Skofronick-Jackson, Weinman, Wang, ChangGPM Planning Mtg Aug 2001

High Frequency Microwave Observations of Frozen

HydrometeorsGail Skofronick Jackson

University of Maryland, Baltimore County,

Goddard Earth Science and Technology Center

Goddard, Code 975, gailsjackson@ieee.org

James A. Weinman, James R. WangNASA Goddard Space Flight Center, Code 975

Dong-Eon ChangCenter for Earth Observing and Space Research

George Mason University

Fairfax, VA

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Challenges of GPM

• Measure extratropical precipitation, much of which is light rain and snow.This is especially critical to support land hydrology.

• Improve sampling of all types of precipitation, including snow.

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Motivation• What information regarding frozen

hydrometeors and snowfall in the atmosphere can be obtained from high frequency microwave measurements?

• Improve understanding of hydrometeor-radiometer-radar relationships

• Heritage: Early work by A. T. C. Chang and J. R. Wang, (1992) using the Airborne Advanced Microwave Moisture Sounder (AMMS).

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Snowfall Obs. Over LandNew England experienced a significant blizzard on 3/6/01. The

85.5 GHz PCT responds mainly to snow on the ground that extends over Canada whereas the low 183+7 AMSU-B brightness

temperatures coincide with reported snowfall at the time.

SSM/I 85 GHz AMSU-B 183±7 GHz

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Not Just A Surface Feature(Left) repeat of 183+7 GHz AMSU-B data at 2301UTC on 3/5/01 and (Right) data from the same sensor at 1302 UTC on 3/6/0.

Note that the low brightness temperatures (snowfall?) have moved eastward off shore.

14 Hours later AMSU-B 183±7 GHz

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Not Just a Surface Feature:WSI Radar Mosaic

Note reduction of snowfall over VT.

05 March 2001 2300 06 March 2001 1300

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

MM5 Precipitation Distribution vs AMSU-B

AMSU-B 183±7 GHz MM5 Precipitation

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Content and Weighting Fcns from MM5 Model of 3/6/01 Blizzard

1) Unlike the cloud-free case, these weighting functions are themselves function of the cloud distribution

2) Note order of magnitude increase in weighting function at high frequencies

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Height Slicing using Water Vapor Absorption

Note the absence of low brightness temperature concentrations over New England (left) and their presence (right).

• 183 + 1 GHz AMSU-B • 183 + 3 GHz AMSU-B

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

CAMEX-3 Observations

EDOP(ER-2 Doppler Radar)

MIR(Millimeter-wave Imaging Radiometer)89 - 340 GHz

AMPR(Advanced Microwave Precipitation Radiometer)10 – 85 GHz

Qualitative Profile

Retrievals

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Microwave Weighting Functions for a Cirrus Anvil Case

Note that unlike the cloud-free case, these weighting functions are themselves a function of the cloud distribution

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Retrieval Results for Two Anvil Profiles using Selected Channel Sets

GPM Planning Mtg Aug 2001 Skofronick-Jackson, Weinman, Wang, Chang

Conclusions/Summary

• HF microwave channels reveal ice and snow features missed at TMI frequencies.

• Snowfall appears observable from HF where water vapor absorption obscures the ground and may reveal ice profiles.