A 5-day hindcast experiment using a cut cell z-coordinate model

Abstract

We investigate the use of the cut cell vertical discretisation for forecasts of 5 days. To obtain an indication of the usefulness of this new method a 5-day forecast over the area of India is investigated. So far the cut cell model LMZ was tested extensively for 1 day forecasts on a European area. Following indications of a reduced temperature error for the short forecasts, this paper investigates the model error for a 5-day forecast in an area of strong orography. The forecast indicated a strong reduction of the temperature error. After 5 days the temperature error is smaller or equal for the cut cell model nearly everywhere, when compared to the terrain following control model. Over large areas the temperature error improved by 5-10°. Other features observed in the 1-day forecast were present also in the 5-day forecast. These were a substantially improved precipitation forecast and very differently forecast vertical velocities. © 2011 Royal Meteorological Society.