Transcript PowerPoint Presentation - University of Washington

Extreme Convection in the
Equatorial Zone as Seen by 16
Years of TRMM PR
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
Extreme characteristic
Contiguous 3D volume of
convective echo > 40 dBZ
Contiguous stratiform echo
with horizontal area > 50 000 km2
“Broad stratiform region”
Top height > 10 km
“Deep convective core”
Horizontal area > 1 000 km2
“Wide convective core”
Diurnal Behavior in Each Subregion
BSR
DCC
WCC
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
Anomalies of divergence and specific humidity
Div.
Orographic
Enhancement over
Andes
Andes
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
WCCsaggregated 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.