NUMERICAL SIMULATION OF INFLUENCE OF STRATOSPHERIC METHANE ON TROPICAL WATER VAPOR AND TEMPERATURE

Abstract:

Climatic characteristics of tropical stratospheric methane have been well researched using various satellite data, and numerical simulations have furtherly conducted using chemical climatic models, while the impact of tropica1 stratospheric methane oxidation on tropical distribution of water vapor is not paid enough attention in general circulation models. Parameterization of methane oxidation is taken into account to deal with the chemical moisturizing action due to the methane oxidation in this paper. Numerical simulation and analysis of the influence of stratospheric methane on the prediction of tropical stratospheric moisture and temperature fields using general circulation model is conducted using heavy storm cases including a heavy rain in South China and a typhoon caused tropical storm. The results show obvious impact of methane oxidation on the forecasting precipitation. It is demonstrated that the stratospheric water vapor in the tropic is significantly remedied by introducing of parameterization of methane oxidation. And prediction of stratospheric temperature is accordingly modified, especially in the lower stratosphere within 30oN. The verification of monthly mean of forecast anomaly correlation (ACC) and root mean square (RMS) errors over the tropics indicated that the impact of stratospheric methane is neutral as to the forecast of geopotential height, and positive to the forecast of temperature and winds over the tropics.