An Introduction to the Near–Real–Time QuikSCAT Data

Abstract

The NASA Quick Scatterometer (QuikSCAT ) satellite carries the SeaWinds instrument, the first satellite-borne scanning radar scatterometer. QuikSCAT, which was launched on 19 June 1999, is designed to provide accurate ocean surface winds in all conditions except for moderate to heavy rain (i.e., except for vertically integrated rain rate Ͼ2.0 km mm h Ϫ1 , the value used to tune the SeaWinds rain flag). QuikSCAT data are invaluable in providing high-quality, high-resolution winds to detect and locate precisely significant meteorological features and to produce accurate ocean surface wind analyses. QuikSCAT has an 1800-kmwide swath. A representative swath of data in the North Atlantic at 2200 UTC 28 September 2000, which contains several interesting features, reveals some of the capabilities of QuikSCAT. Careful quality control is vital for flagging data that are affected by rain and for flagging errors during ambiguity removal. In addition, an understanding of the instrument and algorithm characteristics provides insights into the factors controlling data quality for QuikSCAT. For example data quality is reduced for low wind speeds, and for locations either close to nadir or to the swath edges. The special data characteristics of the QuikSCAT scatterometer are revealed by examining the likelihood or objective function. The objective function is equal to the sum of squared scaled differences between observed and simulated normalized reflected radar power. The authors present typical examples and discuss the associated data quality concerns for different parts of the swath, for different wind speeds, and for rain versus no rain.

Usability of Best Track Data in Climate Statistics in the Western North Pacific

“…Scatterometers measure instantaneous ocean surface wind vectors at 10-m height with a grid-typical resolution of 25 km and are widely used in operationally prepared analyses and forecasts SEPTEMBER 2012 B A R C I K O W S K A E T A L . (Bourassa et al 2010;Brennan et al 2009;Hoffman and Leidner 2005). They are intended to provide accurate ocean surface winds in all weather conditions except for rain conditions that occur often during high winds.…”

“…Because of a positive bias which occurs in QuikSCAT data for tropical depressions (Hoffman and Leidner 2005) and frequently changing procedures in operational centers to identify this phase, the analysis focuses on concurrent records in BTDs during tropical storm stage. As JTWC and JMA provide information about conversion tables in use, we use the JMA dataset remapped to 1-min-averaged wind speed using the DT table (as described in the previous section).…”

High‐resolution simulation over central Europe: assimilation experiments during COPS IOP 9c

“…Most assimilation schemes include conventional observations like SYNOP stations or radiosondes (TEMP). To further improve the initial conditions, remote-sensing observations like SSM/I brightness temperatures (Hollinger, 1989;Chen, 2007;Singh et al, 2008), QuickSCAT sea surface winds (Hoffman and Leidner, 2005;Chen, 2007;Singh et al, 2008) and Atmospheric Motion Vectors (AMVs; EUMETSAT, 2009) are used in addition. The largest advantages of remotesensing observations are that they are available much more frequently than conventional observations and that they are also available over the ocean.…”

Insights on the OAFlux ocean surface vector wind analysis merged from scatterometers and passive microwave radiometers (1987 onward)

“…The SeaWinds scatterometer on the NASA's QuikSCAT mission uses a dual-beam, conically scanning antenna operating at a frequency of 13.4 GHz (Ku-band) [Spencer et al, 2000;Hoffman and Leidner, 2005]. Backscatter measurements were collected simultaneously at constant incidence angles of 46 for the inner beam, and 54 for the outer beam, with horizontal and vertical polarizations, respectively.…”