Project Funding: 2014 - 2016

NRA: 2013 NASA: The Science of Terra and Aqua   

Funded by NASA

Abstract:
The theme of the proposed project is ocean-color remote sensing using MISR data. The chief objective is to develop, implement, and evaluate atmospheric correction algorithms that will allow the generation of a new product: Marine reflectance from MISR data. To achieve this objective, highly relevant to the solicitation under element 2.2 "Algorithms - New Data Products", several algorithms, with various levels of complexity, will be investigated. Depending on performance, theoretical and experimental, and practical considerations, the best algorithm will be selected for processing operationally MISR imagery into marine reflectance. The approach to atmospheric correction will involve two consecutive steps: (1) correction of molecular and aerosol scattering effects, and (2) correction of aerosol absorption effects. Various assumptions will be made, that will be relaxed as algorithm complexity is increased. In one scheme, the ocean will be assumed to be black in the red and near infrared, allowing the use of spectral bands at 672 and 867 nm to determine aerosol scattering. To deal with turbid waters, only multi-angle measurements at 867 nm will be used to determine aerosol scattering. Alternatively, a classic iterative scheme will be implemented that uses a bio-optical model to relate marine reflectance in the visible to marine reflectance in the near infrared. All the algorithms will exploit the unique ability of MISR to measure in multiple directions, based on concepts developed for POLDER.  The algorithms will be developed using simulated data, evaluated theoretically, and applied, for testing and evaluation purposes, to selected MISR imagery acquired over Case 1 and Case 2 waters, in situations of absorbing and non-absorbing aerosols. The estimates of marine reflectance obtained using MISR data will be compared with other satellite estimates, i.e., from SeaWiFS and MODIS data. The ocean-color retrievals will be also evaluated against in situ data collected during comprehensive campaigns (such as ACE-Asia dedicated to Asian dust) and at long-term validation sites (such as the Chesapeake Lighthouse affected by US pollution), and data available from bio-optical archives. A comprehensive calibration plan will allow a routine check-of-calibration of the MISR cameras, especially cross-calibration, critical to using quantitatively the multi- angle observations. The investigation will provide the basis for producing operationally a new ocean color data set, complementary to existing data sets, using algorithms that will enable accurate estimates of phytoplankton pigment concentration, hence primary production, in difficult- to-correct, i.e., dust-contaminated or polluted, oceanic areas, and in optically complex waters. This is significant, since the areas involved, including the coastal zone and estuaries, are vast and tend to be very productive. The daily coverage of the MODIS ocean color products will be improved, since some of the gaps in the imagery due to sun glint will be filled by the MISR retrievals and estimates will be obtained over regions affected by absorbing aerosols (generally masked in the standard products). This will contribute to resolve better seasonal biological phenomena such as phytoplankton blooms in the open ocean and "events" linked to wind forcing in the coastal zone. Furthermore, dealing with absorbing aerosols in the ocean-color imagery by exploiting the angular information provided by MISR will prepare future satellite missions, namely ACE and PACE, which are being designed to carry instruments with not only spectral, but also multi-angular capability.

More details may be found in the following project profile(s):

• NASA Ocean Biology & Biogeochemistry (OBB) Project Profile