CASA is developing a revolutionary new paradigm of using a network of small, closely spaced, inexpensive, low-power dual-polarization Doppler weather radars to overcome the inability of widely spaced, high-power radars to sample large regions of the lower atmosphere owing to the curvature of earth given that zero or negative beam elevation angles are not allowed. Driven in large part by this need, but also by the goal of using numerical models to explicitly predict intense local weather such as thunderstorms, the National Science Foundation established, in fall 2003, the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). To improve lead time and the probability of detecting tornadoes while decreasing the false alarm ratio, a greater understanding, obtained in part by more complete observations, is needed about the region of storms within which tornadoes form and persist. Increasing tornado and severe storm warning lead time (lead time is defined here as the elapsed time between the issuance of a watch or warning and the time at which the anticipated weather event first impacts the specified region) through the use of radar observations has long been a challenge for researchers and operational forecasters. The RMS represents a root-mean-square difference between pseudo-observed Doppler velocity data points and the retrieved data points using (A9) in azimuthal and range directions. The thick curve indicates the profile of the retrieved tangential velocity ( V RET) data. The data points (black large dots) indicate the locations of successive Doppler velocity measurements ( V d) collected at azimuthal sampling increments as the radar beam scans across the vortex when one data point is coincident with the vortex center. The dashed line represents the model profile V 12 the solid black line represents the pseudo-observation profile ( V 1), the thick line on which the data points fall is the Doppler velocity ( V d) azimuthal profile of the signature.
![tornado simulator v.3 alpha tornado simulator v.3 alpha](https://i.pinimg.com/originals/c0/ac/a1/c0aca1654b0252cc1f0fd172097e6ae4.jpg)
The shaded region indicates the core diameter of the vortex. Relationships of data points relative to the azimuthal profiles of a Doppler velocity signature at a range of 15 km for azimuthal sampling intervals (ΔAZ) of (top) 2.0° and (bottom) 1.0° for a beamwidth of 2° and a vortex having a core radius of 0.1 km.