An Aerosonde adaptive observing strategy for THORPEX

The Aerosonde is a small, robotic aircraft designed to undertake a wide range of operations in a highly flexible and inexpensive mode. The basic characteristics and details of recent operations can be obtained from www.aerosonde.com. The implementation of Aerosonde operations on a global basis is described in a separate paper by Gauntlett et al. Here we discuss the strategy for taking adaptive observations in support of THORPEX.

Current research indicates that the largest 72-hr synoptic-scale forecast errors over western and eastern North America during January and February of 1997-1999 can be traced to initial condition deficiencies (primarily, poor upper-air analyses of temperature and wind) over the North Pacific basin and arctic North America. The largest 96-hr forecast errors over western Europe during January and February 1999 were most sensitive to initial conditions over relatively data-sparse sections of Canada. The regions of major sensitivity are relatively local in nature. They can vary substantially from year to year, but have a consistency from one day to the next, making them attractive to adaptive observing strategies.

The primary aerosonde operations areas are seen to be in the region east of Japan, and between Hawaii/Midway and the US west coast. A preliminary examination of model-defined requirements indicated that Aerosondes could provide the enhanced observations required. Several OSSE studies are now being undertaken to determine the model response to a variety of Aerosonde deployment strategies and the results will be described in the presentation.