Extreme Convection in the Equatorial Zone as Seen by 16 Years of TRMM PR M. D. Zuluaga and R. A. Houze, Jr. University of Washington PMM Science Team Meeting, Baltimore, 7 August 2014

Use TRMM to find the most pronounced convective & stratiform elements Identify every contiguous 3D echo object (“storm”) seen by PR Convective component Stratiform component Extreme characteristic Contiguous 3D volume of convective echo > 40 dBZ Top height > 10 km “Deep convective core” Horizontal area > 1 000 km2 “Wide convective core” Contiguous stratiform echo with horizontal area > 50 000 km2 “Broad stratiform region”

Diurnal Behavior in Each Subregion

DCC WCC BSR Land Coastal Open ocean

Synoptic Scale Environments (ERA-I)

Africa 700 hPa anomaly fields: Geopotential height Wind vectors

Coast of Tropical America 850 hPa anomalies

Orographic Enhancement over Andes Anomalies of divergence and specific humidity Andes Div. Orographic Enhancement over Andes

East Pacific ITCZ

Storms with BSR associated with Tropical Cyclone (TC) development in the East Pacific Tropical disturbance trajectory* Storms with BSR Storms with BSR associated to a TCs *database: Northeast and North Central Pacific hurricane best-track data (HURDAT2, NHC) ~30% of storms

Summary: Behavior of extreme convective metrics in the near equatorial region Diurnal Strongest for DCCs over land Sequence consistent with upscale growth: DCCWCCBSR Orographic Powerful enhancement of WCC & BSR by flow over Andes Synoptic Prominent for mesoscale organized features: WCC & BSR Maxima of WCC and BSR associated with lows at 850-700 hPa BSR over oceans max in regions of TC genesis

End This research was supported by: NASA grants NNX13AG71G, NNX12AJ82G, NNX10AH70G DOE grant DE-SC0008452 NSF grants AGS1059611, AGS1144105 and AGS1355567

ITCZ intersects two landmasses of differing characteristics

DCC BSR WCC

Summary: Behavior of extreme convective metrics in the near equatorial region DCCs mark the early stage of MCS 40 dBZ over land, 30 dBZ over ocean strongly diurnally forced—especially over mountains WCCs aggregated intense convection—in maturing MCSs occur over both land and sea occur later in day than DCC associated with 700 hPa synoptic-scale cyclonic flow enhanced by orographic lifting BSRs occur in late stages of MCSs mostly oceanic—near west coasts diurnal variability is slight but max later than WCC associated with TC development over oceans west of Africa and SA

Association of echo types with convection metrics Deep & Wide Deep conv. Wide conv. Broad Str.