Publication Date:
2016-12-17
Description:
Observing System Experiments have been used to evaluate the forecast impact of sea level pressure observations from drifting buoys. Two seasons have been selected with different synoptic weather characteristics, but similar amount of buoy observations. Control and denial experiments were performed with and without assimilating drifting buoys sea level pressure observations. The denial experiments withdraw around 95% of the total surface pressure measurements from buoys; the remnant 5% is provided by moored buoys. Changes in the forecast performance are evaluated in terms of root mean-squared error and anomaly correlation scores. Adjoint diagnostic tools are also used to estimate the observations contribution to the analysis and forecast. The lack of drifter surface pressure observations has large and significant detrimental impact on the mean sea level pressure, temperature and wind fields. The signal is detectable not only near to the surface but throughout the troposphere up to 250 hPa. Drifter surface pressure observations contribute to decrease the total global forecast error by approximately 3%. In particular, case studies reveal that drifting buoy observations can be especially important to reduce the forecast error on complex or rapidly evolving cyclogenesis. All the diagnostics performed indicate that drifting buoys are essential ingredients of WMO’s Global Observing System.
Print ISSN:
0035-9009
Electronic ISSN:
1477-870X
Topics:
Geography
,
Physics
