Improvement in airsea flux estimates derived from satellite observations

Type Article
Date 2013-07
Language English
Author(s) Bentamy Abderrahim5, Grodsky Semyon A.1, Katsaros Kristina2, Mestas-Nunez Alberto M.3, Blanke Bruno4, 6, Desbiolles Fabien5
Affiliation(s) 1 : Univ Maryland, Dept Atmospher & Ocean Sci, College Pk, MD 20742 USA.
2 : Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA.
3 : Texas A&M Univ Corpus Christi, Dept Phys & Environm Sci, Corpus Christi, TX USA.
4 : UBO, IRD, IFREMER, LPO,CNRS,UMR 6523, Paris, France.
Source International Journal Of Remote Sensing (0143-1161) (Taylor & Francis Ltd), 2013-07 , Vol. 34 , N. 14 , P. 5243-5261
DOI 10.1080/01431161.2013.787502
WOS© Times Cited 30
Abstract A new method is developed to estimate daily turbulent airsea fluxes over the global ocean on a 0.25 degrees grid. The required surface wind speed (w(10)) and specific air humidity (q(10)) at 10m height are both estimated from remotely sensed measurements. w(10) is obtained from the SeaWinds scatterometer on board the QuikSCAT satellite. A new empirical model relating brightness temperatures (T-b) from the Special Sensor Microwave Imager (SSM/I) and q(10) is developed. It is an extension of the author's previous q(10) model. In addition to T-b, the empirical model includes sea surface temperature (SST) and airsea temperature difference data. The calibration of the new empirical q(10) model utilizes q(10) from the latest version of the National Oceanography Centre airsea interaction gridded data set (NOCS2.0). Compared with mooring data, the new satellite q(10) exhibits better statistical results than previous estimates. For instance, the bias, the root mean square (RMS), and the correlation coefficient values estimated from comparisons between satellite and moorings in the northeast Atlantic and the Mediterranean Sea are 0.04gkg(1), 0.87gkg(1), and 0.95, respectively. The new satellite q(10) is used in combination with the newly reprocessed QuikSCAT V3, the latest version of SST analyses provided by the National Climatic Data Center (NCDC), and 10m air temperature estimated from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA-Interim), to determine three daily gridded turbulent quantities at 0.25 degrees spatial resolution: surface wind stress, latent heat flux (LHF), and sensible heat flux (SHF). Validation of the resulting fields is performed through a comprehensive comparison with daily, in situ values of LHF and SHF from buoys. In the northeast Atlantic basin, the satellite-derived daily LHF has bias, RMS, and correlation of 5Wm(2), 27Wm(2), and 0.89, respectively. For SHF, the statistical parameters are 2Wm(2), 10Wm(2), and 0.94, respectively. At global scale, the new satellite LHF and SHF are compared to NOCS2.0 daily estimates. Both daily fluxes exhibit similar spatial and seasonal variability. The main departures are found at latitudes south of 40 degrees S, where satellite latent and sensible heat fluxes are generally larger.
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