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A comparative assessment of surface wind speed and sea surface temperature over the Indian ocean by TMI, MSMR, and ERA-40

Parekh, A and Sharma, R and Sarkar, A (2007) A comparative assessment of surface wind speed and sea surface temperature over the Indian ocean by TMI, MSMR, and ERA-40. Journal of Atmospheric and Oceanic Technology, 24 (6). pp. 1131-1142.

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Abstract

A 2-yr (June 1999-June 2001) observation of ocean surface wind speed (SWS) and sea surface temperature (SST) derived from microwave radiometer measurements made by a multifrequency scanning microwave radiometer (MSMR) and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is compared with direct measurements by Indian Ocean buoys. Also, for the first time SWS and SST values of the same period obtained from 40-yr ECMWF Re-Analysis (ERA-40) have been evaluated with these buoy observations. The SWS and SST are shown to have standard deviations of 1.77 m s-1 and 0.60 K for TMI, 2.30 m s-1 and 2.0 K for MSMR, and 2.59 m s-1 and 0.68 K for ERA-40, respectively. Despite the fact that MSMR has a lower-frequency channel, larger values of bias and standard deviation (STD) are found compared to those of TMI. The performance of SST retrieval during the daytime is found to be better than that at nighttime. The analysis carried out for different seasons has raised ah important question as to why one spaceborne instrument (TMI) yields retrievals with similar biases during both pre- and postmonsoon periods and the other (MSMR) yields drastically different results. The large bias at low wind speeds is believed to be due to the poorer sensitivity of microwave emissivity variations at low wind speeds. The extreme SWS case study (cyclonic condition) showed that satellite-retrieved SWS captured the trend and absolute magnitudes as reflected by in situ observations, while the model (ERA-40) failed to do so. This result has direct implications on the real-time application of satellite winds in monitoring extreme weather events.

Item Type: Article
Additional Information: Copyright of this article belongs to American Meteorological Society.
Uncontrolled Keywords: Atmospheric temperature; Microwaves; Radiometers; Rain; Real time systems; Satellite imagery; Wind effects, Microwave radiometer; Sea surface temperature; Surface wind speed, Oceanography, Atmospheric temperature; Microwaves; Oceanography; Radiometers; Rain; Real time systems; Satellite imagery; Wind effects, buoy system; microwave radiometer; monitoring system; real time; satellite imagery; sea surface; sea surface temperature; surface wind; wind velocity, Indian Ocean
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 06 Feb 2015 06:32
Last Modified: 06 Feb 2015 06:32
URI: http://moeseprints.incois.gov.in/id/eprint/1895

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