Km-Scale Simulations of Mesoscale Convective Systems (MCSs) Over South America -- A Feature Tracker Intercomparison

A. F. Prein, Zhe Feng, Thomas Fiolleau, Zachary Moon,

Kelly Núñez Ocasio, Julia Kukulies, Remy Roca,

Adam Varble, Amanda Rehbein

SAAG Meeting

June 14, 2023

This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under Cooperative Agreement No. 1852977.

What we do

• We run an ensemble of MCS trackers on the three test simulation years 2010/11, 2015/16, and 2018/19.

​

• We run the trackers on the WRF SAAG 4 km simulation output and GPM derived hourly precipitation and brightness temperature.

​

• We use four criteria to classify what an MCS is.

​

• We want to understand how the tracker selection effects MCS statistics and the evaluation of the SAAG simulation.

MCS trackers differ in their initial identification of MCSs, when they end MCS tracks, and particularly how they handle merging and splitting of storms.

MCS trackers differ in their initial identification of MCSs, when they end MCS tracks, and particularly how they handle merging and splitting of storms.

While the Annual Cycle of MCS Frequencies is Similar in all Trackers Their Amounts can Vary by a Factor of Three and Model Performance is Difficult to Assess

The Tracker Selection can Have a Strong Impact on MCS Characteristics Although the Model Evaluation is Less Affected

The Tracker Selection can Have a Strong Impact on MCS Characteristics Although the Model Evaluation is Less Affected

GPM-IMERG underestimates peak hourly rainfall rates and overestimates rainfall frequencies.

MCS Initiation Frequencies Vary Largely Between Trackers and Strong Variations of Model Performance are Seen

The Ratio of MCS Precipitation can Vary Largely Between Tracking Systems but Model Evaluation Results are Similar