The Challenges of Assessing the Future Impact of Space-based Doppler Wind Lidars While Using Today’s Global and Regional Atmospheric Models

Global measurement of tropospheric wind has been widely recognized as potentially the most significant contribution of satellite remote sensing to existing global meteorological observations. Most of the world's oceans are largely devoid of accurate wind measurements, a deficiency that can best be addressed from space. The deployment of a space-based Doppler Wind Lidar would provide the capability to address many of the key issues such as hydrologic and biogeochemical cycles, planetary scale dynamics, atmospheric-oceanic heat transport. Equally important, it would provide critical wind information for improved operational weather forecasting, and for safe, efficient, and effective military and commercial aviation operations.

Ground-based and airborne-based lidars have demonstrated the ability to make direct measurements of horizontal winds based on determination of the wind-induced Doppler shift in the backscatter signal. However, space-based application of Doppler Wind Lidar technology is without heritage, thus, optimal design of DWL systems for space deployment must rely upon computer model studies. These model studies include efforts with DWL performance models, atmospheric circulation models and atmospheric optical models. Once a candidate(s) DWL concept is chosen for an impact study, a full Observing System Simulation Experiment (OSSE) is conducted and evaluated.

To develop an optimal design concept for space-based lidar platforms, a DWL simulation model (LSM) has been developed to address questions of optimum laser wavelength, pulse length, minimum power, scanning strategies, optimal signal processing and wind computation algorithms. The LSM simulates space-based/airborne coherent and incoherent Doppler lidar wind sounders, producing simulated Doppler lidar winds using either global (ECMWF T213 and T106) or mesoscale (29 km Eta and CSU RAMS) atmospheric model fields as inputs. The LSM’s atmospheric algorithm library, coupled with atmospheric model fields, provides opaque clouds, cirrus clouds, cloud optical properties, aerosol backscatter, molecular attenuation, atmospheric turbulence and terrain information that must be considered when modeling a space-based DWL. This paper discusses the benefits and limitations of using today’s model atmospheres in a simulation model to access a future space-based DWL system.