Publications

Chen, SL; Hu, CM; Byrne, RH; Robbins, LL; Yang, B (2016). Remote estimation of surface pCO(2) on the West Florida Shelf. CONTINENTAL SHELF RESEARCH, 128, 10-25.

Abstract
Surface pCO(2) data from the West Florida Shelf (WFS) have been collected during, 25 cruise surveys between 2003 and 2012. The data were scaled up using remote sensing measurements of surface water properties in order to provide a more nearly synoptic map of pCO(2) spatial distributions and describe their temporal variations. This investigation involved extensive tests of various model forms through parsimony and Principal Component Analysis, which led to the development of a multi-variable empirical surface pCO(2) model based on concurrent MODIS (Moderate Resolution Imaging Spectroradiometer) estimates of surface chlorophyll a concentrations (CHL, mg m(-3)), diffuse light attenuation at 490 nm (Kd_Lee, m(-1)), and sea surface temperature (SST, degrees C). Validation using an independent dataset showed a pCO(2) Root Mean Square Error (RMSE) of < 12 mu atm and a 0.88 coefficient of determination (R-2) for measured and model-predicted pCO(2) ranging from 300 to 550 atm. The model was more sensitive to SST than to CHL and Kd_Lee, with a 1 degrees C change in SST leading to a similar to 16 mu atm change in the predicted pCO(2). Application of the model to the entire WFS MODIS time series between 2002 and 2014 showed clear seasonality, with maxima (similar to 450 mu atm) in summer and minima (similar to 350 mu atm) in winter. The seasonality was positively correlated to SST (high in summer and low in winter) and negatively correlated to CHL and Kd_Lee (high in winter and low in summer). Inter-annual variations of pCO(2) were consistent with inter-annual variations of SST, CHL, and Kd_Lee. These results suggest that surface water pCO(2) of the WFS can be estimated, with known uncertainties, from remote sensing. However, while the general approach of empirical regression may work for waters from other areas of the Gulf of Mexico, model coefficients need to be empirically determined in a similar fashion.

DOI:
10.1016/j.csr.2016.09.004

ISSN:
0278-4343