Sensitivity of quantitative precipitation forecast to height dependent changes in humidity
Article first published online: 14 MAY 2008
Copyright 2008 by the American Geophysical Union.
Geophysical Research Letters
Volume 35, Issue 9, May 2008
How to Cite
2008), Sensitivity of quantitative precipitation forecast to height dependent changes in humidity, Geophys. Res. Lett., 35, L09812, doi:10.1029/2008GL033657., , , and (
- Issue published online: 14 MAY 2008
- Article first published online: 14 MAY 2008
- Manuscript Accepted: 11 APR 2008
- Manuscript Received: 15 FEB 2008
- mesoscale modeling;
- humidity variation
 The impact of humidity variations on QPF is studied performing a series of sensitivity experiments with the COSMO model at a horizontal mesh size of 7 km. Generally, variations of humidity in the boundary layer have the largest impact on precipitation, and the sensitivity decreases with height. An increase of humidity by 10% in the boundary layer is equivalent to an increase of 20% in the mid-troposphere. While the impact of humidity variation on stratiform precipitation persists throughout the 36-h forecast period, the impact diminishes after 24 h in the convective rainfall area. Increasing the boundary layer humidity by 30% leads to a 6 h earlier initiation of convection and a five times larger precipitation amount in the convective area, whereas it is doubled in the stratiform region. These results indicate that accurate measurements of humidity in the boundary layer are most important for QPF.