SMAP Version 1 Winds New Release
SMAP V1 wind has been released and is available here
SMAP V1 replaces the experimental Beta version (V0.1), which was released in July 2016:
The new Version 1 includes several upgrades:
- New Radiative Transfer Model (RTM), which is the same as used for Aquarius V5 salinity product. In particular, the wind-induced emissivity has now a slight dependency on Sea Surface Temperature (SST).
- Improved calibration for winds above gale-force (17 m/s)
- Improved land and sea-ice masking.
- Processing and distribution of two separate products:
- A Near-Real Time (NRT) Wind speed, as soon as Level-1 data becomes available from the NASA Snow and Ice Data Center (NSIDC). The NRT wind processing uses ancillary fields of shorter latency but lower quality (i.e., salinity, SST, and atmospheric profiles from forecast models)
- A Final Wind Speed version, reprocessed with a 1-month delay, which uses higher quality ancillary data.
- The Final wind product uses observed 8-day averaged SMAP salinity processed at Remote Sensing Systems, whereas the NRT product use a salinity forecast field from the HYCOM model.
The following figures display the global maps for V0.1 and V1.0 winds. Notice differences due to changes in land and sea-ice mask, and improved winds in the river outflow
- Tropical Cyclone fixes: ASCII files with SMAP V1 observed maximum 10-min sustained wind speed and radii for 34 kn (17 m/s), 50 kn (25 m/s) and hurricane force 64 kn (33 m/s wind speed) for each quadrant in TC are provided in Near-Real Time. This data, commonly referred as fixes is provided in nautical units for tropical storm forecasting, in the same format as used by the Automated Tropical Cyclone Forecasting (ATCF) system . The TC fixes are available here
- TC Images: contour plots of wind field and storm radii for each SMAP pass over tropical cyclones are provided as jpeg files for all tropical basins (Atlantic, Pacific, Indian, and Southern hemisphere). Images are available on the RSS FTP. Displayed here is the image for hurricane Irma on September 5, 2017.
Impact of V1 release on Wind SpeedsSeveral known issues have been resolved in the V1 winds:
- In the NRT product, river-plumes which are prone to errors due to high salinity variability are masked out. They are included in the final product as they are higher quality than NRT. Spurious biases in the V0.1 winds speeds in river plumes are now corrected in the V1.0 speeds by using SMAP salinity fields in processing the SMAP Final winds.
- In Extra-Tropical cyclones in cold waters, SMAP V1 winds are approximately 6% lower than SMAP V0.1 (Beta version) at high wind speeds (above 25 m/s).
- In Tropical cyclones there is only a very small reduction at high wind speeds in V1 compared to the Beta version.