresh snow site in the polar region (alternating: Arctic and Antarctic cal sites). These polar sites have the advantage to compare sensors from different sun-synchronous orbit satellites platforms on the same day, i.e. semi-simultaneous measurements can be performed.
The dark ocean site will be located near Ishigaki Island (Japan) at 24°37'N and 123°27'E using optical buoy data and frequent in-situ measurements. The snow target sites are in the Antarctic and Arctic, where measurements will be carried out in the polar autumn and spring near Syowa Station (East Ongul Island, Lützow-Holm Bay, East Antarctica; 69°S and 39°35'E) and near Barrow (Alaska, USA; 71°16'N, 156°50'W).
In the scope of the project the ground sites will be characterized (depending on logistical and weather conditions), to allow an estimation of the TOA signal, which will be calculated using either developed codes or generated products. After systematic (space sensor and ground-truth) data acquisition and analysis, a comparison between these space sensors will be provided to assess long-term variations and trends in the calibration.
This paper describes the ongoing preparation (e.g., data selection, ground truth measurements and algorithm development) for a systematic inter-sensor comparison of the GLI and MERIS/AATSR sensors, which are onboard of ADEOS-2 and ENVISAT satellites.
The whiskbroom scanner Global Imager (GLI) will be launched on Advanced Earth Observation Satelite 2 (ADEOS-2). It will provide remotely sensed data from the Earth surface from the visible to the thermal infrared. Since the Earth observation data require a careful calibration, different on-board calibration tools have been integrated in the GLI hardware design. For the VIS-SWIR spectral range a special calibration device allows solar and lamp calibration. In this paper a calibration strategy is presented to achieve a high calibration accuracy of the remotely sensed data by means of solar calibration. Therefore the theoretical background, the performed hardware characterization and applied external data basis are presented. Further on it is shown how a stray light simulation analysis using a non- sequential ray-tracing tool will be used to increase the reliability of the solar calibration.
We proposed a photosynthetically available radiation dependent primary productivity model. A vertical distribution of PAR is defined as an empirical equation of the chlorophyll-a concentration in the surface, which is observed by an ocean color sensor. A vertical distribution of chlorophyll-a concentration is defined as an empirical equation of the vertical distribution of PAR and the chlorophyll-a concentration in the surface. A vertical distribution of primary productivity is defined as an empirical equation of the vertical distribution of PAR and the temperature. We retrieved those empirical equations from the previous in-situ measurement. A primary productivity of the water column is given as an integration of those parameters along the water column. Results of primary productivity model, applied on a series of SeaWiFS data, showed a good agreement with in-situ observation.
Small size phytoplankton are dominated in the western and central equatorial Pacific. Our study of HPLC measurements, size fractions of chlorophyll (alpha) and flow cytometric measurements indicate that phytoplankton communities in the equatorial Pacific are dominated by prokaryotic picophytoplankton with Prochlorococcus and Synechococcus, and small size autotrophic eukaryotes. Phytoplankton populations and the distribution were showed to differ from oligotrophic warm water region of the western equatorial Pacific and mesotrophic upwelling region of the central equatorial Pacific. In the oligotrophic region, phytoplankton distribution forms maximum layer around the nitracline. Prochlorococcus is most abundant in there. In the mesotrophic region, chlorophyll maximum layer is not found clearly. The population of autotrophic eukaryotes represented as prymnesiophytes were increased in there. Specific spectral absorption coefficients of phytoplankton [(alpha) *ph((lambda) )] were measured throughout the euphotic zone in the two different regions. The (alpha) *ph((lambda) ) were also reconstructed from HPLC results as the total of specific spectral absorption coefficients of chlorophyll (alpha) [(alpha) *chla((lambda) )], chlorophyll b [(alpha) *chlb((lambda) )], chlorophyll c [(alpha) *chlc((lambda) )], photosynthetically active carotenoids [(alpha) *psc((lambda) )] and photoprotective carotenoids [(alpha) *ppc((lambda) )]. Reconstructed (alpha) *ph((lambda) ) were compared with measured (alpha) *ph((lambda) ). Reconstructed (alpha) *ph((lambda) ) were overestimated at the field of (alpha) *psc((lambda) ), especially in the mesotrophic region. The (alpha) *psc((lambda) ) were considered as high contribution of prymnesiophytes. It was assumed that the package effect of prymnesiophytes was a cause of the overestimate of reconstructed (alpha) *ph((lambda) ).
Measurements of 'Photosynthesis versus Irradiance' were conducted at 9 stations along the Equator from 145 degrees East to 170 degrees West in December 1999. Samples were obtained at about from the surface and chlorophyll maximum layer. The samples were inoculated with C-13 and incubated for 3 hours in a temperature controlled linear incubator which has 8 light levels. The P-I equation of Platt et al. is employed to calculate the initial slope, Pmax and the saturation parameters. It was La-Nina condition in this period and the influence of 'cold-tongue' came over around 160 degree East. Pmax varied from 1.7 to 4.7 (gC/gChl/h) on the surface. The minimum value of Pmax on the surface was observed at 160 degree East. The value increased gradually to the east and also to the west. On the other hand, the initial slope does not change so much and we cannot see such an east-west variability as Pmax. As it has been pointed out in previous studies, Pmax and the saturation parameter tend to decrees with depth and the initial slope tends to be lower near the surface.
Through the bio-optical measurement over the equatorial warm water pool, we could discuss the vertical structure of the chlorophyll maximum. The chlorophyll-a from the surface to the top of the chlorophyll maximum layer was expressed as the inverse function of photosynthetically available radiance (EdPAR). The chlorophyll-a from the bottom of chlorophyll maximum layer to 150 m was expressed as logarithm function of EdPAR. As we could observe the different current streams within the surface mixed layer by the ship-mounted ADCP, we could make a new hypothesis on the generation of chlorophyll maximum layer in the warm water pool. As the top portion of the chlorophyll maximum layer is in the east-north-east current and the nitrate in this layer is depleted, it is supposed the chlorophyll maximum to be maintained by the reproduction. As the deeper portion of the chlorophyll maximum layer was on the top of the north-west current and it was just above the nitracline, it is supposed the chlorophyll maximum to be maintained by the new production.
In applying an ocean lidar equation, a reflectance and a refractivity of a random surface of the water is the most difficult parameter for an actual ocean lidar observation. A flight test of an airborne ocean lidar and a surface test of a shipboard ocean lidar showed variations of intensity of light scattered from a depth of the water. We built a multiparameteric shipboard ocean lidar to examine a hypothesis that variations of light scattered or fluorescence from the depth could be given as a function of light reflected at the surface of the water. As a result, we have confirmed that light scattered or fluorescence from the depth was independently given from variations of light reflected at the surface of the water on the current lidar system.
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