A Simple Doppler Wind Lidar Sensor: Simulated Measurements and Impacts in a Global Assimilation and Forecast System

We have simulated the wind measurements which might be obtained from a low power doppler wind lidar DWL sensor. Wind profiles obtained from such an instrument will not be as complete as those expected from planned higher energy sensors e.g.LAWS, with measurements only from cirrus clouds, the tops of other clouds, and from marine boundary layer aerosol. The potential impact of such a scaled down DWL system has been assessed by inserting the simulated measurements into the Air Force Phillips Laboratory Global Data Assimilation System GDAS. Results from the observing system simulation experiment OSSE indicate that significant improvement in the analysis and forecast of geopotential height, horizontal wind, and relative humidity may be expected in the southern hemisphere extratropics. Comparison of impacts with those obtained in a previously conducted OSSE which assumed a full blown DWL instrument WINDSAT indicate that the low energy lidar yields improvements which are 12 to 34 magnitude of improvements with WINDSAT. Thus, if the development cost of a simple lidar is found to be substantially less than a LAWS-type sensor, such an instrument may warrant consideration in the planning of future space-based observing systems.