Data Requirements for Doppler Lidar Measurements of Winds from Space

An important input to the design of space-based measurement systems is the data requirements which are typically defined in terms of the bias and random error of the measurement for various spatial and temporal sampling conditions. Thedominant driver for space-based wind measurements is Numerical Weather Prediction (NWP) models. Since many types of dataare used in operational NWP, the data requirements for all measurements must be defined in a consistent manner to correctly determine the value of each measurement technology in terms of total measurement error and the improvement in the initial state of the atmosphere (data assimilation). The total measurement error consists of the instrument error and the observation sampling error (related to the error of representativeness) which defines the mismatch between the observation sampling pattern and the spatial sampling of the desired measurement or "truth". To produce a consistent definition of observation error and forecast error, the spatial average for "truth" is defined as the effective resolution of the NWP model. The resulting implications for Doppler lidar data requirements is presented.