measuring high- l atitude precipitation from space
DESCRIPTION
Measuring High- L atitude Precipitation from Space. Ralf Bennartz SSEC University of Wisconsin – Madison EES – Vanderbilt University. Outline. What can we do now? Connecting to the surface Greenland mass ba lance Validation Clouds and the surface energy balance Way forward. - PowerPoint PPT PresentationTRANSCRIPT
Measuring High-Latitude Precipitation from Space
Ralf BennartzSSEC University of Wisconsin – Madison
EES – Vanderbilt University
Outline
• What can we do now?
• Connecting to the surface
• Greenland mass balance
• Validation
• Clouds and the surface energy balance
• Way forward
Contributions
• IWSSM-4 participants, in particular:
• Tristan L’Ecuyer
• Mark Kulie
• Gail Skofronick-Jackson
• Karen Boening
• Anne Walker
• Deb Vane
IWSSM-4Fourth International Workshop on Space-based Snowfall Measurement
• Held March 2013, Mammoth
• 50 participants
• Reports back to IPWG, CGMS, WMO
• Detailed recommendations from four working groups:
1. Applications & Validation
2. Radiative Properties
3. Global & Regional Detection/Estimation
4. Missions & Concepts
Ralf Bennartz, University of Wisconsin Robin Hogan, University of ReadingPaul Joe, Environment Canada Gail Skofronick Jackson, NASA GSFCGraeme Stephens, JPLDeb Vane, JPL Jeff Dozier, UCSB
Phase
C. Kidd
NEXRAD 1638Z Terra MODIS 1635Z
Type
Observing Snow with CloudSat
Active sensor Excellent sensitivity Near-global coverage Coincident measurements from other A-Train sensors
Strengths of CloudSat:
Complex relationship between reflectivity and snowfall rate/IWC Rain/snow discrimination Sampling Ground Clutter
Challenges:
T. L’Ecuyer
Global Precipitation Measurement (GPM)
• Joint NASA/JAXA mission
• 2013: As soon as NASA find a launch vehicle…
• Active: Dual-frequency Precipitation Radar (DPR) 12/17 dBZ MDS
• Passive: Multi-frequency GPM Microwave Imager (GMI): 13 channels (10-183 GHz)
Drag picture to placeholder or click icon to add
GPM - Courtesy of NASA GSFC
Global Precipitation Measurement (GPM)
• GPM-DPR
• “It is estimated that due to its higher detectability threshold, only about 7%/1% of the near-surface radar reflectivity values and about 17%/4% of the total accumulation associated with global dry snowfall would be detected by a DPR-like instrument”
(Kulie & Bennartz 2009, from global CloudSat observations)
10Earth Explorer User Consultation Meeting 19 and 20 April 2004 EarthCARE 10
EarthCARE
FOUR INSTRUMENTS:DOPPLER CLOUD RADARHIGH SPECTRAL RESOLUTION LIDARMULTI SPECTRAL IMAGERBROAD BAND RADIOMETER
A. Illingworth
Greenland Ice Sheet: Surface Mass Balance
M. van den Broeke et al. 2009
CloudSat data density
• Even nadir-only sensors (CloudSat) provide decent coverage at higher latitudes
• About 7000 obs per year per 1x2 deg box at 70 N.
CloudSat: 2006 – 2010 Mean
Greenland Ice Sheet: Surface Mass Balance
• Cloudsat derived annual mean precipitation accumulation GIS 6/2006:
• 650 Gt/yr
GPCC: 2006 – 2010
GPCC: 2006 – 2010
Snowflakes
Summit Observatory – Greenland Shupe et al. (2012)
Vermont – Bentley (ca. 1902)
Modeling Non-spherical Particles
• In the last 5 years significant progress has been made in modeling non-spherical ice optical properties
• What did we learn?
• How can we constrain them?
Uncertainty due to habit
Hiley, Kulie, Bennartz (JAMC, 2011)
Comparison to Canadian Surface Observations
Jet Propulsion LaboratoryCalifornia Institute of Technology
Workshop on Space-based Snowfall Measurement (4th IWSSM), May 6-8, 2013Boening et al.: SNOWFALL-DRIVEN MASS CHANGE ON THE EAST ANTARCTIC ICE SHEET
Ice Mass Increase and Antarctic Precipitation
CloudSat
• CloudSat observes snowfall
• Accumulated snow from CloudSat agrees well with GRACE’s observed mass
• Sublimation plays minor role
This slide from Boening et al.
Clouds and surface melting
ICECAPS observations and models show that clouds were “just right” for enhanced ice
surface melt in July 2012.
Thin liquid water clouds trap infrared radiation while still permitting enough solar radiation to
lead to maximum surface heating.
• Polar precipitation is a major gap with current satellite missions. Given the changes that are being observed in the Arctic due to climate change, a future satellite mission must focus on the capability to address polar precipitation and clouds synergistically in order to address climate and water cycle science/prediction priorities.
• There is much to gained by the precipitation and snow on the ground communities working together to outline priorities for future missions and address retrieval issues.
• If we want to observe climate signals, we need to have long-term records. Need for stable, well-calibrated long-term satellite datasets.
Conclusions