Improvement of Short-term Severe Weather Forecasting Using high-resolution MODIS Satellite Data Study of MODIS Retrieved Total Precipitable Water (TPW) Data and their Impact on Severe Weather Simulations S.-H. Chen 1, A. Chen 1, J. Haase 2, Z. Zhao 1, and F. Vandenberghe 3 1 Department of Land, Air, and Water Resources, University of California, Davis, CA 2 Department of Earth and Atmospheric Sciences, Purdue University, W. Lafayette, IN 3 National Center for Atmospheric Research, Boulder, CO

o Introduction o Observations o Experiments and Preliminary Results o Summary O utline

MODIS Data  Moderate Resolution Imaging Spectroradiometer  Aboard Terra (2000) and Aqua (2002)  36 spectral bands: μm  Resolutions: 250m, 500m, 1000m  Sun-synchronous polar orbit  Mean altitude : 705 km (equator)  Width of swath : 2300 km (Terra), 2330 m (Aqua) Introduction

Retrieved MODIS Total Precipitalbe Water (TPW) Images MODIS InfraRed (IR) TPW (cm). This image shows a 50% retrieval rate. MODIS near InfraRed (nIR) TPW (cm). This image shows an 85% retrieval rate. Introduction

Observations 00Z 01/04/04 MODIS swath & Radiosonde Stations

After Correction Before Correction RMS ~ 4 mmRMS ~ 2.5 mm Observations MODIS nIR TPW vs. Radiosonde TPW

MODIS – Radiosonde vs. Latitude IR nIR

Radiosonde Stations

Hail and Strong Wind reports (June 1 and ) Severe thunderstorm activity on June 1 and 2, 2004 in Oklahoma, Texas, Arkansas and Louisiana. (Curtsey Storm Prediction Center NOAA) experiments

Model Configuration Weather Research and Forecast Model 18 UTC 1 June – 00 UTC 3 June 2004 Global Reanalysis: AVN 1 o x 1 o Domain km km Physic: Purdue microphysics New Kain-Fritsch RRTM long wave Dudhia short wave YSU PBL (Initial Time: 1800 UTC 1 June 2004) experiments

Hurricane Isidore (1800 UTC 17 – 0000 UTC 20 Sep 2002) experiments

Global Reanalysis: AVN 1 o x 1 o Domain km km km Physic: Purdue microphysics New Kain-Fritsch RRTM long wave Dudhia short wave YSU PBL Model Configuration (Initial Time: 1800 UTC 17 Sep 2002) experiments Weather Research and Forecast Model 18 UTC Sep 17 – 00 UTC Sep 20, 2002

Experiments Assimilated dataError CNTL None MOD Original MODIS nIR TPW4 mm MODC Corrected MODIS nIR TPW2.5 mm After Correction Before Correction RMS ~ 4 mmRMS ~ 2.5 mm

TPW Increment and 850 mb Wind Isidore MOD MODC

Rainfall (0 - 6h simulation) Isidore ObservationCNTL MOD MODC

Rainfall (6 - 12h simulation) Isidore ObservationCNTL MOD MODC

Rainfall (12 – 18h simulation) Isidore ObservationCNTL MOD MODC

Isidore IMOD IMODC TPW Increment and 850 mb Wind

Maximum CAPE ICNTL IMODIMODC

Results - Isidore Minimum Sea Level Pressure Maximum 10-m Wind Speed

Radar Reflectivity - Isidore Radar Image (HRD,NOAA) ICNTL IMOD IMODC (2100 UTC 19 Sep 2002)

Total Integrated Cloud (24h) ICNTL IMOD

Total Integrated Cloud (48h) ICNTL IMOD

2-km Vertical Velocity (24h) ICNTL IMOD

2-km Vertical Velocity (48h) ICNTL IMOD

S ummary o T he retrieved MODIS TPW might have biases and the RMS error is about 2-4 mm, which is comparable with that from global reanalysis over land. o T he assimilation of MODIS TPW may not be able to improve “now (i.e., at data assimilation time)” nowcasting but may have a potential to improve “future (e.g., 12h later)” nowcasting! o P reliminary results show that the assimilation of MODIS TPW has slightly positive impact on sever weather simulations (rainfall, storm intensity, etc.).