Recent changes of global ocean transparency observed by SeaWiFS

Abstract The water transparency usually quantized by the Secchi Disk depth, is a key index of water quality, and influences light penetration for phytoplankton photosynthesis. Although in situ measurements have provided century-long datasets in different regions, the seasonal and interannual variations as well as the long-term changes of ocean transparency at the global scale are still poorly understood. In the present study, based on the semi-analytic algorithm, the time series of the monthly global ocean transparency over Sept. 1997 to Nov. 2010 were retrieved from the satellite data observed by the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS). The seasonal and interannual variations of global ocean transparency were identified from the SeaWiFS-derived water transparency. Large seasonal variation amplitude occurred at the front zones between subtropical gyres and high latitude oceans. Moreover, ocean transparency increased in the Northern Hemisphere, while it decreased in the Southern Hemisphere, especially in the Southern Ocean from Sept. 1997 to Nov. 2010. The global mean ocean transparency decreased rapidly with a rate of −0.85 m yr−1 (p=0.001) between 1997 and 1999, followed by a small increase with a rate of 0.04 m yr−1 (p=0.05) over 2000–2010, which might be linked to changes of sea surface temperature with rapid decrease over 1998–1999 and slight increase over 2000–2010. These changes of water transparency may alter the available light for phytoplankton photosynthesis, and influence the thermal evolution of the upper ocean.

[1]  Xiaohan Liu,et al.  Predicting the light attenuation coefficient through Secchi disk depth and beam attenuation coefficient in a large, shallow, freshwater lake , 2012, Hydrobiologia.

[2]  Xianqiang He,et al.  Water-transparency (Secchi Depth) monitoring in the China Sea with the SeaWiFS satellite sensor , 2004, SPIE Remote Sensing.

[3]  David A. Siegel,et al.  Climate-driven trends in contemporary ocean productivity , 2006, Nature.

[4]  M. Oliver,et al.  Are ocean deserts getting larger? , 2009 .

[5]  Yan Bai,et al.  Summertime Changjiang River plume variation during 1998–2010 , 2014 .

[6]  Chuanmin Hu,et al.  The dispersal of the Amazon and Orinoco River water in the tropical Atlantic and Caribbean Sea: Obse , 2004 .

[7]  Victoria J. Coles,et al.  Seasonal variations in the Amazon plume‐related atmospheric carbon sink , 2007 .

[8]  J. Zaneveld,et al.  Robust underwater visibility parameter. , 2003, Optics express.

[9]  K. Ouchi,et al.  Validation of the semi-analytical algorithm for estimating vertical underwater visibility usiung MODIS data in the waters around Korea , 2013 .

[10]  F. Doblas-Reyes,et al.  Retrospective prediction of the global warming slowdown in the past decade , 2013 .

[11]  B. Worm,et al.  Global phytoplankton decline over the past century , 2010, Nature.

[12]  C. Chen,et al.  Satellite views of the episodic terrestrial material transport to the southern Okinawa Trough driven by typhoon , 2014 .

[13]  P. Falkowski,et al.  Phytoplankton productivity in the North Pacific ocean since 1900 and implications for absorption of anthropogenic CO2 , 1992, Nature.

[14]  Chuanmin Hu,et al.  Influence of the Three Gorges Dam on total suspended matters in the Yangtze Estuary and its adjacent coastal waters: Observations from MODIS , 2014 .

[15]  C. McClain,et al.  Recent trends in global ocean chlorophyll , 2005 .

[16]  Xin Liu,et al.  Source diagnostic and weathering indicators of oil spills utilizing bicyclic sesquiterpanes , 2013, Acta Oceanologica Sinica.

[17]  Francisco P Chavez,et al.  Marine primary production in relation to climate variability and change. , 2011, Annual review of marine science.

[18]  K. Prasad,et al.  Ocean Color Algorithms for Estimating Water Clarity (Secchi Depth) from Sea WiFS , 2000 .

[19]  Joaquim I. Goes,et al.  Blooms of Noctiluca miliaris in the Arabian Sea - An In Situ and Satellite Study , 2008 .

[20]  Yan Bai,et al.  Areas of the global major river plumes , 2013, Acta Oceanologica Sinica.

[21]  Melanie Abecassis,et al.  Ocean's least productive waters are expanding , 2008 .

[22]  Yan Bai,et al.  Ecological anomalies in the East China Sea: impacts of the Three Gorges Dam? , 2007, Water research.

[23]  Donald C. Pierson,et al.  Relationship between the attenuation of downwelling irradiance at 490 nm with the attenuation of PAR (400 nm-700 nm) in the Baltic Sea , 2008 .

[24]  Weilin Hou,et al.  Secchi disk depth: A new theory and mechanistic model for underwater visibility , 2015 .

[25]  J. Gattuso,et al.  Light availability in the coastal ocean: Impact on the distribution of benthic photosynthetic organisms and their contribution to primary production , 2006 .

[26]  Antoine Mangin,et al.  Ocean transparency from space: Validation of algorithms estimating Secchi depth using MERIS, MODIS and SeaWiFS data , 2011 .

[27]  Rudolph W. Preisendorfer,et al.  Secchi disk science: Visual optics of natural waters1 , 1986 .

[28]  K. Banse,et al.  Winter blooms of phytoplankton in the Arabian Sea as observed by the Coastal Zone Color Scanner , 1986 .

[29]  E. Boss,et al.  Regional to global assessments of phytoplankton dynamics from the SeaWiFS mission , 2013 .

[30]  R. Arnone,et al.  Deriving inherent optical properties from water color: a multiband quasi-analytical algorithm for optically deep waters. , 2002, Applied optics.

[31]  T. Aarup.  Transparency of the North Sea and Baltic Sea - a Secchi depth data mining study , 2002 .

[32]  Charles R. McClain,et al.  Subtropical Gyre Variability Observed by Ocean Color Satellites , 2004 .

[33]  Shu Gao,et al.  Changes in material fluxes from the Changjiang River and their implications on the adjoining continental shelf ecosystem , 2008 .

[34]  Dag L. Aksnes,et al.  Centennial changes in water clarity of the Baltic Sea and the North Sea , 2013 .

[35]  M. Bauer,et al.  A procedure for regional lake water clarity assessment using Landsat multispectral data , 2002 .

[36]  P. J. Werdell,et al.  A multi-sensor approach for the on-orbit validation of ocean color satellite data products , 2006 .

[37]  Charles S. Yentsch,et al.  Global patterns of ocean transparency: Implications for the new production of the open ocean , 1988 .

[38]  R. Arnone,et al.  A model for the diffuse attenuation coefficient of downwelling irradiance , 2005 .

[39]  Yan Bai,et al.  Remote sensing of salinity from satellite-derived CDOM in the Changjiang River dominated East China Sea , 2013 .

[40]  J. Brock,et al.  Interannual variability in phytoplankton blooms observed in the northwestern Arabian Sea during the southwest monsoon , 1992 .

[41]  Chuanmin Hu,et al.  Remote sensing of water clarity in Tampa Bay , 2007 .

[42]  James L. Mueller,et al.  SeaWiFS Algorithm for the Diffuse Attenuation Coefficient K(490) Using Water-Leaving Radiances at 490 and 555nm , 2000 .

[43]  Q. Cheng,et al.  Satellite views of the seasonal and interannual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011) , 2013 .

[44]  T. Platt,et al.  An estimate of global primary production in the ocean from satellite radiometer data , 1995 .