Kinematic, Microphysical, and Precipitation Characteristics of MCSs in TRMM-LBA Robert Cifelli, Walter Petersen, Lawrence Carey, and Steven A. Rutledge Department of Atmospheric Science Colorado State University

1
Kinematic, Microphysical, and Precipitation
Characteristics of MCSs in TRMM-LBARobert
Cifelli, Walter Petersen, Lawrence Carey, and
Steven A. RutledgeDepartment of Atmospheric
ScienceColorado State University
Overview This study uses dual-Doppler and
S-band polarimetric radar data to examine
differences in the vertical structure of
convection that were observed during TRMM-LBA.
Two MCSs, occurring in distinct meteorological
regimes (see Fig. 3 in Petersen et al. poster) ,
were chosen for analysis. The first MCS occurred
on 26 January 1999 in low-level easterly flow as
a squall line with an intense leading line of
convection and a trailing region of decaying
convection and stratiform precipitation. In
contrast, the second MCS event, 25 February 1999,
occurred in low-level westerly flow. This system
exhibited little apparent organization and was
best characterized as widespread stratiform
precipitation with embedded convection. This
poster presents results showing significant
differences between these MCSs in terms of
kinematic and microphysical characteristics.
Individual CAPPIs and Cross Sections

• Method
• 2.5 (3.0) hours of continuous dual-Doppler and
  polarimetric radar data analyzed for the
  easterly (westerly) MCS at 10 minute resolution.
• Radar data partitioned into convective and
  non-convective components using reflectivity
  texture algorithm similar to Rickenbach and
  Rutledge (1998).
• Water contents and mean drop diameters calculated
  following methods of Carey and Rutledge (2000).
• Rainfall calculated over a 40,000 km2 grid using
  optimization procedure among S-Pol ZH, ZDR, and
  KDP, similar to Chandrasekar et al. (1993) and
  Petersen et al. (1999). See Carey et al. handout
  for details.

Composite Analysis

• Summary
• The two MCSs in this study, representing distinct
  meteorological regimes, have significant
  differences in terms of vertical structure
  characteristics.
• The easterly event was more intense in terms of
  overall reflectivity and kinematic structure
  (Figs. 6 and 7).
• The MCSs were sampled in similar lifecycle stages
  based on low-level reflectivity characteristics
  (Fig. 5) but displayed pronounced differences in
  terms of kinematic evolution (Fig. 10).
• Polarimetric data indicated large differences in
  the vertical distribution of hydrometeors. The
  easterly MCS showed evidence of a robust mixed
  phase region and large amounts of ice above 6 km
  that was largely absent in the westerly case
  (Figs. 3, 4, and 8).
• These observations can be used for validation of
  TRMM alogorithms and numerical models which
  utilize information on hydrometeor vertical
  structure to estimate latent heating (Tao et al.
  1993 Olson et al. 1999).

Acknowledgements This work is supported by the
NASA TRMM Program