The dependence of nadir ocean surface emissivity on wind vector as measured with microwave radiometer

Author

Tran, Ngan ; Vandemark, Douglas ; Ruf, Christopher S. ; Chapron, Bertrand

Author_Institution

Wallops Flight Facility, NASA Goddard Space Flight Center, Wallops Island, VA, USA

Volume

40

Issue

2

fYear

2002

fDate

2/1/2002 12:00:00 AM

Firstpage

515

Lastpage

523

Abstract

Global brightness temperature observations of the TOPEX/Poseidon microwave radiometer (TMR) at 18, 21, and 37 GHz have been collocated with near-simultaneous SeaWinds wind vector data as well as with monthly sea surface temperature and salinity products. The combined data allow us to study the dependence of zenith-directed ocean surface emissivity, at each frequency, upon both wind speed and direction. Results show a clear two-branch wind speed dependence; weak and linear below 7 m s^-1 with an increase in sensitivity above that point. The observed emissivity also depends on the angle between the wind direction and TMR´s antenna polarization orientation, providing satellite confirmation of aircraft-derived results. There is little change in these wind vector dependencies with frequency

Keywords

oceanographic techniques; oceanography; radiometry; remote sensing; wind; 18 GHz; 21 GHz; 37 GHz; SeaWinds wind vector data; TOPEX/Poseidon microwave radiometer; antenna polarization orientation; global brightness temperature observations; monthly sea surface temperature; nadir ocean surface emissivity; salinity; two-branch wind speed dependence; wind direction; wind vector dependencies; zenith-directed ocean surface emissivity; Brightness temperature; Directive antennas; Frequency; Microwave radiometry; Ocean temperature; Polarization; Satellite antennas; Sea surface; Vectors; Wind speed;

fLanguage

English

Journal_Title

Geoscience and Remote Sensing, IEEE Transactions on

Publisher

ieee

ISSN

0196-2892

Type

jour

DOI

10.1109/36.992827

Filename

992827