TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 56 (No. 5), pp. 495-505, 2000

Evaluation of Vector Winds Observed by NSCAT in the Seas around Japan

Harunobu Masuko1, Kohei Arai2, Naoto Ebuchi3*, Masanori Konda4, Masahisa Kubota5, Kunio Kutsuwada5, Teruko Manabe6, Akira Mukaida7, Tetsuo Nakazawa8, Atsushi Nomura9, Akira Shibata10 and Yoshihiko Tahara9

1Communications Research Laboratory, Ministry of Posts and Telecommunications, 4-2-1, Nukui-kita-machi, Koganei, Tokyo 184-8795, Japan
2Department of Information Science, Saga University, 1 Honjo, Saga 840-8502, Japan
3Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan
4Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
5School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-8610, Japan
6Climate and Marine Department, Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan
7Remote Sensing Technology Center of Japan, 1-9-9 Roppongi, Minato-ku, Tokyo 106-0032, Japan
8Meteorological Research Institute, 1-1 Nagamine, Tsukuba 305-0052, Japan
9Forecast Department, Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan
10National Space Development Agency of Japan, 1-9-9 Roppongi, Minato-ku, Tokyo 106-0032, Japan

(Received 18 May 1999; in revised form 15 March 2000; accepted 19 March 2000)

Abstract: In order to validate wind vectors derived from the NASA Scatterometer (NSCAT), two NSCAT wind products of different spatial resolutions are compared with observations by buoys and research vessels in the seas around Japan. In general, the NSCAT winds agree well with the wind data from the buoys and vessels. It is shown that the root-mean-square (rms) difference between NSCAT-derived wind speeds and the buoy observations is 1.7 ms-1, which satisfies the mission requirement of accuracy, 2 ms-1. However, the rms difference of wind directions is slightly larger than the mission requirement, 20°. This result does not agree with those of previous studies on validation of the NSCAT-derived wind vectors using buoy observations, and is considered to be due to differences in the buoy observation systems. It is also shown that there are no significant systematic trends of the NSCAT wind speed and direction depending on the wind speed and incidence angle. Comparison with ship winds shows that the NSCAT wind speeds are lower than those observed by the research vessels by about 0.7 ms-1 and this bias is twice as large for data observed by moving ships than by stationary ships. This result suggests that the ship winds may be influenced by errors caused by ship's motion, such as pitching and rolling.

*Corresponding author E-mail: ebuchi@ocean.caos.tohoku.ac.jp

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