Tropical Cyclones

Overview

Tropical cyclones develop primarily in the summer months in regions with very warm sea surface temperatures, high low-level humidity and resulting instability that favors the development of thunderstorms, low amounts of vertical wind shear, and within the lower latitudes where these environments combine with a Coriolis force sufficient for establishing a surface area of lower pressure.  As they build in intensity, tropical waves and disturbances progress through categories of tropical depressions and named tropical storms, then to hurricanes and major hurricanes, the latter defined as a category three or higher on the Saffir-Simpson hurricane scale.  Tropical cyclones are readily observed in satellite imagery as organized clusters of thunderstorms in the lower tropical latitudes, and are much better known for the distinct, cloud-free eye common to major hurricanes as they move across the open oceans.  These cyclones bring large areas of damaging winds in addition to other threats from prolonged heavy rains and coastal inundation as a result of high storm surge, often requiring large evacuation zones when they threaten to impact populated areas, including the islands of the Pacific, southeastern Asia, and the Gulf Coast or eastern seaboard of the United States.

Tropical cyclones are frequently observed by NASA’s Global Precipitation Measurement (GPM) mission where their structure is made apparent through use of passive microwave brightness temperatures at various frequencies and polarizations.  In addition, their intense rainfall rates are readily mapped by the Integrated Multi-Satellite Retrievals for GPM (IMERG) product, and additional views of their three-dimensional structure made available through active radar scanning by the GPM core satellite.  Mapping of offshore heavy rain rates can provide responders with an expectation of what will occur after landfall, and improved identification of the storm’s center can aid tracking of the system and improved initialization with numerical weather prediction models.  Inland, rainfall estimates can be combined with streamflow and inundation models to understand flood risks resulting from the storm, and combined with topographical models and other information to characterize landslide threats.  Following landfall, flooding can be mapped using optical remote sensing from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua missions, the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the NASA/NOAA Suomi National Polar-orbiting Partnership (S-NPP) mission, or from the higher resolution views of the USGS/NASA Landsat-7 and Landsat-8 missions.  VIIRS also provides a unique opportunity to map power outages from space, which occur frequently as a result of landfalling tropical cyclones, and help to monitor the recovery of power in the days and weeks that follow.  Should post-storm cloudiness obscure a view of the land surface, synthetic aperture radar measurements of water extent from the European Space Agency’s Sentinel-1A and 1B platforms can assist with active scanning of inland surge and flood waters.  Finally, widespread damage to vegetation and treefall can be mapped over time from the aforementioned platforms, with ecosystem recovery monitored in the years that follow through consistent and continued imaging of the affected area

Latest Updates

April 4, 2017
Sentinel-1 flood map from Australia.
The NASA SPoRT team provided change detection products that highlight recent flood waters in Australia from Tropical Cyclone Debbie using Sentinel-1 data. These products were developed in conjunction with colleagues at the Alaska Satellite Facility (https://www.asf.alaska.edu/). The change detection is a simple algorithm is based detecting change that is consistent with flooding using a pre- and post-event scene. The product’s final form is...
March 29, 2017
Animated 3D look at precipitation from tropical cyclone Debbie.
Tropical cyclone Debbie formed in the Coral Sea northeast of Australia om March 24, 2017. Debbie intensified and had hurricane force wind speeds within a day of formation. While headed toward northeastern Australia Debbie reached it's maximum sustained wind speeds estimated at over 100 kts (115 mph) on March 27, 2017 (UTC). Tropical cyclone Debbie came ashore on March 28th and brought destructive winds and extremely heavy rain to northeastern Australia. It was reported that heavy rainfall caused flash flooding that cut off a coastal town and covered several roads in Queensland. ...
March 28, 2017
An inundation map of the region near Proserpine, Australia, produced using the Global Flood Monitoring System (GFMS) on 3/28/17.
An inundation map of the region near Proserpine, Australia, produced using the Global Flood Monitoring System (GFMS). The GFMS is a NASA-funded experimental system using real-time TRMM Multi-satellite Precipitation Analysis (TMPA) precipitation information as input to a quasi-global hydrological runoff and routing model.
October 12, 2016
IMERG total of hurricane matthew.
In this animation Hurricane Matthew travels up the east coast from Florida to the Carolinas. On October 8, 2016 Matthew (still a category 2 hurricane) dumps massive amounts of rain throughout the southeast dousing North and South Carolina. GPM then flies over the area revealing precipitation rates on the ground. As we zoom in closer, GPM's DPR sensor reveals a curtain of 3D rain rates within the massive weather system. To download:...
October 9, 2016
 On October 9, 2016, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image of floodwaters laden with sediment pouring out from several rivers in North Carolina and South Carolina.
Though its winds had weakened as it moved north, Hurricane Matthew delivered record-breaking rainfall to parts of Georgia, South Carolina, North Carolina, and Virginia. In many coastal areas, the storm dumped well over 12 inches (30 centimeters) of water. On October 9, 2016, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s ...

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