Xianqiang He

State Oceanic Administration, Tsingtao, Shandong Sheng, China

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Publications (70)44.18 Total impact

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    ABSTRACT: The Penghu Channel is the main channel connecting the East and South China Seas, two of the largest marginal seas in the world. Located in the southeast of Taiwan Strait, the Penghu Channel is usually covered by the high salinity water from the South China Sea and the Kuroshio. However, we observed abnormal low-salinity water in the Penghu Channel during a cruise through the southern Taiwan Strait and northern South China Sea in August 2008. We argue that the normalized alkalinity is a good indicator for the identification of a river plume as it is not affected by rainwater. Using satellite-derived water transparency and chlorophyll images and field-measured alkalinity, the source of this low salinity water was found to be the intrusion of the Pearl River plume. A significant phytoplankton bloom across the entire Taiwan Strait occurred with the intrusion event. The intrusion was not a unique event, as we also found a strong jet-shaped Pearl River plume intruding into the Penghu Channel in the summer of 2009 from cloud-free satellite-derived images. Time series satellite data reveal that the Pearl River plume intrudes into the Penghu Channel in the summer of most years. Multiple data analysis and modeling simulation indicate that a large river discharge and strong southwesterly winds on the shelf may be responsible for the significant intrusion of the Pearl River plume into the Penghu Channel in summer. As the Pearl River plume has a high nutrient and dissolved inorganic carbon content, combined with the strong northward flows through the Penghu Channel, such intrusions may contribute to the nutrient dynamics and carbon budget of the East and northern South China Seas.
    Journal of Sea Research. 01/2015; 95:1-15.
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    ABSTRACT: The discharge of nitrate and phosphate from Changjiang (Yangtze River) has increased in recent decades. Eutrophication off the mouth of Changjiang has subsequently become a serious problem, as evidenced by the hypoxia area reaching 12,000 km2. This study demonstrates that in the wider East China Sea (ECS) the nitrate and phosphate concentrations in the Kuroshio Intermediate Water (KIW) have also increased, but the dissolved oxygen (DO) concentration has decreased since as early as 1982, most likely owning to reduced ventilation in the North Pacific Intermediate Water (NPIW). Conversely, the Kuroshio Tropical Water (KTW) has decreased in the nitrate and phosphate concentrations yet increased in DO concentration. As KIW contributes substantially to the upwelling, the nitrate and phosphate concentrations in the bottom water on the outer shelf of the ECS appear to have increased as well, but the DO has decreased. Given that the nutrient inputs from both the land and the Kuroshio Current have increased, yet the input of DO from the Kuroshio has decreased, more severe eutrophication and hypoxia may occur in the entire ECS. Similar processes may also affect other shelves that come into contact with NPIW.
    Estuarine Coastal and Shelf Science 08/2014; · 2.32 Impact Factor
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    ABSTRACT: Using an improved satellite-derived salinity algorithm in the East China Sea (ECS), we presented and examined a general view on summertime Changjiang River plume variation during 1998–2010. Three types of plume shapes were identified: 1) the commonly known northeastward transportation, 2) a case in which most of the plume water crossed the Cheju Strait into the Tsushima-Korea Straits with only a small fraction staying on the shelf of the ECS, and 3) a rare case in which the plume front moved southeastward. Satellite time-series data suggested that, during the peak river discharge time in July with favorable southwest monsoon, the plume area was highly correlated with the river discharge of the same month. Interestingly, the plume area in August was also dominated by the discharge in July. In August, as the direct effect of freshwater discharge weakening, the plume area also became positively correlated with wind speed in the 45o and 60odirection, suggesting that the plume extension was more influenced by the southwesterly wind during periods of smaller discharge. Furthermore, a few special cases with unique plume extensions were found under extreme weather conditions. Finally, we found no significant long-term trend of plume area change over 1998–2010 in summertime and concluded that the interannual variation was probably regulated by natural variation rather than anthropogenic effects, such as construction of the Three Gorges Dam. This study will have implications for biogeochemical and modeling studies in large river plume areas.
    Journal of Geophysical Research: Oceans 08/2014; · 3.44 Impact Factor
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    ABSTRACT: Using satellite-derived water transparency (alias Secchi depth) images, we found clear signals of terrestrial material transport to the southern Okinawa Trough triggered by the Typhoon Morakot in August 2009. Three sources were identified: one is from the eastern coast of Taiwan, another is from the western coast of Taiwan, and the other is from the coast of mainland China. Carried by northward flows, typhoon-triggered terrestrial materials from both sides of Taiwan's coasts were transported to the region northeast of Taiwan. Moreover, the terrestrial material from the coast of mainland China could cross the Taiwan Strait and be further transported to the region northeast of Taiwan. These typhoon-induced terrestrial materials off northeastern Taiwan could then be transported to the southern Okinawa Trough along the western edge of the Kuroshio. In addition to the particulate terrestrial material transported, nutrients might also be transported to the Kuroshio main stream. A significant phytoplankton bloom was observed along the Kuroshio path for about 300km off northeast of Taiwan. Our results indicate that episodic cyclone-driven terrestrial material transport could be another source of mud in the southern Okinawa Trough.
    Journal of Geophysical Research: Oceans 07/2014; · 3.44 Impact Factor
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    ABSTRACT: Ocean colour remote sensing has supported research on subjects ranging from marine ecosystems to climate change for almost 35 years. However, as the framework for ocean colour remote sensing is based on the radiation intensity at the top-of-atmosphere (TOA), the polarisation of the radiation, which contains additional information on atmospheric and water optical properties, has largely been neglected. In this study, we propose a new simple concept to ocean colour remote sensing that uses parallel polarisation radiance (PPR) instead of the traditional radiation intensity. We use vector radiative transfer simulation and polarimetric satellite sensing data to demonstrate that using PPR has two significant advantages in that it effectively diminishes the sun glint contamination and enhances the ocean colour signal at the TOA. This concept may open new doors for ocean colour remote sensing. We suggest that the next generation of ocean colour sensors should measure PPR to enhance observational capability.
    Scientific Reports 01/2014; 4:3748. · 5.08 Impact Factor
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    ABSTRACT: Climate change has become one of the hotspots of global attention in recent progress of globalization and industrialization. The mainstream opinion presented by Intergovernmental Panel on Climate Change (IPCC) regards that the global warming was caused mainly by greenhouse gases generated by human activities, such as anthropogenic CO2, which also resulting in the high-frequent happening of abnormal climate events. Satellite remote sensing is an efficient and economic method for CO2 flux observation. In this paper, we describe an Information System of Ocean Satellite Monitoring for Ari-sea CO2 Flux (IssCO2) which developed by the Second Institute of Oceanography, China. The IssCO2can achieve the whole procedure automatically from the satellite remote data receiving to products distribution, including the data acquirement and satellite image process, products generation, etc. The IssCO2 can process various types of in situ data, satellite data and model data, and validate the final satellite-derived CO2 flux products by in situ data; it can provide a real-time browsing and download of remote sensing products on the web based on the Geo-information System (GIS) technologies. The IssCO2 can meet the concurrent queries of different levels of users, and the query results can be visual displayed and analyzed on the client.
    Proc SPIE 10/2013;
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    ABSTRACT: Two episodic phytoplankton bloom events were identified in the southeastern and southwestern Bay of Bengal in January 1998 and December 2005, respectively, from SeaWiFS-derived chlorophyll-a concentration data collected between September 1997 and December 2010. Possible causes were examined using time series datasets of satellite-derived sea surface height anomalies, sea surface temperature, wind stress and Ekman pumping velocity data. It was found that strong cyclonic eddies with long residence time transported cold, nutrient-rich water from the subsurface layer to the euphotic zone, and were responsible for sustaining the continuous growth of phytoplankton that led to the two aforementioned phytoplankton blooms. Moreover, regarding the event in December 2005, three tropical cyclones passed through the region of the phytoplankton bloom and could have been additional factors that enhanced the bloom. Regarding the event in January 1998, transportation from the adjacent Andaman Sea by the geostrophic current and an anomalous zonal easterly wind contributed to the phytoplankton bloom in the southeastern Bay of Bengal. In addition, both blooms occurred during Indian Ocean Dipole (IOD) years. The absence of the second downwelling Kelvin waves in positive IOD year of 1997–1998 favouring the long residence of the strong cyclonic eddy in the eastern bay, and the strong wind-induced mixing in negative IOD year of 2005 might contribute to enhancing productivity.
    Deep Sea Research Part I Oceanographic Research Papers 08/2013; 73:17–30. · 2.82 Impact Factor
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    ABSTRACT: Total suspended particulate matter (TSM) in coastal waters is often characterized by high concentration and significant diurnal dynamics. Insufficient spatial and temporal resolution limits both cruise sampling and polar-orbiting satellite remote sensing in the mapping of TSM diurnal dynamics in coastal regions. However, the in-orbit operation of the world's first geostationary satellite ocean color sensor, GOCI, provides hourly observations of the covered area. In this study, we proposed a practical atmospheric correction algorithm for GOCI data in turbid waters. The validation results showed that the GOCI-retrieved normalized water-leaving radiances matched the in situ values well in both quantity and spectral shapes. We also developed a regional empirical TSM algorithm for GOCI data that is applicable in extremely turbid waters. Based on these atmospheric correction and regional TSM algorithms, we generated hourly TSM maps from GOCI Level-1B data. The diurnal variations derived by GOCI were a good match to the buoy data. The hourly GOCI observations revealed that various regions and tidal phases had different diurnal variation magnitudes, with a maximum of up to 5000 mg/l in central Hangzhou Bay. Strong wind events, such as typhoons, can significantly increase TSM in the bay; however, both the GOCI observations and buoy measurements indicated that this increase was episodic, had a short duration, and returned to normal within a day after the passage of a typhoon. Our results suggest that GOCI can successfully map the diurnal dynamics of TSM in turbid coastal waters. Moreover, the significant diurnal dynamics revealed in the hourly GOCI observations implied that caution should be taken in mapping TSM in coastal waters using cruise sampling and conventional polar-orbiting satellite data, as the temporal resolution is insufficient for catching diurnal variations.
    Remote Sensing of Environment 06/2013; 133:225–239. · 5.10 Impact Factor
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    ABSTRACT: River plumes are the regions where the most intense river-sea-land interaction occurs, and they are characterized by complex material transport and biogeochemical processes. However, due to their highly dynamic nature, global river plume areas have not yet been determined for use in synthetic studies of global oceanography. Based on global climatological monthly averaged salinity data from the NOAA World Ocean Atlas 2009 (WOA09), and monthly averaged salinity contour maps of the East and South China Seas from the Chinese Marine Atlas, we extract the monthly plume areas of major global rivers using a geographic information system (GIS) technique. Only areas with salinities that are three salinity units lower than the average salinity in each ocean are counted. This conservative estimate shows that the minimum and maximum monthly values of the total plume area of the world’s 19 largest rivers are 1.72×106 km2 in May and 5.38×106 km2 in August. The annual mean area of these river plumes (3.72×106 km2) takes up approximately 14.2% of the total continental shelves areaworldwide (26.15×106 km2). This paper also presents river plume areas for different oceans and latitude zones, and analyzes seasonal variations of the plume areas and their relationships with river discharge. These statistics describing the major global river plume areas can now provide the basic data for the various flux calculations in the marginal seas, and therefore will be of useful for many oceanographic studies.
    Acta Oceanologica Sinica -English Edition- 01/2013; 32(1):79-88. · 0.58 Impact Factor
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    ABSTRACT: [1] Defining highly variable freshwater plume area from space is important for characterizing the dynamics of biogeochemical properties and understanding the effects of climate change and human activities on plume-related processes. The absorption coefficient of colored dissolved organic matter (aCDOM) from satellite ocean color data can be used to estimate the salinity and thus the plume area in coastal oceans if a robust conservative salinity and aCDOM relationship and an accurate satellite aCDOM algorithm can be established. In this paper, tight relationships between surface water salinity and in situ aCDOM were found during several cruises covering all seasons and the full salinity range in the East China Sea. Thus, a salinity inversion model from aCDOM was developed and validated with an independent data set, in which 73.6% of the data were within the absolute salinity error of ±1 and 87.1% were within ±1.5. Factors influencing the conservative behavior of colored dissolved organic matter are analyzed, with a particular focus on the effect of the phytoplankton-induced autochthonous colored dissolved organic matter. In addition, several satellite aCDOM algorithms were compared and validated with our in situ data. Monthly satellite-derived salinity images were mapped in August from 2008 to 2010 and showed the significant interannual variability in the plume coverage. This study demonstrated that the salinity derived from satellite-derived aCDOM can provide a reliable and good synoptic view of the plume area, and help with biogeochemical studies, in particular, those properties related to the interannual variability of plume coverage, although the development of a localized satellite algorithm of aCDOM is still desirable.
    Journal of Geophysical Research: Oceans 01/2013; 118(1):227-243. · 3.44 Impact Factor
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    ABSTRACT: A total of 12 years (2000-2011) of sea surface wind data from QuikSCAT and ASCAT are employed to examine the seasonal and interannual variability over the China Seas and its adjacent ocean. The wind speed and direction, strong wind frequency, monsoon onset and transition time are revealed by statistic analysis. The result shows that (1) the wind speed is highest in winter and lowest in summer in the study area. The Southeastern Vietnam, Luzon Strait, Taiwan Strait and the eastern ocean of Japan are the regions with the higher wind speed throughout the year, especially more than 12 m/s in winter. (2) The monsoon prevails in the China Seas, southwesterly in summer and northeasterly in winter, while southeast wind also occurs all the seasons except winter. The northwest wind only occurs in the north of 27°N in winter. (3)The strong wind more than 10.8 m/s exceeds 140 days per year in the Taiwan Strait while only 30 days in the Bohai Sea and Yellow Sea. In addition, the Luzon Strait can reach 120 days with strong wind larger than 10.8 m/s, ranking the second after the Taiwan Strait. (4) The time of monsoon onset changes from year to year. Generally, the southwest wind in the low latitudes begins in May and ends in September or October, then turns to northwest wind completely which almost have no transition time. For the mid-latitudes zone, the southwest wind begins in June and ends in August. May and September are the transition time. Then the northeast wind begins to prevail. (5) The trend of sea surface wind speed in the study area is increasing from 2000 to 2011, except the Southeastern Vietnam. The annual mean wind speed is lowest in 2002 and 2010 during the period of. 2000-2011
    Proc SPIE 09/2012;
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    ABSTRACT: The East China Sea (ECS) is the 11th largest marginal seas around the world. ECS has widely continental shelf, and has relatively high concentration of suspended particulate matter (TSM) affected by the terrestrial material from the large rivers, including the Changjiang River, and also affected by the resuspension in the winter. Recently, several regional algorithms for the TSM retrieval in the ECS have been proposed, such as the algorithms developed by Zhang et al. (2010) and Han et al. (2006). Due to the variation of the optical properties of TSM, it is significant to study whether existing algorithms are adequate and reliable for the inversion of the concentration of TSM in the ECS for all seasons. Yet, up to now, the validation of the satellite retrieved TSM is still lack due to the insufficient of the in-situ data and the standard TSM product in the ECS. In the past three years, we have carried out four seasonal cruises covering the whole ECS, including the spring cruise from May to June 2011, the summer cruise in August 2009, the autumn cruise from November to December 2010, and the winter cruise from December 2009 to January 2010. In this paper, we firstly analyzed the spatial-temporal distribution of the TSM in the ECS. The results showed that there was remarkable seasonal variation with higher concentration in the winter half year and lower concentration in the summer half year. The concentration of TSM was higher inshore than that of offshore. The isolines were parallel to the shoreline as a whole. There was a turbid water tongue with notably seasonal variation spreading to southeast at the 29°N in the middle of the ECS. Finally, based on the remote sensing reflectance retrieved by the Aqua-MODIS and SeaWiFS data, the performance of the four inversion algorithms of TSM were evaluated using the in-situ measured TSM data in the ECS, including the Clark's model in the SeaDAS, Zhang's model, Han's model and Tassan's model. The results show that all of the TSM retrieved by the four models have large error as compared with the in-situ data, indicating the strong requirement of the improving the TSM retrieval in the ECS.
    Proc SPIE 09/2012;
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    ABSTRACT: Instead of the conventionally atmospheric correction algorithms using the near-infrared and shortwave infrared wavelengths, an alternative practical atmospheric correction algorithm using the ultraviolet wavelength for turbid waters (named UV-AC) is proposed for satellite ocean color imagery in the paper. The principle of the algorithm is based on the fact that the water-leaving radiance at ultraviolet wavelengths can be neglected as compared with that at the visible light wavelengths or even near-infrared wavelengths in most cases of highly turbid waters due to the strong absorption by detritus and colored dissolved organic matter. The UV-AC algorithm uses the ultraviolet band to estimate the aerosol scattering radiance empirically, and it does not need any assumption of the water's optical properties. Validations by both of the simulated data and in situ data show that the algorithm is appropriate for the retrieval of the water-leaving radiance in turbid waters. The UV-AC algorithm can be used for all the current satellite ocean color sensors, and it is especially useful for those ocean color sensors lacking the shortwave infrared bands. Moreover, the algorithm can be used for any turbid waters with negligible water-leaving radiance at ultraviolet wavelength. Based on our work, we recommend the future satellite ocean color remote sensors setting the ultraviolet band to perform the atmospheric correction in turbid waters.
    Optics Express 08/2012; 20(18):20754-70. · 3.55 Impact Factor
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    ABSTRACT: An extensive search of the literature and data banks identified studies of water-to-air CO2 exchange in 106 estuaries. Generally, pCO2 in upper estuaries is highly supersaturated with respect to the atmospheric CO2, and so a large amount of CO2 is released to the atmosphere per unit surface area. Wider mid and lower estuaries are associated with slower river flow and lower turbidity, and therefore greater biological productivity. Further, mixing with low-pCO2 seawater reduces pCO2 and, thereby, the water-to-air CO2 flux on the ocean side. All of the globe's estuaries release 0.26 Pg C/y to the atmosphere. However, nutrients that are provided by large rivers, such as the Amazon and Changjiang (Yangtze), and those entrained by the river plumes promote photosynthesis to such an extent that the water becomes undersaturated. Accordingly, the large river plumes become a CO2 sink even many hundred kilometers beyond the river mouth.
    Current Opinion in Environmental Sustainability 05/2012; 4(2):179–185. · 3.17 Impact Factor
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    ABSTRACT: Category 5 typhoon Megi was the most intense typhoon in 2010 of the world. It lingered in the South China Sea (SCS) for 5 d and caused a significant phytoplankton bloom detected by the satellite image. In this study, the authors investigated the ocean biological and physical responses to typhoon Megi by using chlorophyll-a (chl-a) concentration, sea surface temperature (SST), sea surface height anomaly (SSHA), sea surface wind measurements derived from different satellites and in situ data. The chl-a concentration (>3 mg/m3) increased thirty times in the SCS after the typhoon passage in comparison with the mean level of October averaged from 2002 to 2009. With the relationship of wind stress curl and upwelling, the authors found that the speed of upwelling was over ten times during typhoon than pre-typhoon period. Moreover, the mixed layer deepened about 20 m. These reveal that the enhancement of chl-a concentration was triggered by strong vertical mixing and upwelling. Along the track of typhoon, the maximum sea surface cooling (6–8°C) took place in the SCS where the moving speed of typhoon was only 1.4–2.8 m/s and the mixed layer depth was about 20 m in pre-typhoon period. However, the SST drop at the east of the Philippines is only 1–2°C where the translation speed of typhoon was 5.5–6.9 m/s and the mixed layer depth was about 40 m in pre-typhoon period. So the extent of the SST drop was probably due to the moving speed of typhoon and the depth of the mixed layer. In addition, the region with the largest decline of the sea surface height anomaly can indicate the location where the maximum cooling occurs.
    Acta Oceanologica Sinica -English Edition- 01/2012; 31(1). · 0.58 Impact Factor
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    ABSTRACT: This study investigated upper ocean responses to Category 5 Typhoon Megi, the most intense typhoon in 2010, using MODIS ocean color data, GHRSST L4 data, sea level anomaly data and sea surface wind data. Remarkable sea surface cooling(~6-7°C) with large area was observed mainly to the right side of typhoon track on 22 October, which was mainly attributed to the vertical mixing and upwelling induced by typhoon Megi. However, the sea ace temperature along the typhoon track increased after the landfall of typhoon and then decreased again. Two cold water patches were observed on 29 October, which were well coincident with two cores with maximum SLA decline. Therefore, we attributed the second cooling along the typhoon track to cyclonic eddies which were triggered by typhoon Megi. On the other hand, Strong upwelling was induced by typhoon Megi, which provided perfect conditions for the growth of phytoplankton and caused a significant phytoplankton bloom in the SCS. Relative to historical levels over the same period, the maximum chlorophyll a concentration increased about 20-30 times.
    Proc SPIE 10/2011;
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    ABSTRACT: The ocean satellite observation is more and more important to study the global change, protect ocean resource and implement ocean engineering for their large area cover and high frequency observation, which have already given us a global view of ocean environment parameters, including the sea surface temperature, ocean color, wind, wave, sea level and sea ice, etc... China has made great progress in ocean environment remote sensing over the last couple of years. These data are widely used for a variety of applications in ocean environment studies, coastal water quality monitoring environmental, fishery resources protection, development and utilization of fishery resources, coastal engineering and oceanography. But the data are no online information access and dissemination, no online visualization & browsing, no online query and analyze capability. To facilitate the application of the data and to help disseminating the data, a web-service system has developed. The system provides capabilities of online oceanic satellite information access, query, visualize and analyze. It disseminates oceanic satellite data to the users via real time retrieval, processing and publishing through standards-based geospatial web services. A region of interest can also be exported directly to Google Earth for displaying or downloaded. This web service system greatly improves accessibility, interoperability, usability, and visualization of oceanic satellite data without any client-side software installation.
    Proc SPIE 10/2011;
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    ABSTRACT: Synthetic aperture radar (SAR) can measure directional wave spectrum based on the closed nonlinear SAR-ocean mapping mechanism. The according wave spectrum retrieval algorithm has been developing for decades, but some limitations remain, like high wave number cut off in azimuthal direction and the need for the first guess spectrum. Wave spectrometer is a kind of new satellite-based real aperture radar (RAR) operating at low incidence, which has a narrow beam and scans complete 360° by antenna rotation. It derives wave spectrum by the simple linear relation between the wave spectrum and the modulation spectrum from the wave spectrometer. The linear coefficient can be estimated by the nadir beam or external wind speed information. This paper proposes a method on the wave spectrum estimation based on the joint measurement from synchronous SAR and wave spectrometer. Firstly, the modulation spectrum is derived from the signal spectrum of the wave spectrometer, from which the relative wave spectrum can be constructed. Then the relative wave spectrum is seen as the first guess spectrum for the wave spectrum retrieval of SAR image. Because the relative wave spectrum has the same pattern with the real wave spectrum but has different absolute energy, we can retrieve the directional wave spectrum by the iteration way based on the relative wave spectrum from the SAR image. This paper makes use of simulation technology to validate the joint measurement. The simulation compares the input spectrum and the retrieved one in terms of peak direction, peak wavelength and significant wave height, which has a deviation of 6°, 4m and 0.3m, respectively. Simulation results show the joint measurement has the feasibility for the retrieval of directional ocean wave spectrum.
    Proc SPIE 10/2011;
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    ABSTRACT: The operational atmospheric correction algorithm for Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS) uses the predefined aerosol models to retrieve aerosol optical properties, and their accuracy depends on how well the aerosol models can represent the real aerosol optical properties. In this paper, we developed a method to evaluate the aerosol models (combined with the model selection methodology) by simulating the aerosol retrieval using the Aerosol Robotic Network (AERONET) data. Our method can evaluate the ability of aerosol models themselves, independent of the sensor performance. Two types of aerosol models for SeaWiFS and MODIS operational atmospheric correction algorithms are evaluated over global open oceans, namely the GW1994 models and Ahmad2010 models. The results show that GW1994 models significantly overestimate the aerosol optical thicknesses and underestimate the Ångström exponent, which is caused by the underestimation of the scattering phase function. However, Ahmad2010 models can significantly reduce the overestimation of the aerosol optical thickness and the underestimation of the Ångström exponent as a whole, but this improvement depends on the backscattering angle. Ahmad2010 models have a significant improvement in the retrieval of the aerosol optical thickness at a backscattering angle less than 140°. For a backscattering angle larger than 140°, GW1994 models are better at retrieving the aerosol optical thickness than the Ahmad2010 models.
    Applied Optics 08/2011; 50(22):4353-64. · 1.69 Impact Factor
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    ABSTRACT: The Changjiang River is the third largest river of the annual flux around the world, which has a great impact on the ecosystem of the East China Sea and adjacent areas. Because of the shallow water, tide mixing and the runoff of the Changjiang River and Qiantang River, the suspended particulate matter (SPM) concentration is extremely high in the Changjiang Estuary, which is ever up to 2000mg/L. Due to the large water-leaving radiance at the near-infrared wavelength, the operational atmospheric correction algorithm for the open ocean can not be applied to this region, and the existing remote sensing algorithms for SPM may not be applicable for this extremely high turbidity waters. In this paper, we firstly apply the blue wavelength atmospheric correction algorithm to MERIS Level-1 data to get the reasonable spectral water-leaving radiances in the Changjiang Estuary. Based on the winter cruise data in 2007, a regional SPM algorithm was developed using the bands ratio of the normalized water-leaving radiances between 779nm and 560nm. This algorithm was validated by the summer cruise data in 2006, and the results show that the performance of the algorithm was very well, and there was good agreement between the retrieved data and in-situ measured concentrations of the SPM in the Changjiang Estuary, with the correlation coefficient of 0.98 in the logarithm form and the averaged absolute relative error of 27.2%, and the standard deviation of 20.8mg/l in the linear form. Finally, the seasonal variations of the SPM in the Changjiang Estuary were analyzed by the MERIS SPM maps retrieved by the algorithms developed in this paper.
    Proc SPIE 10/2010;

Publication Stats

75 Citations
44.18 Total Impact Points

Institutions

  • 2006–2014
    • State Oceanic Administration
      Tsingtao, Shandong Sheng, China
  • 2005–2014
    • Second Institute of Oceanography SOA
      Hang-hsien, Zhejiang Sheng, China
    • Technical Institute of Physics and Chemistry
      Peping, Beijing, China
  • 2011–2013
    • Zhejiang University
      • • Department of Earth Science
      • • Department of Ocean Science and Engineering
      Hang-hsien, Zhejiang Sheng, China