Verification of short-term forecasts from the Navy COAMPS over the Mediterranean

A one-year series of 24-hour forecasts was generated at 12-hour intervals over the Mediterranean Sea region for the period from 30 September 1998 – 30 September 1999 using the Navy COAMPS model. The control simulation consisted of two nested grids with 30 vertical levels and horizontal spacings of 81 and 27 km, respectively. The inner grid covered most of Europe and northern Africa between the latitudes of 30° and 50° north and longitudes of 15° west and 40° east. Model data were interpolated to the upper air station locations, and RMS and bias statistics were calculated for the momentum, temperature and relative humidity fields. Daily, monthly, and yearly grid-averaged statistics were generated to view the progression of model errors through height and time. Statistics were sorted based on wind speed, precipitation, surface pressure, and cloud cover thresholds to determine sensitivities to weather regime. A series of sensitivity studies was also conducted with varying model domain sizes, horizontal and vertical grid resolutions, and initialization methods to determine the effects of these changes on the forecasts. The results will be discussed in terms of the improvement of forecast value and its relation to the output statistics.