Influence of environmental moisture on TRMM-derived tropical cyclone precipitation over land and ocean
Article
Jiang, H, Halverson, JB, Zipser, EJ. (2008). Influence of environmental moisture on TRMM-derived tropical cyclone precipitation over land and ocean
. GEOPHYSICAL RESEARCH LETTERS, 35(17), 10.1029/2008GL034658
Jiang, H, Halverson, JB, Zipser, EJ. (2008). Influence of environmental moisture on TRMM-derived tropical cyclone precipitation over land and ocean
. GEOPHYSICAL RESEARCH LETTERS, 35(17), 10.1029/2008GL034658
The rainfall climatology and persistence model (R-CLIPER) used operationally in the Atlantic Ocean basin mainly utilizes tropical cyclone (TC) intensity to predict TC rainfall. However, the rain production by TCs is also influenced by environmental parameters such as total moisture availability, horizontal moisture convergence, vertical wind shear, and sea surface temperature (SST). Previous TC case studies have used environmental moisture parameters to diagnose TC rainfall. In this study, we composite over 3000 snapshots of 3-hourly TRMM 3B42 rainfall fields for Atlantic landfalling tropical cyclones between 1998-2006 to analyze the rainfall distribution and storm total volumetric rain as a function of total precipitable water (TPW), horizontal moisture convergence (HMC), and ocean surface flux (OSF) over land and over ocean. For over ocean conditions, higher TPW, HMC, or OSF values are associated with higher azimuthally averaged rain rates. Over land, this is still the case but less obvious. Computing the linear correlation coefficients between total volumetric rain and moisture parameters shows this fact much more clearly. These coefficients are generally higher for over ocean conditions than those for over land conditions. To test if moisture parameters can provide additional information other than TC intensity to help TC rainfall forecasts, a multiple linear regression is performed between TC volumetric rain and several variables including TC maximum wind speed, TPW, HMC, and OSF. By adding moisture parameters as additional variables, TC volumetric rain will be better predicted than using TC intensity (maximum wind speed) only. The correlation coefficient between volumetric rain and maximum wind speed can increase from 0.52 (0.51) to 0.67 (0.65) for over ocean (land) conditions by adding TPW, HMC and OSF. By adding TPW only, the correlation coefficient increases to 0.59 and 0.64 for over ocean and land, respectively. Copyright 2008 by the American Geophysical Union.
