Convective variability in the North American Monsoon using cloud-to-ground lightning data and high-resolution satellite precipitation data
Abstract
This study examines diurnal to intraseasonal variability in lightning characteristics of the North American Monsoon using 5 years (2004-2008) of Vaisala's Long Range Lightning Detection Network (LLDN). The high-time and space resolution, as well as the continuous observation record of NALDN lightning data allows an unprecedented depiction of the diurnal cycle of cloud-to-ground lightning flash rates, and illustrates the coupling with topography and evolution of storms producing lightning in the North American Monsoon. Along with the LLDN data, this study will also examine high-resolution satellite precipitation data from NOAA’s Climate Prediction Center Morphing (CMORPH) rainfall estimates and echo vertical structure from the Tropical Rainfall Measuring Mission precipitation radar (PR) to examine variations in lightning-rainfall relationships and climatological radar echo vertical structure to infer the characteristics of convective systems. Results indicate that the relatively shallow convection observed in the high peaks of the Sierra Madre Occidental is accompanied very early on in the convective diurnal cycle by copious lightning. Despite the convection being relatively shallow according to infrared cloud tops and PR echo top heights, the lightning activity indicates that precipitation, produced largely from isolated convective systems, is mixed-phase in nature from nearly its start around noon. This relatively shallow, isolated convection in high terrain also produces the lowest rainfall to lightning ratios observed in the convective diurnal cycle over the core monsoon region, where rainfall-lightning ratios increase later in the afternoon and evening with the production of stratiform rain associated with mature mesoscale convective systems. The study will also examine the influence of synoptic (e.g., tropical easterly waves), intraseasonal (e.g., the Madden-Julian Oscillation), and interannual variations in lightning and rainfall characteristics to understand how the diurnal cycle of convective systems and lightning activity is modulated on key time scales upon which the North American Monsoon is known to vary.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.H41K..06N
- Keywords:
-
- 1855 HYDROLOGY / Remote sensing;
- 3314 ATMOSPHERIC PROCESSES / Convective processes;
- 3324 ATMOSPHERIC PROCESSES / Lightning;
- 3354 ATMOSPHERIC PROCESSES / Precipitation