Interactions between tropospheric chemistry and climate model temperature and humidity biases

Abstract

Temperature and humidity climatologies from the Met Office Hadley Centre climate model, HadGAM1, show a strong cold bias of up to 5 K in me extra-tropical upper troposphere/lower stratosphere and a dry bias of up to 20% in me tropical lower and mid troposphere. Removing the temperature bias alone has little effect on tropospheric ozone or methane lifetime. Removing me humidity bias alone causes a reduction in both me global annual mean tropospheric ozone burden of greater man 2% and the mediane lifetime of 3.6-4.2%. The impact of removing both biases together is similar to mat of removing the humidity bias alone. The choice of reanalysis product (ERA-40 or NCEP) to calculate the biases does not greatly affect die results. Radiative feedback from ozone and mediane reduced some of the climate model biases without any significant change to me performance of the chemistry. Copyright 2009 by the American Geophysical Union.