Four years of ERA-40 vorticity maxima tracks

This study attempts to distinguish between developing and nondeveloping tropical disturbances using reanalysis data and satellite data. This is the first time many developing and nondeveloping disturbances have been compared on a consistent basis using both large-scale environment information and data from geostationary satellites and the Tropical Rainfall Measurement Mission (TRMM).;The climatology of VM tracks agrees with previous knowledge of tropical wave disturbances and hurricane precursors in the Atlantic and EPAC. Genesis productivity, defined as the fraction of noncyclone VM that eventually develop, reaches a maximum of 30% in the Atlantic and 50% in the EPAC.;Significant differences between developing and nondeveloping VM are found with respect to large-scale predictors and satellite-derived predictors (area of cold cloud tops and rainfall). Surprisingly, vertical shear is stronger for developing VM in the EPAC.;For the EPAC, the satellite-derived predictors give greater discrimination than in the Atlantic. Also, incorporating the satellite-derived predictors in linear discriminant analysis increases the discrimination in the EPAC but not in the Atlantic. Linear discriminant analysis is used to quantify the relative importance of the individual predictors and to make comparisons with previous studies.;Vorticity maxima (VM) are identified on Hovmdller plots of time filtered and smoothed relative vorticity. VM have been tracked manually for June-October, 1998--2001 in the Atlantic and eastern North Pacific (EPAC). Midlevel and low-level VM are tracked independently. The VM are classified as developing or nondeveloping based on whether they can be traced to a storm in the National Hurricane Center best track database.;Finally, for a limited subset of cases with coverage from the TRMM precipitation radar, the properties of precipitation features (PFs) associated with developing and nondeveloping disturbances are compared. The most significant difference between developing and nondeveloping PFs is that the developing PFs are much larger than the nondeveloping PFs. The greater area for developing PFs is associated with greater volumetric rain and latent heating.;The influence of the large-scale environment on genesis is probabilistic not deterministic. Genesis occurs under a range of environment conditions, and there is large overlap with the typical environment conditions of nondeveloping disturbances.