Transcript 071115Seattle_CldPhysSem_Romatschke.ppt

Regional, Seasonal and Diurnal Variations
of Convection
in the Asian Monsoon Region
Ulrike Romatschke,
Robert Houze, Socorro Medina
Clouds and Precipitation Seminar, University of Washington, 15 November 2007
Region of Study
Outline
• Introduction
Dataset
• Regonal Variations
Comparison with Houze et al.
• Seasonal Variations
Premonsoon – Monsoon
• Diurnal Variations
Dependence on topography
• Conclusion and future Work
Dataset
• TRMM Precipitation Radar (PR), Version 6
• Products
2A23: Radar Rain Characteristics
2A25: Radar Rainfall Rate and Profile
• Monsoon Season: June - September
1999-2001
2004-2006
• Premonsoon Season: May
1999-2006
Data Processing
• Interpolation on Cartesian Grid
Gridspacing
horizontal: ~5 km
vertical: 250 m
• Search for individual systems
contiguous pixels define system
characteristic parameters (e.g. time,
location, size,…)
Height [km]
20
Definitions
• Deep Intense Convective Cores
16
12
8
4
40 dBZ echo > 10 km in hight
0
0
42.5
Distance [km]
24
• Wide Intense Convective Cores
22
Latitude
40 dBZ echo area > 1,000 km²
20
84
86
88
90
• Broad Stratiform Echos
area > 50,000 km²
Latitude
Longitude
15
20
90
95
Longitude
[dBZ]
85
Objectives
• Compare with Houze et al. (2007)
• Extend
dataset
geographical region
Premonsoon Season
• Diurnal Cycle
• Find especially active regions
Outline
• Introduction
Dataset
• Regonal Variations
Comparison with Houze et al.
• Seasonal Variations
Premonsoon – Monsoon
• Diurnal Variations
Dependence on topography
• Conclusion and future Work
Comparison
Deep Intense Convective Cores
1999-2001/2004-2006
2002-2003
Large Scale Flow Patterns during Monsoon
700 mb
1000 mb
40
30
20
10
60
70
80
90
100/60
70
80
90
100
Terrain [km]
Comparison
Wide Intense Convective Cores
1999-2001/2004-2006
2002-2003
Comparison
Broad Stratiform Systems
1999-2001/2004-2006
2002-2003
Outline
• Introduction
Dataset
• Regonal Variations
Comparison with Houze et al.
• Seasonal Variations
Premonsoon – Monsoon
• Diurnal Variations
Dependence on topography
• Conclusion and future Work
Deep Intense Convective Cores
Premonsoon
Monsoon
Surface p [mb] and v
1000 mb
500 mb v
700 mb
The Indian Dry-Line
Weston (1971)
The Indian Dry-Line
Monsoon
Premonsoon
200 mb
700 mb
1000 mb
Wide Intense Convective Cores
Premonsoon
Monsoon
Wide vs. Deep Intense Convective Cores
Premonsoon
Premonsoon
Wide vs. Deep Intense Convective Cores
Monsoon
Monsoon
Wide vs. Deep Intense Convective Cores
Ganges Delta
Monsoon
Broad Stratiform Systems
Premonsoon
Monsoon
Broad Stratiform Systems
Rain Climatology
Xie et al. (2006)
Monsoon
Outline
• Introduction
Dataset
• Regonal Variations
Comparison with Houze et al.
• Seasonal Variations
Premonsoon – Monsoon
• Diurnal Variations
Dependence on topography
• Conclusion and future Work
Diurnal Cycle, Monsoon
Diurnal Cycle
Diurnal Cycle
Diurnal Cycle, Monsoon
Diurnal Cycle
Deep Intense Convective Cores
Monsoon
Diurnal Cycle
Deep Intense Convective Cores
Monsoon
Diurnal Cycle
Deep Intense Convective Cores
Monsoon
Diurnal Cycle
Deep Intense Convective Cores
Monsoon
Diurnal Cycle
Deep Intense Convective Cores
Premonsoon
Diurnal Cycle
Deep Intense Convective Cores
Premonsoon
Surface p [mb] and v
Weston (1971)
Xie et al. (2006)
Diurnal Cycle, Deep Intense Convective Cores, Premonsoon
Zuidema (2002)
Mean percent high cloudiness
Cloud Top < 210 K
May – September 1999
Diurnal Cycle, Monsoon
Diurnal Cycle, Monsoon
Wide Intense Convective Cores
1999-2001 vs. 2004-2006
1999-2001
2004-2006
Diurnal Cycle
Wide Intense Convective Cores
Monsoon
Diurnal Cycle
Wide Intense Convective Cores
Monsoon
Xie et al. (2006)
Diurnal Cycle
Wide Intense Convective Cores
Premonsoon - Monsoon
Diurnal Cycle
Wide Intense Convective Cores
Premonsoon
Diurnal Cycle, Monsoon
Diurnal Cycle, Monsoon
Diurnal Cycle
Broad Stratiform Systems
Monsoon
Diurnal Cycle
Broad Stratiform Systems
Monsoon
Diurnal Cycle
Broad Stratiform Systems
Monsoon
Diurnal Cycle
Broad Stratiform Systems
Monsoon
Williams and Houze (1987)
Outline
• Introduction
Dataset
• Regonal Variations
Comparison with Houze et al.
• Seasonal Variations
Premonsoon – Monsoon
• Diurnal Variations
Dependence on topography
• Conclusion and future Work
Conclusions
• Larger independent dataset seems to confirm
Houze et al. (2007)
• Premonsoon – Monsoon
• Shift in places of occurrence of Deep and Wide Intense Convective
Cores.
• More Wide Intense Convective Cores and Broad Stratiform
Systems over the ocean during Monsoon.
• Diurnal Cycles
• Strong afternoon peak in Deep Intense Convective Cores.
• Afternoon and night peaks in Wide Intense Convective Cores.
• Evening minimum in Broad Stratiform Systems.
• Rain climatology compares
• with Broad Stratiform Systems over the ocean.
• with Wide Intense Convective Cores at the Himalayan Foothills.
• not with Deep Intense Convective Cores.
Conclusions
• Larger independent dataset seems to confirm
Houze et al. (2007)
This is just the beginning!
• Premonsoon – Monsoon
• Shift in places of occurrence of Deep and Wide Intense Convective
Cores.
• More Wide Intense Convective Cores and Broad Stratiform
Systems over the ocean during Monsoon.
• Diurnal Cycles
• Strong afternoon peak in Deep Intense Convective Cores.
• Afternoon and night peaks in Wide Intense Convective Cores.
• Evening minimum in Broad Stratiform Systems.
• Rain climatology compares
• with Broad Stratiform Systems over the ocean.
• with Wide Intense Convective Cores at the Himalayan Foothills.
• not with Deep Intense Convective Cores.
Future Work
• Get 2002/2003 Version 6 data.
• Statistics for other variables.
• Look at specific regions
• physical background
• different variable fields (e.g. wind)
• satellite data
Variables
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Orbitnumber
• Number of convective pixels
Date
• Number of stratiform pixels
Time
• Convective, stratiform, total
Number of pixels 3D
• rain rate
Number of pixels 2D
• volumetric rain rate
Latitude
• rain fraction
Longitude
• area fraction
Height
Longest horizontal dimension
Height of terrain
Area
Future Work
• Get 2002/2003 Version 6 data.
• Statistics for other variables.
• Look at specific regions
• physical background
• different variable fields (e.g. wind)
• satellite data
Future Work