Drifting buoy pressures: Impact on NWP

Abstract

This study was conducted to assess the impact on NWP and to provide guidance on drifting buoy observation density, with particular attention to the North Atlantic. The impact of halving the buoy density was studied using observing system experiments; as expected half the density has more than half the impact, but there is still scope for improvement with a higher density of observations. For drifting buoy pressure data, both large observation-minus-background differences and large forecast sensitivity tend to be in synoptically active, cyclogenesis regions. It is noted that almost half of drifting buoys do not have a pressure sensor—this is regrettable given the importance of pressure data in remote oceanic areas.