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Synoptic, Topographic, and Diurnal Effects Synoptic, Topographic, and Diurnal Effects on Summer Convection in South Americaon Summer Convection in South America
Ulrike RomatschkeUlrike RomatschkeUniversity of Washington, University of Vienna
Robert A. Houze Jr., Socorro Medina, Kristen Rasmussen Robert A. Houze Jr., Socorro Medina, Kristen Rasmussen University of Washington
ICAM, Rastatt, Germany, May 15, 2009
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Sponsored in part by:
NSF Award# ATM-0505739
NSF Award# ATM-0820586
NASA Award# NNX07AD59G
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
ObjectivesInvestigate Distribution of convection
Find regions ofmaximum convective intensitymaximum precipitation
Forcing of convection bySynoptic conditionsTopographyDiurnal heating
Connection with precipitation climatology
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
DataData
Tropical Rainfall Measuring Mission Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR)Precipitation Radar (TRMM PR) 3D reflectivity3D reflectivity
10 years (December 1998 – February 2008)10 years (December 1998 – February 2008) Summer months: December, January, FebruarySummer months: December, January, February
NCEP reanalysisNCEP reanalysis Large-scale environmentLarge-scale environment
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Classification of radar echo structures Classification of radar echo structures within convective systems within convective systems
Deep Convective CoresDeep Convective CoresContiguous convective echo Contiguous convective echo ≥ ≥ 40 dBZ and 40 dBZ and ≥≥ 10 km in 10 km in
heightheight
Wide Convective CoresWide Convective CoresContiguous convective echo Contiguous convective echo ≥ 4≥ 40 dBZ and 0 dBZ and ≥≥ 1000 km 1000 km² ²
in areain area
Broad Stratiform RegionsBroad Stratiform RegionsContiguous stratiform echo Contiguous stratiform echo ≥≥ 50 000 km 50 000 km² in area² in area
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Distribution of radar echo structures
Deep Deep convectivconvective corese cores
Broad Broad stratiform stratiform regionsregions
Wide Wide convective convective
corescores
Precip. Precip. climatologyclimatology
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Regions of interest
Foothills Foothills NorthNorth
La Plata La Plata BasinBasin
Foothills Foothills South South
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Synoptic forcingSynoptic forcing
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
500 mb geopotential height anomaly500 mb geopotential height anomaly Surface pressure anomalySurface pressure anomaly
Composites, wide convective cores, La Plata BasinComposites, wide convective cores, La Plata Basin
Surface winds (~02 LT)Surface winds (~02 LT)
Foothills South, La Plata Basin
[mb][mb]
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
500 mb geopotential height anomaly500 mb geopotential height anomaly Surface pressure anomalySurface pressure anomaly
Composites, wide convective cores, Foothills NorthComposites, wide convective cores, Foothills North
Surface winds (02 LT)Surface winds (02 LT)
Foothills North
[mb][mb]
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Diurnal and Topographic Diurnal and Topographic forcingforcing
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Foothills South, La Plata BasinDeep convective cores
Wide convective cores
Broad stratiform regions
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Foothills North
Wide convective
cores
Broad stratiform regions
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Deep Convective cores
06 UTC 06 UTC ~02 LT~02 LT
00 UTC 00 UTC ~20 LT~20 LT
18 UTC 18 UTC ~14 LT~14 LT
12 UTC 12 UTC ~08 LT~08 LT
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Wide convective cores
06 UTC 06 UTC ~02 LT~02 LT
00 UTC 00 UTC ~20 LT~20 LT
18 UTC 18 UTC ~14 LT~14 LT
12 UTC 12 UTC ~08 LT~08 LT
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Broad stratiform regions
06 UTC 06 UTC ~02 LT~02 LT
00 UTC 00 UTC ~20 LT~20 LT
18 UTC 18 UTC ~14 LT~14 LT
12 UTC 12 UTC ~08 LT~08 LT
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Foothills South, La Plata Basin
06 UTC 06 UTC ~02 LT~02 LT
00 UTC 00 UTC ~20 LT~20 LT
18 UTC 18 UTC ~14 LT~14 LT
12 UTC 12 UTC ~08 LT~08 LT
10 m s10 m s-1-1
Composite winds and divergence, wide convective cores, La Plata BasinComposite winds and divergence, wide convective cores, La Plata Basin
DivergenceDivergence
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Foothills North
06 UTC 06 UTC ~02 LT~02 LT
00 UTC 00 UTC ~20 LT~20 LT
18 UTC 18 UTC ~14 LT~14 LT
12 UTC 12 UTC ~08 LT~08 LT
10 m s10 m s-1-1
Composite winds and divergence, wide convective coresComposite winds and divergence, wide convective cores
DivergenceDivergence
Ulrike RomatschkeUlrike Romatschke, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009, University of Washington, University of Vienna, ICAM, Rastatt, Germany, May 15, 2009
Conclusions
Synoptic low location criticalMoisture transport by low-level jet from tropics to
subtropics Diurnal heating
Daytime deep and wide convective cores in Foothills South triggered by lifting over lower slopes
Divergence at the Foothills North prevents convection
Nocturnal coolingDownslope flow and convergence at the foothills
leads to maxima in wide convective cores and broad stratiform regions.