Longitudinal variability of the width of the tropical belt
Tuesday, July 28, 2015
Thomas Birner, CO State Univ-Atmospheric Sci, Fort Collins, CO, United States, Bryce Currey, Loyola Marymount University, Los Angeles, CA, United States and Nicholas Davis, Colorado State University, Fort Collins, CO, United States
Abstract:
Most past studies on the tropical belt width have focused on its zonal mean characteristics. Here we present an analysis of longitudinal variations in the tropical belt edge latitudes. These edge latitudes are defined based on the subtropical tropopause break, which marks the typically sharp transition from the high and cold tropical tropopause to the much lower and warmer mid-latitude tropopause. Results based on monthly mean temperature data are compared between reanalyses and GPS radio occulatations. We find the tropopause break metric to be generally well defined and suited for this type of analysis. Notable exceptions exist in particular near the jet exit regions over the ocean basins during each hemisphere's summer where strong interannual variations of the edge latitudes are observed. Overall, poleward excursions of the tropical edge latitudes are found near the jet entrance regions with equatorward excursions near the jet exit regions. Relationships between the edge latitudes in both hemispheres and interannual variability due to climate variability such as ENSO are analyzed.
