Recent simulation experiments by Smith and Glatz (1998) have investigated the spacing requirements of airborne dropwindsonde soundings for an accurate determination of the wind asymmetry in a hurricane. The calculations show, inter alia, that an increased number of soundings along a given flight pattern does not necessarily lead to an improvement in the accuracy of determination of the wind asymmetry. This is in contrast to an increased number over a regular grid. The reason is probably a result of insufficient over-sampling of the asymmetry to allow its resolution by a purely empirical interpolation between the observation points.
This paper explores an alternative approach for an irregular spacing of dropwindsondes. The idea is to fit an assumed asymmetric structure to the observations, the choice being guided by the structures that evolve in theoretical models. The scales of these structures are determined by a least-squares fit to the available data. Preliminary results indicate that the method is unsuccessful for data distributions typically achieved in Atlantic hurricanes and we are currently seeking to establish what data density would be required. The results will be presented at the Conference.
Reference
Smith, R. K., and A. Glatz, 1998: The detection of hurricane asymmetries from aircraft reconnaissance flight data: some simulation experiments. Quart. J. Roy. Meteor. Soc., (in press)