## UC Berkeley / Lawrence Berkeley Laboratory

#### Mathematical problems in radar wind data quality control and assimilation

**Qin Xu, National Severe Storms Laboratory, NOAA**

##### February 23rd, 2011 at 4PM–5PM in 939 Evans Hall [Map]

The NEXRAD radars have provided information on storm structure and other
atmospheric phenomena never before available to operational forecasters. The
radars can scan the atmosphere at high spatial and temporal resolutions, yet
the measurements are limited mainly to reflectivity and radial-velocity
component (along the radar beam) and the data are not free of quality problems.
Using radar observations to improve numerical weather predictions requires
major research efforts in radar data quality control and assimilation. Applied
mathematical problems encountered in the required research are often critical
but not completely solved. Three examples will be presented in this talk. The
first example involves a global minimization problem in which multiple local
minima are caused by the zigzag-discontinuities of modified observation
operator in the cost-function. The modified observation operator mimics the
aliasing effect in raw radial-velocity data. The second example presents the
methods developed for wind error covariance estimation and vector wind
estimation in our current real-time radar wind analysis system. The third
example shows the singular-value and spectral formulations derived for
measuring information content from observations and their applications to radar
data compression and radar scan optimization.