Assessment of Global Precipitation Data for IPCC Arnold Gruber and Vincenzo Levizzani

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Assessment of Global Precipitation Data for
IPCCArnold Gruber and Vincenzo Levizzani

• GOAL To provide an assessment of global
  precipitation data sets suitable for use by IPCC
• Assessment will include
• Information on input data- satellite, in situ
• Uncertainties in rainfall estimates
• Techniques for merging various sources of data
  and uncertainty in final product
• Information of spatial and temporal variability
  of precipitation including trends

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• Workshop held 3-4 Aug 2004, 15 scientist
  attended
• Assess the GPCP data set with supporting data as
  needed ( Monthly mean, 2,5 x 2.5, 1979-2003 )
• Supporting data GPCP Pentad, CMAP, SSM/I,
  Gauges, TRMM
• Other data sets for assessment should be at least
  10 years or longer and have been published.
• Assessment should be based on published or soon
  to be published literature
• Outline developed
• 23 scientists have agreed to participate

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GPCP Assessment Draft Outline

• Executive Summary (Arnold Gruber,Vincenzo
  Levizzani,)
• Introduction (motivation, brief history A.
  Gruber and V. Levizzani)
• 2. Global Precipitation Data Sets 10-12
  pp.(Chris Kidd and Kenji Nakamura)
• 2.1 Introduction (bare basics of how/why in situ
  and remote sensing estimates ) 1-2 pp.
• 2.2 GPCP Monthly mean 3-5 pp.
• 2.2.1 Input data and characteristics
• 2.2.1.1 Gauges
• 2.2.1.2 satellite estimates - SSM/I, GPI,
  OI, TOVS
• 2.2.2 Analysis procedures
• 2.2.3 Error characteristics
• 2.3 Other precipitation data sets (similar to
  2.2, but compressed ) 3-5 pp.
• 2.3.1 CMAP (Xie)
• 2.3.2 Satellite based estimates microwave,
  infrared, combined , etc (compare/contrast
  various algorithms)
• 2.3.3 TRMM PR and TMI
• 2.3.4 Gauge (GPCC, GHCN-CAMS, CRU, )
• 2.4 Chapter summary 1 page

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GPCP Assessment Outline, Contd

• 3. Spatial and Temporal Variability of
  Precipitation (comparison, validity ) 20
  pp.figs (Chet Ropelewski and Phil Arkin)
• 3.1 Introduction
• 3.2 Mean distribution (single number, single
  map, zonal profile )
• 3.3 Annual cycle (perhaps sub-monthly comes in
  here? )
• 3.4 Seasonal to inter-annual variations
• 3.5 Inter-decadal variations / trends
• 3.6 Summary
• 4. Future Directions (Emmanouil Anagnostou and
  Alberto Mugnai)
• 4.1 New-generation satellites, short-interval
  precipitation data sets,
• radar observing systems,
• Conclusions and Recommendations ( A. Gruber, V.
  Levizzani)
• Appendix 1 Authors, Contributors, and Reviewers

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GPCP Assessment contd
PROPOSED SCHEDULE Invite participation 13 August
2004 Set participants 1 September
2004 Presentation at WGDMA/GRP meeting - 18
October 2004 IPWG presentation on participants
and outline 25 October 2004 Draft documents ready
for review (6 weeks before draft) - Late
December 2004 First Draft - Late January
2005 Follow-up workshop - March/April 2005 Final
Draft review -June 2005 Final Draft -
August/September 2005