Location, Platform, Instrument. The Air-Sea Interaction Tower (ASIT) is located about 3 km offshore in 15.6 m of water. The SeaPRISM is deployed on ASIT at the Martha's Vineyard Coastal Observatory (latitude=41.3; longitude=70.57).
The Air-Sea Interaction Tower (ASIT) is located about 3 km offshore in 15.6 m of water. The SeaPRISM is deployed on ASIT at the Martha's Vineyard Coastal Observatory (latitude=41.3; longitude=70.57).
Ten Year Practice of Satellite Ocean Color and Aerosol Product Validation in the US Northeastern Coastal Region using AERONET-Ocean Color MeasurementsHui Feng1, Heidi Sosik2 , and Tim Moore1 1: University of New Hampshire; 2 : Woods Hole Oceanographic Institution
The optical complexity of waters and atmospheres in coastal environments leads to potential issues in the quality of satellite ocean color and aerosol products. Uncertainties of satellite retrievals in the coastal region result from inaccuracies in the atmospheric correction and in-water constituent retrieval algorithms. Quantifying these uncertainties (i.e. satellite product validation) requires a comprehensive methodology, including high-quality in-situ measurements, retrieval algorithm assessment, and match up analysis. Thus, since early 2004, an automatic radiance measurement system, AEROENT-Ocean Color (AEROENT-OC, SeaPRISM) has been deployed at the Air-Sea Interaction Tower (ASIT) near the Martha's Vineyard Coastal Observatory (See Figure at left)
This study presents the following parts: 1) an inter-validation of MODIS-Aqua ocean color products by reprocessing (R2013.0;R2012.0 and R2010), and SeaWiFS R2010 in terms of AERONET-OC measurements as a reference (III); 2) a cross validation of MODIS-Aqua aerosol products by Ocean Color and Atmosphere research team algorithms based on the northeast coastal AERONET measurements (IV); and 3) a validation of MVCO QAA-retrieved absorption components from SeaPRISM radiance measurements vs. directly measured ones (V). Summary is given in VI.
III. Validation of satellite water leaving radiance product from different missions reprocessing
IV. Cross validation of MODIS-Aqua aerosol properties by Ocean Color (OCN) and Atmosphere (ATM) teams
MODIS-Aqua reprocessing R2012 vs. R2013
TOP: MODIS-OCN vs. MODIS-ATM AOT(550); MIDDLE: MODIS-ATM vs. AERONET AOT(870); BOTTOM: MODIS-OCN vs. AERONET Ångström exponent α(550, 870)
(TOP), (MIDDLE) and (BOTTOM): Distributions of aerosol optical thickness AOT(550), AOT(870), and Ångström exponent α(550, 870)
- MODIS-ATM on Aqua: Collection 5
- MODIS-OC on Aqua:
*reprocessing 2012.1 (from 2002 to 2010)
*reprocessing 2013.0 (from 2011 to 2013)
- AERONET Level-2 data from 11 coastal sites (4 over oceans)
- Years 2002 - 2013
Scatter plots: satellite MODIS-retrieved nLw in R2012 (Blue dot) and R2013 (Red circle) vs. SeaPRISM nLw at 412, 443, 547, and 667nm ( from the left to the right). The statistics of correlation coefficient r2, mean percentage error and absolute percentage errors, and number of match ups observations, are all given for each panel.
MODIS-Aqua reprocessing 2012
SeaWiFS reprocessing 2010
Scatter plots of SeaWiFS-retrieved vs.AERONET-OC (SeaPRISM) measured nLw at 412, 443, 490,510, 555 and 670 nm from top left to bottom right. N =92 is the number of match-ups, and uncertainty measures of δ(%), |δ|(%) and r2 are indicated. Products are from AERONET-OC Level-2 data and SeaWiFS R2010.
Scatter plots of MODIS-retrieved vs.AERONET-OC (SeaPRISM) measured nLw at 412, 443, 488, 531, 547, and 667 nm from top left to bottom right. N =185 is the number of match-ups, and uncertainty measures of δ(%), |δ|(%) and r2 are indicated. Products are from AERONET-OC Level-2 data and MODIS-Aqua R2012 in the period 2004-2010.
MODIS-Aqua SWIR-based Vs. NIR-based atmosphere correction
SWIR based atmospheric correction does not help to improve nLw retrieval performance (Not shown )
Upper panels: Scatter plot showing the SeaPRISM QAA vs. in situ absorption components (left) aT (total absorption ), (mid) adg and (right) aph (wavelenthes are indicated by colors).
Lower panels: in situ (blue) and the SeaPRISM QAA (red) absorptions : (left) aT, (mid) adg and (right) aph
Time series: (top): aph (443); (middle) aph (547); (bottom) adg (443); aph .
Red points are SeaPRISM QAA retrievals; Blue refers to in situ measurements; Black lines are 30 day binned SeaPRISM QAA retrievals.
NASA Ocean Color Research Team Meeting, Silver Spring, Maryland 5-7 May 2014