Verification of the improved predictive capability of a 1-D forced time-dependent cloud model with truncated hail spectrum

Abstract

A new 1-D forced time-dependent model version with the hail size spectrum which includes only hail sized particles (larger than 0.5 cm in diameter; hereafter called realistic hail spectrum) was tested against its version which treats the hail size spectrum from zero to infinity (hereafter called idealized hail spectrum). Comparisons between simulated cloud top heights by two model versions and the observed values were also performed. Our experiments were done for 45 routine midday soundings. The intermodel comparisons show that the realistic hail spectrum changes systematically the values of hail, rain and cloud ice maxima mixing ratios as well as those for vertical velocity, as compared to the idealized hail spectrum. The values of the model cloud-top heights with the realistic hail spectrum mainly overestimate their idealized values for clouds higher than 9 km. The modeled values of maximum cloud top heights given by the realistic hail spectrum are better correlated with observed values (r = 0.90) than those with the idealized one (r = 0.83). The model version with the new formula simulates some characteristics of the microphysical fields which are in fair agreement with observations. © by Gebrüder Borntraeger 1999.