Jasmine Cetrone and Robert Houze University of Washington

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Jasmine Cetrone and Robert Houze University of Washington Powered By Docstoc
					                    Cirrus Production by Tropical Mesoscale Convective Systems
                                                                                     Jasmine Cetrone and Robert Houze
                                                                                         University of Washington
                        Motivation                                                                               Precipitation Climatologies                                                                                                                           Summary
                                                                                                                        TRMM PR MCS Convective CFADs                                                               • Anvil height and density in MCSs influenced by
Atmospheric heating by high clouds is important for                                                  16             West Africa                   Maritime Continent                     Bay of Bengal               convective intensity and amount
                                                                                                     14
tropical circulation. Many of the high clouds in the




                                                                                     Height (km)
                                                                                                     12
tropics are intimately tied to the mesoscale convective                                              10                                                                                                            • Anvil longevity possibly related to the amount of
systems (MCSs) producing most tropical precipitation.
                                                                                                      8
                                                                                                      6
                                                                                                                                                                                                                     stratiform precipitation (need case studies)
                                                                                                      4


  Summertime Cirrus Coverage
                                                                                                      2
                                                                                                                                                                                                                                                      West Africa MCSs
                                                                                                      0
                                                                                                          0   10   20 30 40 50
                                                                                                                   Reflectivity (dBZ)
                                                                                                                                        60   0   10   20 30 40 50
                                                                                                                                                      Reflectivity (dBZ)
                                                                                                                                                                           60   0   10   20 30 40 50
                                                                                                                                                                                         Reflectivity (dBZ)
                                                                                                                                                                                                              60
                                                                                                                                                                                                                                        Deep, intense convection, small stratiform area
                                                                                     • Convective precipitation in W Africa MCSs is taller and                                                                                                  Anvils shallower, but high IWP
                                                      Wylie et al. (1994)              more intense                                                                                                                                                Maritime Continent MCSs
  Summertime Precipitation                                                           • Convective precipitation in Maritime and Bengal MCSs                                                                                              Moderate convection, large stratiform areas
                                                                                       is similar, with Maritime being slightly taller                                                                                                                    Deep anvils
                                         Schumacher and Houze (2003)
                                                                                                   TRMM PR MCS Stratiform CFADs                                                                                                                      Bay of Bengal MCSs
                                                                                                     16             West Africa                   Maritime Continent                     Bay of Bengal
                                                                                                     14                                                                                                                                 Moderate convection, moderate stratiform areas
The goals of this study are to:


                                                                                     Height (km)
                                                                                                     12
                                                                                                                                                                                                                                                          Deep anvils
                                                                                                     10
                                                                                                      8
• Establish the characteristics of precipitation and anvil                                            6
                                                                                                                                                                                                                   • Consistency of time-continuous ARM site radar data
                                                                                                      4
  regions of tropical MCSs                                                                            2                                                                                                              with CloudSat implies that ARM data will provide
• Relate ARM site ground-based observations to                                                        0
                                                                                                          0   10   20 30 40 50          60   0   10   20 30 40 50          60   0   10   20 30 40 50          60
                                                                                                                                                                                                                     physical and dynamical insight into CloudSat-based
  satellite observations of MCS anvils                                                                             Reflectivity (dBZ)                 Reflectivity (dBZ)                 Reflectivity (dBZ)          climatologies
• Expand the conceptual model of cloud and                                           • Stratiform precipitation in W Africa MCSs taller and
  precipitation structure of MCSs                                                      high reflectivities aloft, indicating large ice aloft
                                                                                     • Stratiform precipitation in Maritime MCSs slightly taller
                                                                                       and with higher reflectivities aloft than Bengal                                                                                                                    Anvil Climatologies
                                                                                               TRMM PR MCS Convective Rain Fraction                                                                                                                            CloudSat MCS Anvil CFADs
               Regions of Interest                                                                   16
                                                                                                     14             West Africa                   Maritime Continent                     Bay of Bengal
                                                                                                                                                                                                                                   20
                                                                                                                                                                                                                                   18                West Africa             Maritime Continent           Bay of Bengal
                                                                                     Frequency (%)




                                                                                                                                                                                                                                   16
                                                                                                     12




                                                                                                                                                                                                                   Height (km)
MCS characteristics vary from one tropical location to                                               10
                                                                                                                                                                                                                                   14
                                                                                                                                                                                                                                   12
another. We focus on three different tropical locations,                                              8                                                                                                                            10
                                                                                                      6                                                                                                                             8
chosen because of their monsoon environments and                                                      4                                                                                                                             6
                                                                                                                                                                                                                                    4
because of the availability of time-continuous ground-                                                2
                                                                                                                                                                                                                                    2
                                                                                                      0                                                                                                                             0
or ship-based cloud radar observations.                                                                   0     20    40     60    80 100 0
                                                                                                              Convective Rain Fraction (%)
                                                                                                                                              20    40     60    80 100 0
                                                                                                                                            Convective Rain Fraction (%)
                                                                                                                                                                            20    40     60    80 100
                                                                                                                                                                          Convective Rain Fraction (%)
                                                                                                                                                                                                                                            -30 -20 -10     0 10 20 30 -30 -20 -10     0 10 20 30 -30 -20 -10     0 10 20 30
                                                                                                                                                                                                                                                   Reflectivity (dBZ)         Reflectivity (dBZ)         Reflectivity (dBZ)

                                                                                     • West Africa has very high convective rain fractions in                                                                      • W Africa anvil clouds have lower tops (even though
Summertime Stratiform Rain Fraction                                         %
                   West Africa                        Bay of Bengal
                                                                                60     MCSs, indicating stratiform regions that are smaller                                                                          convection is deeper!!)
                                                                                       and/or shorter in duration                                                                                                  • Maritime anvil clouds reach the highest
                                                                                40   • Maritime Continent has lowest convective rain fraction,
                                      Maritime Continent                               influence of monsoonal systems with large, long                                                                                                                  CloudSat MCS Thick Anvil CFADs
                                        Schumacher and Houze (2003)             20     lasting stratiform regions                                                                                                                  20
                                                                                                                                                                                                                                                     West Africa             Maritime Continent           Bay of Bengal
                                                                                                                                                                                                                                   18
                                                                                     • Bengal distribution indicates moderate convective rain                                                                                      16




                                                                                                                                                                                                                   Height (km)
                                                                                                                                                                                                                                   14
West Africa: continental monsoon climate, squall-line                                  fraction, and narrow distribution shows that MCSs in                                                                                        12

MCSs, site of the 2006 AMMA project (ground-based                                      that region are very similar to each other                                                                                                  10
                                                                                                                                                                                                                                    8
                                                                                                                                                                                                                                    6
scanning precipitation radar and ARM WACR)                                                                                                                                                                                          4
                                                                                                                                                                                                                                    2

Maritime Continent: island monsoon climate, massive                                                           ARM Ground-based Validation                                                                                           0
                                                                                                                                                                                                                                            -30 -20 -10     0    10 20 30 -30 -20 -10
                                                                                                                                                                                                                                                   Reflectivity (dBZ)
                                                                                                                                                                                                                                                                                          0 10 20 30 -30 -20 -10
                                                                                                                                                                                                                                                                                 Reflectivity (dBZ)
                                                                                                                                                                                                                                                                                                                     0 10 20 30
                                                                                                                                                                                                                                                                                                            Reflectivity (dBZ)
                                                                                                     20
MCSs, long-term data set of scanning precipitation                                                   18            Niamey WACR                        Darwin MMCR                                                  • Thick anvil defined as anvil greater than 6 km thick
                                                                                                     16
radar and ARM MMCR at Darwin, Australia                                                                                                                                                                            • Thick anvil in all regions have double minima,
                                                                                     Height (km)




                                                                                                     14
                                                                                                     12
                                                                                                     10                                                                                                              indicating high frequency of high reflectivity near
Bay of Bengal: oceanic monsoon climate, southward                                                     8
                                                                                                      6
                                                                                                                                                                                                                     cloud bottom
propagating MCSs, site of the 1999 JASMINE project                                                    4                                                                                                            • Lower maximum likely due to large aggregates?
                                                                                                      2
(ship-borne scanning precipitation radar and a                                                        0
                                                                                                          -40 -30 -20 -10 0 10 20 30 -40 -30 -20 -10 0 10 20 30
vertically pointing cloud radar)                                                                                  Reflectivity (dBZ)         Reflectivity (dBZ)                                                                                 CloudSat MCS Thick Anvil Ice Water Path
                                                                                     • Ground-based ARM WACR deployed at Niamey, Niger                                                                                             25
                                                                                                                                                                                                                                                     West Africa             Maritime Continent           Bay of Bengal
                                                                                       in West Africa during summer of 2006
                                                                                                                                                                                                                   Frequency (%)




                     Methodology                                                     • Ground-based ARM MMCR deployed at Darwin,
                                                                                                                                                                                                                                   20

                                                                                                                                                                                                                                   15
Create climatologies of TRMM Precipitation Radar (PR)                                  Australia in the Maritime Continent (long-term dataset)                                                                                     10
and CloudSat reflectivities from each of the three
                                                                                     • Statistics of reflectivity CFADS for thick anvil (>6 km)                                                                                     5
regions ONLY for MCSs during the following monsoon                                     from CloudSat and ARM vertically pointing cloud
seasons:                                                                               radars indicate that the ground-based instruments are
                                                                                                                                                                                                                                    0
                                                                                                                                                                                                                                        0        1       2
                                                                                                                                                                                                                                                               -2)
                                                                                                                                                                                                                                                                   3   4 0    1      2
                                                                                                                                                                                                                                                                                           -2)
                                                                                                                                                                                                                                                                                               3   4 0    1      2
                                                                                                                                                                                                                                                                                                                       -2)
                                                                                                                                                                                                                                                                                                                           3   4
                                                                                                                                                                                                                                                      IWP (g m                    IWP (g m                    IWP (g m
 •W. Africa: 2006 monsoon season                                                       capturing similar features
 •Maritime Continent: 2006-2007 monsoon season                                                                                                                                                                     • High IWP for W Africa thick anvils, Maritime moderate
                                                                                     • CloudSat and TRMM only provide snap-shot views of
 •Bay of Bengal: 2006 monsoon season                                                                                                                                                                                 IWP (mostly due to thicker anvil), Bengal low IWP
                                                                                       MCSs. Ground-based instruments at Niamey and
                                                                                       Darwin will allow for a time-continuous view of the                                                                         • Ice particles in intense W Africa convection likely
Hourly IR geostationary satellite data insured that the                                precipitation and anvil systems, so it is important to                                                                        larger, so particles are heavier and fall out rapidly
data collected was from MCSs.                                                          use case-studies from these regions to analyze the                                                                            producing very dense anvils (high IWP) but with lower
                                                                                       evolution of the anvil production                                                                                             tops

				
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posted:6/17/2011
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