We create displays of satellite-based surface wind measurements in tropical cyclones. These images are currently focusing on scatterometer (one technology for measuring surface wind) images.
When there is at least one active tropical cyclone of at least tropical depression strength (invests are not currently supported), new plots will be generated every three hours if scatterometer data are available (close enough to the storm) and added to our 'Active Storms' page. This page will display the nine most recent plots for each storm, with older plots being accessible in the 'All Storms' page. Once a storm is no longer active, all plots for the storm will be available on the ‘All Storms’ page. All plot images are downloadable from either page.
To create each plot, data on the tropical cyclone is pulled from TCVitals, which is a database that provides estimates of a storm’s center latitude and longitude, maximum wind speed, pressure, and other information. More information about TCVitals can be accessed here.
A new TCVital file is produced by the National Hurricane Center (NHC)* and Joint Typhoon Warning Center (JTWC)** every six hours at 2:41, 8:41, 14:41, and 20:41 UTC, intended for the 00Z, 06Z, 12Z, and 18Z synoptic times respectively. The size of each plot is 1,200 km by 1,200 km, created by adding 600 km to each side of TCVitals’ given latitude and longitude of the storm center. Each plot must have at least 50 wind barbs (or scatterometer wind observations). Wind speed contours (or isotachs) are added to areas at or above 34 knots, 50 knots and 64 knots. The table below lists what times plots are created in UTC, EDT, and EST.
* Provides data for the North Atlantic, East Pacific, and Central Pacific basins
** Provides data for the West Pacific, South Pacific, North Indian, and South Indian basins
| UTC | EDT | EST |
|---|---|---|
| 0:00 | 8:00 PM | 7:00 PM |
| 3:00 | 11:00 PM | 10:00 PM |
| 6:00 | 2:00 AM | 1:00 AM |
| 9:00 | 5:00 AM | 4:00 AM |
| 12:00 | 8:00 AM | 7:00 AM |
| 15:00 | 11:00 AM | 10:00 AM |
| 18:00 | 2:00 PM | 1:00 PM |
| 21:00 | 5:00 PM | 4:00 PM |
The plots featured here use data from six active satellites provided by National Aeronautic and Space Administration (NASA) / Jet Propulsion Laboratory (JPL) and Royal Netherlands Meteorological Institute (KNMI), of which five are currently transmitting data regularly:
- ASCAT-B 12.5km/Coastal (MetOp-B)
- Launched: 09/17/12
- Data availability: 10/29/12 to present
- ASCAT-C 12.5km/Coastal (MetOp-C)
- Launched: 11/07/18
- Data availability: 10/22/19 to present
- HY-2B 25km (Haiyang-2B)
- Launched: 10/28/18
- Data availability: 11/04/21 to present
- HY-2C 25km (Haiyang-2C)
- Launched: 09/21/20
- Data availability: 11/04/21 to present
- HY-2D 25km (Haiyang-2D)
- Launched: 05/19/21
- Data availability: 11/08/23 to 11/03/24
- OSCAT-3 25km (Oceansat-3)
- Launched: 11/26/22
- Data availability: 10/30/24 to present
The daily simplified NetCDF files for these scatterometers can be accessed here. Currently, ASCAT-A, ASCAT-B, QuikScat, and RapidScat are supported, with more planned in the future.
About the winds:
The wind speeds are mean winds rather than gusts. They are calibrated to the standard height of 10 m above the surface. Scatterometers are calibrated to measure equivalent neutral winds (the wind speed that when used in a bulk flux paramerization results in the correct stres when the atmosphere is assumed to be neutrally buoyant). This is subtly different from wind, but for strong winds the differences from what we would normally think of as winds are usually much less than 0.5 ms-1.
