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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 - PowerPoint PPT Presentation
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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
Monitoring ProductPurpose: Precipitation Monitoring(input to GPCP and CMAP)
First Guess ProductPurpose: Drought Monitoring(by FAO and other institutes)
Available spatial resolutions: 1.0° and 2.5° lat/long(GPCC-internally calculated on 0.5° lat/long)
Available: 2 months laterData 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: 3 - 5 days after end of monthData base: 5,500 stations Data source: SYNOP data only Quality control: automatic onlyAvailable products: Only the current product
Monthly Operational GPCC Products (near real-time)
Full Data ReanalysisPurpose: 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 43,000 stations 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 9,343 stations
- Period 1951 - 2000
- High level quality and homogeneity control
- Analysis based on climatic background
Updates after significant improvements of the data base (about once per year)
Available spatial resolution: 0.5°, 1.0° and 2.5° Lat/Lon
GPCC Data Reanalysis Products
Standard GPCC products provided on the grid:
monthly precipitation total
number of stations
monthly precipitation anomaly
Normals:Mean monthly precipfrom 1961 to 1990based on 30.000 stations
absolute measuring error (mm/mon) relative measuring error (%)
fraction of solid precipitation (%)fraction of liquid precipitation (%)
New GPCC products based on daily synoptic data
Will be included to the web pages Visualizer soon
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
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
Development of the GPCC database
Collection of long time-series following the request of GCOS and promoted by the AOPC
Status of January 2006
The current database of GPCC‘s products
Number of stations being selected for the different productsin the course of time (status of February 2005)
176 countries delivering data to GPCCUsual delay in data delivery approx. 1 to 5 years
The GPCC database in preparation
/ / / / / / / / / - additional data received in 2006, currently being processed (partly overlapping, partly complementing the existing data)
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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
- 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 forthe months and the year
VASClimO: A homogenised 50-Year Climatology
based on 9,343 selected stations
Seasonal precipitation trends 1951-2000 over Northern and Southern Europe
50-Year Climatology: Overall Results
Results from GPCC project VASClimO (C. Beck, J. Grieser and B. Rudolf, 2005)
spring
winterautumn
summer
Mean precipitation (all continents) for the 1951-2000 climatology complemented by the 2001-2005 near real-time Monitoring Product
Monthly area mean anomaly and 12 months running mean
Monthly area mean precipitation and 12 months running mean
The real-time data do not fit the homogenized time-series !!
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
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)
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)
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
Systematic error correction factors for Europe
Many non-synop stations are located in gardens, villages etc.and well protected from wind effects by vegetation.
(here: Climate Reference Station Asheville NC)
Meta Data Information:type of gauge usedsourrounding properties
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
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).
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).
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.
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.
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
Conclusions and Outlook
Status and Plans of the Global Precipitation Climatology Centre (GPCC)
Thank you for your attention!
More information from http://gpcc.dwd.de