# Presentation: 164090

## Characteristics of Convective Systems Observed During TRMM-LBARob Cifelli, Steve Nesbitt, and Steven A. RutledgeColorado State University

## Motivation for TRMM-LBA

- •  Amazon one of three primary regions of ascent in the Walker Circulation and an upward branch in the Hadley Circulation
- •  Copious precipitation/latent heat release, but relatively few detailed studies of deep convection

## TRMM-LBA

- Joint with Large-scale Biosphere Atmosphere experiment (LBA)
- Conducted in the State of Rondonia, Brazil (11oS, 62 W; SW corner of Amazon)  during Jan.-Feb. 1999
- Goals:
- Validation of TRMM satellite products
- Validation of cloud models (e.g., GCEM)
- Physics of convection and the processes driving convection
- Instrumentation:
- Ground radar:  S-pol and TOGA radars (kinematics, microphysics, rainfall)
- Aircraft:  ER-2 (TRMM simulator) and UND Citation (microphysics)
- Soundings (3-Tethersonde and 4-Radiosonde)
- NASA MSFC Brazilian Lightning Detection Network
- NOAA dual-frequency wind profiler
- Four raingauge networks, 2DVD and JW disdrometers
- Other platforms (e.g., CCN, fluxes, flat plate antennas etc.)

## Radars and Tethersonde

## TRMM-LBA Aircraft

## Slide 6

## TRMM-LBA: Evidence of Convective Regimes

- • West U-wind= Low CI, moist troposphere; monsoon-like convection
- • Easterly  U-wind= High CI, more dry troposphere; break-like convection

## Brazilian Lightning Detection Network (BLDN)

-  Oscillations apparent
- • East (west) anomalies =more (less) lightning.

## Time series PDFs of TRMM precipitation feature 30 dBZ echo top heights (left) and minimum 85 GHz PCTDJFM 1998-1999

- TRMM-LBA Radar Ops

- TRMM-LBA Radar Ops

- Petersen et al. (2002)

## Radar Observed Contrasts in TRMM-LBA Convection: Water Content 

** **Paucity of ice in mid-upper troposphere

- Easterly Convection

- Westerly Convection

-  Active mixed phase microphysics
-  Copious ice in mid-upper troposphere

- Significant differences in the vertical distribution of hydrometeors

- Ice (gm m-3 - thin solid lines), liquid (gm m-3 - color contours), mean drop diameter (mm - heavy solid lines)

## Mixed Phase Zone (4 - 8 km) Precipitation Ice and Rain Mass

- ICE

- RAIN

- Frequency Distributions

- Polarimetric radar analyses to identify microphysical differences
- Courtesy:  Dr. Lawrence Carey, Texas A&M

## Slide 12

## Radar Observed Contrasts in TRMM-LBA Convection: Vertical Mass Transport 

-  Significant differences in intensity and lifecycle characteristics

- Height (km)

- Profiler observations at Ji-Parana, Brazil 15 February 1999 (East)
- Stratiform rain with embedded convective cells
- Updrafts greater than 2 m/s above 6 km altitude
- Break period convective system viewed by profiler—C. Williams and K. Gage

## Relative Frequency Histograms of S-POL Radar Parameters

- 16 JAN 99 – 28 FEB 99

## Composite Q1 Profiles

-  ER Convective Q1 is broader due to importance of ice processes
-  Difference in total Q1’s largely due to WCSF

## PDFs of TRMM precipitation feature characteristics as a function of wind regime in RondôniaDJFM 1997-2000

- Petersen et al. (2002)

- TMI
- 85 & 37
- GHz ice scattering
- PCTs

- PR echo
- top heights

- Higher optical depths of ice

- Higher radar tops

## Comparisons of PR, Ground-Based and Airborne Radar Data in TRMM LBA

- Heymsfield et al. (2000)

## Model-Observations Comparison, Tao and Lang, GSFC

- Observed CAPPI reflectivity

- Simulated CAPPI reflectivity

- Observed CFAD reflectivity

- Simulated CFAD reflectivity

- Comparisons between model and observations have led to improved microphysical parameterizations and latent heating profiles

## Lessons Learned From TRMM-LBA

- Dual polarimetric radar is key for characterizing microphysical variability within regimes
- Gauge and disdrometer network important to evaluate errors in polarimetric rainfall measurements
- TRMM-LBA ground network provided a template for GPM GV
- More work is needed to understand the impact of regimes on satellite algorithms