Wcrp workshop on determination of solid precipitation in cold climate regions
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WCRP Workshop on Determination of Solid Precipitation in Cold Climate Regions PowerPoint PPT Presentation

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WCRP Workshop on Determination of Solid Precipitation in Cold Climate Regions. Fairbanks, Alaska June 9-14, 2002. Organized by: WCRP CliC and GEWEX Projects Host: University of Alaska Fairbanks (UAF) Sponsors : WCRP and GCOS Meteorological Service of Canada

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WCRP Workshop on Determination of Solid Precipitation in Cold Climate Regions

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WCRP Workshop on Determination of Solid Precipitation in Cold Climate Regions

Fairbanks, Alaska

June 9-14, 2002

Organized by: WCRP CliC and GEWEX Projects

Host: University of Alaska Fairbanks (UAF)



Meteorological Service of Canada

NOAA Arctic Research Office

NOAA/NASA GEWEX Americas Prediction Project

UAF International Arctic Research Centre

UAF Water and Environmental Research Centre

  • Participation:

    • Over 50 invited participants from 13 countries.

    • Representation from the major cold regions of the world including North and South America, Scandinavia, Eurasia, China and the Arctic and Antarctic.

    • Experts on cold climate precipitation; in-situ measurement and remote sensing; development of precipitation adjustment techniques and implementation on regional and global scales; major field programs; global data archives and modeling.

    • Over 50 paper and poster presentations.

Workshop Objectives:

  • to review the current status of measuring or determining precipitation, especially solid precipitation, in cold climate regions

  • to identify gaps and issues

  • to recommend actions that will allow us to determine precipitation over a range of time and space scales for climatological and hydrological analyses, regional water budgets, validation and process experiments and models

WG1: Precipitation Measurement

  • Conventional measurement methods

  • Alternative strategies

  • New technologies

WG1: Precipitation Measurement


  • impact of automation on precipitation measurement and related QA/QC challenges;

  • continuing need for conventional point precipitation measurements against declining networks in many countries;

  • accessibility of up-to-date meta data;

  • need to blend (fuse or combine) data from different sources (in-situ, model, satellite);

  • need to maintain reasonable expectations on what satellite and radar technologies are able to provide; and

  • need for further intensive field efforts to address scaling.

WG1: Precipitation Measurement

Suggested actions:

  • establish a WCRP working group to develop guidelines on the minimum station density required for climate research studies on solid precipitation in cold climate regions;

  • conduct urgently needed research to determine how to obtain climate quality data from automated weather observing systems--need to define and attribute “climate”-quality to operational weather observing systems/sites;

  • encourage national research agencies to establish programs to provide support for the development of new instruments to measure solid precipitation in high latitude region; and

  • identify and establish intercomparison sites for standardized testing of new technology, such as radar, hot plate, pressure, or blowing snow

WG2: Measurement Errors and Adjustment Procedures


  • is there a need for intercomparison of adjustment procedures;

  • how can we quantify and/or represent the error in the adjusted measurements and monitor the improvements made by making these adjustments;

  • what are the errors in gridding and creating gridded products; what must be done to the existing and planned national networks and archives to provide consistent adjustments to facilitate comparisons among national, regional and global climatologies; and

  • what is the practicality of adjustments related to time scale, space scale and metadata requirements.

WG2: Measurement Errors and Adjustment Procedures


  • there is real value in reporting adjusted precipitation and there is a continuing need for ongoing intercomparisons;

  • correction factors are compromised by limited data sets and there are regional/climatic differences in adjustment factors;

  • the application of real time / dynamic adjustments should be done with caution—we must first determine the limitations;

  • we need to adapt to changing user needs; and

  • good meta data and station histories are not only important, but essential.

WG3: Global Precipitation Data Sets


  • what are the principal user requirements for a global precipitation data set;

  • what are the limitations in the current global precipitation data sets;

  • what improvements could/should be made in these global precipitation data sets;

  • what new measurement techniques (e.g. GPM) could provide data for these global data sets;

  • what research and development is needed to prepare for these new measurement and data systems;

  • what are the limitations in merging satellite and in-situ products and how are these limitations overcome; and

  • is there a role for a data-model mix in producing global precipitation data products?

WG3: Global Precipitation Data Sets

Research needs:

  • Improve the use of wind information to enhance adjustments of snow both at a point and over a region;

  • optimizing the blend of moisture flux convergence and gauge measurements in data sparse areas (e.g. Greenland);

  • determining how to incorporate non-standard data (e.g. ice cores) into precipitation climatologies;

  • development of models for downscaling to topography, blending strategies for data assimilation (e.g. define error characteristics), and interpolation to determine large scale precipitation patterns in the absence of data;

  • estimation of snowfall and snow pack in mountainous regions; and

  • techniques to distinguish between solid and liquid precipitation.

WG3: Global Precipitation Data Sets


  • provide enthusiastic support to GPM by developing regional baseline data streams for algorithm development;

  • develop a strategy for exploiting new technologies in the development of algorithms and models for third and fourth generation precipitation climatologies;

  • use daily precipitation as a building block for precipitation climatologies;

  • develop a system for a critical mass of snow accumulation stations in Antarctica to provide accumulations with a one-month data latency;

  • obtain comprehensive meta data on gauge placement;

  • ensure full data rescue and digitization of “at risk” cold season data sets; and

  • ensure CliC and GEWEX address the priority research needs (listed above) for developing global precipitation data sets.

Gaps and common issues:

  • precipitation measurement in mountainous regions;

  • measurement of low intensity solid precipitation events;

  • measurement /estimation of precipitation in Antarctica;

  • solid precipitation over sea ice and ice covered Arctic Ocean;

  • how to quantify the errors associated with adjustment procedures and determine the limitations on time and space scales for adjustments;

  • gridding—what analysis method to be used and sampling error depend on amount of data;

  • GPCC—some countries have not provided data since gridded products distributed free;

  • GPCC—sampling errors have to be addressed by CliC, also how to proceed and methods that can be implemented; and

  • how to improve the linkage to the GCM community and determining modeling needs.

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