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Status and Plans of the Global Precipitation Climatology Centre (GPCC)

Status and Plans of the Global Precipitation Climatology Centre (GPCC) Bruno Rudolf, Tobias Fuchs and Udo Schneider (GPCC) Overview: Introduction to the gauge-based gridded precipitation data sets Development of the observational database Climatological evaluation of the time-series

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Status and Plans of the Global Precipitation Climatology Centre (GPCC)

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  1. Status and Plans of the • Global Precipitation Climatology Centre (GPCC) • Bruno Rudolf, Tobias Fuchs and Udo Schneider (GPCC) • Overview: • Introduction to the gauge-based gridded precipitation data sets • Development of the observational database • Climatological evaluation of the time-series • Systematic measuring error with a focus on solid precipitation • Outlook

  2. Monthly Operational GPCC Products (near real-time) First Guess Product Purpose: Drought Monitoring (by FAO and other institutes) Available: 3 - 5 days after end of month Data base:5,500 stations Data source: SYNOP data only Quality control: automatic only Available products: Only the current product Monitoring Product Purpose: Precipitation Monitoring (input to GPCP and CMAP) Available: 2 months later Data base:6,500 to 7,000 stations Data sources:SYNOP data plus monthly CLIMAT and CPC Quality control: automatic and visual Available products: from Jan. 1986 onwards up to near present Available spatial resolutions: 1.0° and 2.5° lat/long (GPCC-internally calculated on 0.5° lat/long)

  3. GPCC Data Reanalysis Products Full Data Reanalysis Purpose: verification of models continental water cycle studies UNESCO, GTN-H, GRDC Use of all data being available at GPCC - Current version 3 based includes up to 43,000stations in one month - Period: 1951 - 2004 - Quality control/assurance for meta data and monthly precipitation data 50-Year Climatology Purpose: variability studies trend analysis (GCOS, IPCC) available since Apr 2005 Use of selected data time-series - Current Version 1.1 with 9,343stations - Period 1951 - 2000 - High level quality and homogeneity control - Analysis based on climatic background Available spatial resolution: 0.5°, 1.0° and 2.5° Lat/Lon Updates after significant improvements of the data base (about once per year)

  4. Standard GPCC products provided on the grid: monthly precipitation total monthly precipitation anomaly Normals: Mean monthly precip from 1961 to 1990 based on 30.000 stations number of stations

  5. New GPCC products based on daily synoptic data fraction of liquid precipitation (%) fraction of solid precipitation (%) relative measuring error (%) absolute measuring error (mm/mon) Will be included to the web pages Visualizer soon

  6. Status and Plans for the • Global Precipitation Climatology Centre (GPCC) • Bruno Rudolf, Tobias Fuchs and Udo Schneider (GPCC) • Overview: • Introduction to the gauge-based gridded precipitation data sets • Development of the observational database • Climatological evaluation of the time-series • Systematic measuring error with a focus on solid precipitation • Outlook

  7. Development of the GPCC database Status in 2001 data collected for the period from 1986 onwards as requested by GEWEX Decline of data after 1986 due to data delivery delays of the participating countries

  8. Development of the GPCC database Status of January 2006 Collection of long time-series following the request of GCOS and promoted by the AOPC

  9. The current database of GPCC‘s products Number of stations being selected for the different products in the course of time (status of February 2005) 176 countries delivering data to GPCC Usual delay in data delivery approx. 1 to 5 years

  10. The GPCC database in preparation / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / - additional data received in 2006, currently being processed (partly overlapping, partly complementing the existing data)

  11. Status and Plans for the • Global Precipitation Climatology Centre (GPCC) • Bruno Rudolf, Tobias Fuchs and Udo Schneider (GPCC) • Overview: • Introduction to the gauge-based gridded precipitation data sets • Development of the observational database • Climatological evaluation of the time-series • Systematic measuring error with a focus on solid precipitation • Outlook

  12. VASClimO: A homogenised 50-Year Climatology based on 9,343 selected stations • - monthly precipitation total • - interpolation error • - only station data with a minimum of 90% data availability • - 50 year mean precipitation • standard deviation • - absolute trend • relative trend • - trend significance • - trend/noise ratio • - variation coefficient Variables available on a 0.5° grid: 1951 to 2000 Time-series (600 months) Statistical results for the months and the year

  13. 50-Year Climatology:Overall Results Seasonal precipitation trends 1951-2000 over Northern and Southern Europe spring summer winter autumn Results from GPCC project VASClimO (C. Beck, J. Grieser and B. Rudolf, 2005)

  14. Mean precipitation (all continents) for the 1951-2000 climatology complemented by the 2001-2005 near real-time Monitoring Product Monthly area mean precipitation and 12 months running mean Monthly area mean anomaly and 12 months running mean The real-time data do not fit the homogenized time-series !!

  15. Status and Plans for the • Global Precipitation Climatology Centre (GPCC) • Bruno Rudolf, Tobias Fuchs and Udo Schneider (GPCC) • Overview: • Introduction to the gauge-based gridded precipitation data sets • Development of the observational database • Climatological evaluation of the time-series • Systematic measuring error with a focus on solid precipitation • Outlook

  16. Systematic Gauge Measuring Error The problem: Precipitation amounts measured by raingauges are systematically underestimated. For estimation of reliable global or regional precipitation amounts, an adequate correction of the data used or of the product is required. (Fig. after SEVRUK 1989)

  17. Precipitation phase and windspeed are the most important parameters for correction of raingauge observations Correction ratio in % of the data measured by the Hellmann gauge (without windshield) as a function of wind speed for solid, liquid and mixed precipiation (T. Günther, DWD, in Goodison et al. WMO 1998)

  18. Systematic error correction factors for Europe • Mean correction factors for the area of Europe: • Monthly long-term mean error estimate after Legates • Error calculated from daily SYNOP and its monthly means for 2001 • Large for snow regions and cold season

  19. Meta Data Information: type of gauge used sourrounding properties Many non-synop stations are located in gardens, villages etc. and well protected from wind effects by vegetation. (here: Climate Reference Station Asheville NC)

  20. Status and Plans for the • Global Precipitation Climatology Centre (GPCC) • Bruno Rudolf, Tobias Fuchs and Udo Schneider (GPCC) • Overview: • Introduction to the gauge-based gridded precipitation data sets • Development of the observational database • Climatological evaluation of the time-series • Systematic measuring error with a focus on solid precipitation • Outlook

  21. Conclusions and Outlook 1. Users of gridded GPCC gauge data sets should not use any product but should reflect their application purpose and select the optimized product (best spatial coverage or best homogeneity).

  22. Conclusions and Outlook 1. Users of gridded GPCC gauge data sets should not use any product but should reflect their application purpose and select the optimized product (best spatial coverage or best homogeneity). 2. The real systematic gauge measuring error is smaller than the climatological estimates published by Legates & Willmott (1989).

  23. Conclusions and Outlook 1. Users of gridded GPCC gauge data sets should not use any product but should reflect their application purpose and select the optimized product (best spatial coverage or best homogeneity). 2. The real systematic gauge measuring error is smaller than the climatological estimates published by Legates & Willmott (1989). 3. The instrument type and the local environment is unknown for most of the gauge stations. Even with the new method, the calculated gauge error is a rough bias estimate.

  24. Conclusions and Outlook 1. Users of gridded GPCC gauge data sets should not use any product but should reflect their application purpose and select the optimized product (best spatial coverage or best homogeneity). 2. The real systematic gauge measuring error is smaller than the climatological estimates published by Legates & Willmott (1989). 3. The instrument type and the local environment is unknown for most of the gauge stations. Even with the new method, the calculated gauge error is a rough bias estimate. 4. The GPCC data base is still growing. In particular, the collection of precipitation normals will increase to about 50,000 stations. The normals will be analysed on the orographic background.

  25. Conclusions and Outlook 1. Users of gridded GPCC gauge data sets should not use any product but should reflect their application purpose and select the optimized product (best spatial coverage or best homogeneity). 2. The real systematic gauge measuring error is smaller than the climatological estimates published by Legates & Willmott (1989). 3. The instrument type and the local environment is unknown for most of the gauge stations. Even with the new method, the calculated gauge error is a rough bias estimate. 4. The GPCC data base is still growing. In particular, the collection of precipitation normals will increase to about 50,000 stations. The normals will be analysed on the orographic background. 5. In future, all GPCC products will be calculated using high-resolution climatological precipitation fields as analysis background

  26. Status and Plans of the Global Precipitation Climatology Centre (GPCC) Thank you for your attention! More information from http://gpcc.dwd.de

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