Intraseasonal Variability of Mesoscale Convective Systems over the

Intraseasonal Variability of Mesoscale Convective Systems over the South Asian Monsoon Region Katrina Virts and Robert A. Houze, Jr. University of Washington

Identifying MCSs using A-Train data Yuan and Houze (2010)

Data sources • MCS database (2007 -2010) – Small separated MCSs – Large separated MCSs – Connected MCSs • Cloud. Sat – Vertical structure of precipitating and anvil regions • World-Wide Lightning Location Network – Monitors very low frequency (VLF) waves – MCS lightning frequency: lightning in one-hour window within MCS cloudy area • ERA-Interim reanalysis

Meghalaya Plateau NE Himalayan notch Bay of Bengal

30 -60 day 925 -h. Pa wind, height anomalies Based on BSISO 1 index by Lee et al. (2013)

30 -60 day 925 -h. Pa wind, height anomalies Based on BSISO 1 index by Lee et al. (2013) “Active”

CMCS Large SMCS Bay of Bengal 925 -h. Pa anomalies

Bay of Bengal

Meghalaya Plateau 850 -h. Pa anomalies

Meghalaya Plateau

NE Himalayan notch 850 -h. Pa anomalies CAPE anomalies

Conclusions • MCS occurrence and characteristics exhibit intraseasonal variations during the South Asian monsoon • Locally rainy period: large and connected MCSs with mature stratiform areas; decreased lightning production • Locally dry period: stronger convective signatures and more lightning production • Regional dependence of monsoon effect on MCSs This work was funded by NASA grants NNX 13 AQ 37 G, NNX 13 AG 71 G, and NNX 16 AD 75 G