SeaWinds on ADEOS-II Research Topics and Issues
The "SeaWinds on ADEOS-II Scatterometer" mission was operational from April 10, 2003, to October 24, 2003 (when the ADEOS-II satellite lost power).
Wind Stress Curl Field Differences
as Derived from SeaWinds Systems aboard QuikSCAT and ADEOS-II
Presented By Jan Morzel and Ralph Milliff
at the SeaWinds/ADEOS-II Cal/Val Meeting ,
29 September 2003, Arcadia, CA.
Summary
-
Very high resolution wind stress curl fields are obtainable from SeaWinds systems aboard QuikSCAT and ADEOS-II. (see also, presentation by Chelton et al., this meeting).
-
Wind stress curl at high resolution is an important contributor to basin-scale ocean circulation.
-
Rainflags in SeaWinds retrievals occur disproportionately in cyclonic wind stress curls associated with synoptic systems, leading to biases in implied ocean transports (e.g. from zonal average wind stress curl).
(See also QSCAT rain effect on windstress curl and divergence.)
-
With the purpose of forcing high-resolution global and basin-scale ocean models in mind, a crude and agressive modification to rainflags in the standard wind retrieval products has been implemented on and interim basis. Rainflags are ignored for WVC with wind speeds &ge 15 m/s. We use the label "rain15" to identify wind and wind stress derivative datasets that employ this rainflag modification.
-
The rain15 datasets can be a dramatic improvement over standard products for forcing global and basin-scale models (e.g. hurricane fabian).
-
Differences between rain15 and "no rain" wind stress curl datasets for SWS on
QSCAT and ADEOS-II are not the same. Differences in the Southern Ocean (near the ice edge) are of opposite sign.
( At the meeting, it was discovered that these differences are due to different ice maks employed in the two datasets: QSCAT processing uses weekly ice maps, whereas the CAlVal ADEOS-II dataset employed daily ice masks. In order to keep both datasets as similar as possible, it was decided that the ADEOS-II data are going to be reprocessed with the same ice masks as in QSCAT. See figure ?? below for results from the reprocessing.)
-
It is important to the science community that wind stress curl climatologies from the two SWS differ as little as possible.
Click on the images for enlarged versions of plots.
Fig. 1. Three QSCAT swaths in North Pacific with (a) all rain-flagged (red) WVC omitted from QSCAT curl, and (b) all rain-flagged WVC with speeds &ge 15m/s (green "rain15") included.
Fig. 2. Wind stress curl derived from ADEOS-II (Apr-Sep 2003), (a) with all rain-flagged WVC excluded, and (b) rain15 WVC included.
Fig. 3. Curl difference (rain15 - no rain) for (a) ADEOS-II, and (b) QSCAT.
Fig. 4. Curl in North Atlantic during hurricane Fabian from ADEOS-II, (a) with all rain-flagged WVC excluded, and (b) rain15 WVC included.
Fig. 5. Zonal average of curl, Apr-Sep 2003, and difference (rain15 - no rain), for (a) QSCAT, (b) ADEOS-II CalVal data, and (c) ADEOS_II after CalVal.
Note, that Figure 5c was produced after the Cal/Val meeting, and after JPL reprocessed the SeaWinds on ADEOS-II data. The new data was reprocessed in October 2003 for the public release of the ADEOS-II data.
last modified on March 12, 2004
Go
Back
)
)
)
)
)
)
)
)
)
)
)