Improving convective trigger functions using GOAmazon observations

Description

In this work, we first evaluate the trigger functions of several commonly used convection schemes and then improve the better-performing ones using observations from the GOAmazon 2914/15 field campaign. Consistent with our earlier work using SGP and TWP-ICE data, the best-performing trigger functions are two dCAPE trigger functions (dilute and undilute), and Bechtold trigger function. In addition, a new trigger function (heated condensation framework, HCF) devised by Tawfik and Dirmeyer (2014) also performs well. To further improve the trigger functions, additional variables not used in the trigger functions are examined. We found that including vertical velocity information in the lower levels can improve the skill score of undilute dCAPE trigger and optimizing entrainment rate can improve the performance of dilute dCAPE trigger. On the other hand, the Bechtold trigger function can be improved by including information of vertical velocity in the upper levels. Improvement is also achieved with the HCF trigger function when including vertical velocity information in the mid-troposphere and optimizing the temperature deficit used in the trigger function. Convection in the Amazon region consists of different types of convective systems and exhibits clear diurnal variation. The performance of the trigger functions for different types of convective systems and over the diurnal cycle is thus also examined. The revised dilute dCAPE trigger performs best for different convection systems and for the diurnal cycle of convection.