Establishing A Mapping Methodology For NSCAT Winds.
Abstract
A methodology is presented for mapping swath-oriented NASA scatterometer (NSCAT) wind data into gridded maps suitable for forcing ocean circulation models. NSCAT samples the winds over the equatorial Pacific Ocean unevenly in both space and time, and care must be taken in mapping them onto a grid to prevent aliasing the fields. It was necessary to develop a "true" wind field with which to test the mapping methodology. Prior to the availability of NSCAT data, the European Centre for Medium-Range Weather Forecasts (ECMWF) and Fleet Numerical Meteorology and Oceanography Center (FNMOC) analysis wind fields were studied. Spectral analysis of the ECMWF and FNMOC wind fields showed a drastic drop in energy at scales smaller than 600 km. These energy levels were "pumped up" in the Fourier domain to represent a true wind field more accurately. These "true" wind fields were converted to pseudostress, subsampled with the known NSCAT sampling pattern (termed "synthetic NSCAT" winds), and then objectively averaged. A study of the expected errors of the mapped pseudo- stress was conducted using a convarience function of the equatorial Pacific wind field determined with data from the Tropical Atmosphere Ocean (TAO) buoy array. A 5-day, 20 resolution was chosen for the daily mapped pseudostress. Comparisons of the "true" winds converted to pseudostress and the mapped synthetic NSCAT pseudostress show errors consistent with the expected values. Maps made of actual NSCAT data are also presented and discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1998
- Accession Number
- ADA347135
Entities
People
- K. A. Kelly
- M. Spillane
- Michael J. McPhaden
- S.M. Dickinson
- Satpreet H. Singh
Organizations
- University of Washington