Extreme Weather: Monitoring Severe Storms From Space

There are a number of indications that, as the climate changes, there will be more frequent and more intense severe storms, which includes tropical cyclones, mesoscale convective systems, and extratropical cyclones. Many aspects of these storms are poorly understood, modeled and predicted, and there is a dire need for better observations. In this presentation we examine some of the options for improved observing systems, with an emphasis on satellites but also with consideration given to suborbital and ground systems. Since severe storms generally evolve and propagate quite rapidly, conventional polar-orbiting weather satellites are inadequate, providing only brief snapshots twice a day at best and often less. Even with a number of such satellites in different orbit planes it is difficult to achieve the rapid updates that are necessary to fully observe and characterize the dynamics and internal processes of the storms. Geostationary satellites observe a large portion of the globe continuously with very rapid updates, but current sensors operate only in the visible or infrared spectrum, which does not allow penetration of clouds and precipitation and therefore only sense the cloud tops and the areas surrounding the storms. Instead, it is necessary to have sensors that operate in the microwave spectrum, such as passive radiometers and active radars. Until recently, the large antenna aperture required for a geostationary microwave sensor has been a prohibitive barrier, but the Jet Propulsion Laboratory has now developed the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR), under the NASA Earth Science Technology Office's Instrument Incubator Program, that overcomes this obstacle. The GeoSTAR concept was the basis for the Precipitation and All-weather Temperature and Humidity (PATH) mission recommended by the National Research Council in its 2007 Decadal Survey of earth science from space. A demonstration mission implementing a substantial subset of PATH – GeoStorm – has been proposed as a low-cost hosted mission under NASA's Venture (EV-I) program. We will discuss the objectives of these missions and the measurements they will produce, the science investigations they will enable and the storm science progress that can be expected. We will also discuss an alternative that has recently been proposed – a constellation of low-earth-orbiting cubesats that may be able to achieve similar temporal sampling at a relative low cost, and we will discuss aspects of each approach.

Copyright 2013 California Institute of Technology. Government sponsorship acknowledged.