QSCAT

A tabular summary provides key details. Additional information is given in written descriptions following the table. The names of the products in the table are linked to the written descriptions. These descriptions include contact information, sites from which the data is available (or email contact with the people who will send the data), links to documentation, links to read routines, and references.

Data Set	Spatial Coverage	Spatial Grid	Temporal Coverage	Temporal Grid	Data Fields	Non-QSCAT Input	Processing Technique
Project Level 3	Global (in swaths)	0.25x0.25°	20 July 1999 and ongoing	Daily	u, v, ?	None	Vector average within swaths
COAPS/FSU Objectively Analyzed	Global	1x1°	20 July 1999 and ongoing	6 hourly	UW, VW	None	Variational method, with objectively determined weights
COAPS/FSU Objectively Analyzed	Gulf of Mexico	0.5x0.5°	20 July 1999 and ongoing	6 hourly	UW, VW	None	Variational method, with objectively determined weights
Blended QSCAT/NCEP u,v Surface Winds from Morzel, Milliff, and Chin	Global	0.5x0.5°	July 1999 and ongoing	6 hourly	u, v	NCEP winds	wavelet based multiresolution analysis: QSCAT in swaths; NCEP in gaps, enhanced with QSCAT-derived high-wavenumber variability
Tang and Liu	Global	0.5x0.5°	20 July 1999 and ongoing	12 hourly	u, v	ECMWF	Successive correction

Definitions for Symbols

All scatterometer derived wind and pseudostress quantities are equivalent neutral values, unless explicitly stated otherwise. Further explanations for the winds, pseudostresses, and stresses are available.

Field Variable	Definition
u	West-to-East component of the wind (positive Eastward)
v	South-to-North component of the wind (positive Northward)
w	Wind speed. Note that wind speeds can be averaged as vectors or scalars, and that the differences can be substantial. See the detailed product description for the type of averaging.
UW	West-to-East component of the pseudostress (positive Eastward)
VW	South-to-North component of the pseudostress (positive Northward)
tx	West-to-East component of the surface stress (positive Eastward)
ty	South-to-North component of the surface stress (positive Northward)

Additional Information

Project Level 3 Product

Global, daily, vector averaged maps of QuikSCAT winds, derived from daily bins the Level 2/50 km wind vectors, on 0.25 degree by 0.25 degree grids. Winds are available only where there were observations. Reference height is 10m. A table describing this and other gridded products is at the top of this page.

• Deliverables:
  Data - Daily gridded wind data
  Read Software - FORTRAN, C and IDL
  Documentation - User's Manual, NSP guide, web site

• Where:
  Available through anonymous FTP here

• Contact:
  Kelly Perry
  E-mail: kelly@poseidon.jpl.nasa.gov

• Reference:
  JPL, ?

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COAPS/FSU Objectively Analyzed

Four times daily fields of pseudostress are produced using a variational approach (direct minimization) with tuning parameters objectively determined using Generalized Cross Validation (GCV). This method greatly reduces spurious curl and divergence that occur near swath edges. These products are on either 0.5 x 0.5 or 1 x 1 degree grids. Data fields are pseudostress components. Rain-contaminated scatterometer measurements are excluded from the blending product. Reference height is 10m. A table describing this and other gridded products is at the top of this page.

• Deliverables:
  Read Software - FORTRAN, C, IDL
  Documentation - Available here, Animations of these winds

• Where:
  COAPS Scatterometry Data Download Area
  Tools are available for converting NetCDF files to ASCII here. Free read software for UNIX, Macs, and PCs is available from Unidata. Additional information is available here.

• Contact:
  Dr. Mark Bourassa
  Phone : 850-644-6923
  E-mail : bourassa@coaps.fsu.edu

• References:
  • Legler, D. M., M. A. Bourassa, A. D. Rao, and J. J. O'Brien, 1998: NSCAT Surface Wind Fields Using Optimally Tuned Direct Minimization Techniques. Papers from 9th Conference on Interaction of Sea and Atmosphere, Phoenix, AZ, American Meteorological Society, 32-35.
  • Pegion, P. J., M. A. Bourassa, D. M. Legler, and J. J. O'Brien, 2000: Objectively-derived daily "winds" from satellite scatterometer data. Mon. Wea Rev., in press.

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Blended Winds from Morzel, Milliff, and Chin

Global 6-hourly maps of ocean surface winds are derived from a space and time blend of QSCAT scatterometer observations and NCEP analyses. This blending method creates global fields by retaining QSCAT wind retrievals in swath regions, and in the unsampled regions (nadir and interswath gaps)augmenting the low-wavenumber NCEP fields with a high-wavenumber component that is derived from monthly regional QSCAT statistics. Rain-contaminated scatterometer measurements are excluded from the blending product. Reference height is 10m. A table describing this and other gridded products is at the top of this page.

• Deliverables:
  Data - Global, 6-hourly blended QSCAT/NCEP wind vectors on 0.5x0.5 grid.
  Read Software - FORTRAN
  Documentation - Available at Colorado Research

• Where:
  Available here

• Contact:
  Jan Morzel
  Phone: (303) 415-9701 x206
  Email: morzel@co-ra.com

• References
  • A similarily derived data set for NSCAT (September 1996 - June 1997) is described in the appendix of Milliff, R.F., W.G. Large, J. Morzel, G. Danabasoglu, and T.M. Chin, 1999: Ocean General Circulation Model Sensitivity to Forcing from Scatterometer Winds. J. Geophys. Res., C5, 11337-11358.
  • The details of the blending methology are the subject of Chin, T.M., R.F. Milliff, and W.G. Large, 1998: Basin-Scale High-Wavenumber Sea Surface Wind Fields fromMultiresolution Analysis of Scatterometer Data. Journal of Atmospheric and Oceanic Technology, 15, 741-763.
  • Global maps of wind stress curl have been computed from the NSCAT blended product, and compared with curl from NCEP analyses in Milliff, R.F., and J. Morzel, 2001: The Global Distribution of the Time-average Wind Stress Curl from NSCAT. Journal of the Atmospheric Sciences, Vol. 58, No. 2, 109-131.
  • The QSCAT blended wind product provides a useful compromise between ubiquitous but coarse and contaminated NCEP, and intermittent by high-resolution QSCAT surface wind products, as described in Morzel, J., R.F. Milliff, M. Freilich, and B. Vanhoff, 2001: Global Annual Average Wind Stress Curl and Divergence from QSCAT: Comparisons between QSCAT, NCEP, and a Blended Product. This web page is based on a presentation at the NASA OceanographicScientific Conference, April 2001, Miami Beach, FL.

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Tang and Liu

Twice daily global wind fields produced by successive corrections using scatterometer winds, with QuikSCAT monthly averaged wind data as the initial fields. This product is based on the near real-time data from NOAA, rather than the delayed product from JPL or RSS. Rain-contaminated data are not removed.Spatial grid is 0.5 degree by 0.5 degree. The gridded products are wind components. A table describing this and other gridded products is at the top of this page.

• Deliverables:
  Data - Twice daily gridded wind data
  Read Software - IDL
  Documentation - N/A

• Where:
  Available here

• Contact:
  Wenqing Tang
  Phone: 818-354-8199
  E-mail: wqt@seanet.jpl.nasa.gov

• Reference:
  • Tang, W. and W. T. Liu, 1996: Objective interpolation of scatterometer winds. JPL publication 96-19. 16pp.