1. The Global Precipitation Climatology Centre (GPCC) Serving the Hydro-Climatology Community
Bruno Rudolf, Andreas Becker, Udo Schneider,
Anja Meyer-Christoffer, Markus Ziese, Peter Finger
Deutscher Wetterdienst
Department of Hydrometeorology
Global Precipitation Climatology Centre

2. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

3. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

4. The Global Precipitation Climatology Centre (GPCC)
Established by the World Meteorological Organization WMO
in the year 1988
undertaken by Deutscher Wetterdienst DWD
contributes to the Global Climate Observing System GCOS
and the World Climate Research Programme WCRP
thousands of users world-wide
scientific task: quantitative assessment of global precipitation and investigation of the global water cycle
Global Precipitation Climatology Centre

5. The functions of the GPCC
 collection of observed precipitation data world-wide
 data processing, quality control, storage
 data analysis, production of gridded data fields
 distribution of the gridded data fields
 contribution to international programs
Global Precipitation Climatology Centre

6. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

7. GPCC data sources Near real-time regularly exchanged data
via the WMO Global Main Telecommunication Network
hourly/daily weather reports (SYNOP)
 ca. 6,500 stations
monthly climatological totals (CLIMAT)
 ca. 2,300 stations
ca. 8,000 stations
Non real-time:
Additional data received from ca. 190 countries
Historical data collections (CRU, FAO, GHCN)
International project data (GEWEX and other)
plus:
totally more than 64,000 stations
Global Precipitation Climatology Centre

8. GPCC data base Data coverage by country 8
Global Precipitation Climatology Centre 8

9. GPCC
data base
More than 64,000 stations providing climatic means – status 2010/10
More than 64,000 stations providing normal means – status 2010
Data used as climatologic background for GPCC gridded data sets
Global Precipitation Climatology Centre

10. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

11. GPCC
quality control
Separate storage of the data from different sources
The source specific storage of the data serves an important basis for quality control as well as
for understanding, traceability and later re-production
Global Precipitation Climatology Centre

12. GPCC quality control Quality-control with 4 levels:
Global Precipitation Climatology Centre

13. GPCC gridding Gridding of the station data for individual months
Long term mean monthly precipitation ‘normals’
Monthly precipitation anomaly gridded from station anomalies
September 2010
Gridded monthly precipitation totals
Global Precipitation Climatology Centre

14. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

15. GPCC near real-time products
Routinely produced gridded data sets
available within: application: number of stations:
5 days First Guess Anomalies drought monitoring FAO ~ 6,500
2 months Monitoring Product WCRP/GEWEX early reference ~ 7,500
Additional information provided for monitoring product
Number of stations per grid box
Sampling error
Stochastic error
Systematic error assessment
This information is updated every month
Global Precipitation Climatology Centre

16. Schedule for the release of new products
GPCC
products
Schedule for the release of new products
 Global Precipitation Mean Climatology
- period
- based on about 64,000 stations Nov 2010
 Full Data Reanalysis Version 5
- period
- based on all available data (64,000 stations) Nov 2010
 Trend analysis for selected data time-series
- period
- based on complete data time-series (~ 16,000 stations) early 2011
 publication of the methods used and results
to be submitted early 2011
Global Precipitation Climatology Centre

17. GPCC
data base
Temporal data coverage Full Data Product Version 4 and Version 5
Global Precipitation Climatology Centre

18. GPCC GPCC Product examples: GPCC Product examples:
a) First Guess Analysis for August 2010 (total & anomaly)
Global total patterns typical for La Nina season
Anomalies across Indian sub-continent contain precipitation causing Pakistan flooding
GPCC Product examples:
a) First Guess Analysis for July 2010 (total
Global Precipitation Climatology Centre

19. GPCC GPCC Product examples:
b) Monitoring (top row) and (c) Full Data Product El Nino Winter 1997/98
Please note the excellent overall quality of the monitoring product available 2 months after the fact, but also the improvement in the Full Data Product across central Africa!
Global Precipitation Climatology Centre

20. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

21. GPCC sampling error Monthly precipitation Statistical error < 10%
16 stations per grid required
Daily precipitation
Statistical error < 20%
40 stations per grid required !!
Figure: GPCC after
Jenne and Joseph,
WMO-No. 115, 1985
Global Precipitation Climatology Centre

22. GPCC Climatology 1951-2000: Number of stations per 1º grid cell
station density
Monthly
precipitation
error < 10%
16 stations
per grid,
i.e. approximately
stations
required globally
GPCC Climatology : Number of stations per 1º grid cell
Areas in dark green and blue = Sufficient station density
Global Precipitation Climatology Centre

23. GPCC, Monitoring Product, Sep 2009: No. of stations per 2,5º grid cell
station density
Daily precipitation
error < 20%
40 stations per grid required !!
i.e. approximately
stations
required globally!!
GPCC, Monitoring Product, Sep 2009: No. of stations per 2,5º grid cell
Areas in blue = Sufficient station density
Global Precipitation Climatology Centre

24. Daily data analysis
- 0.40
- 0.31
- 0.04
- 0.55
- 0.78
- 0.17
- 0.24
- 0.18
Linear trend (slope) for number of days with daily precipitation of
30 mm/d or more
period
area size
ca. 50x50 km2
msl
decrease
Global Precipitation Climatology Centre

25. Daily data analysis
+ 0.36
+ 0.30
+ 0.26
+ 0.92
+ 0.55
+ 1.05
+ 1.37
+ 0.52
+ 0.33
+ 1.55
+ 2.03
+ 1.62
+ 0.46
+ 0.15
+ 0.29
+ 0.80
+ 0.45
+ 0.95
+ 0.86
+ 0.65
+ 0.34
+ 0.07
+ 0.17
Linear trend (slope) for number of days with daily precipitation of
30 mm/d or more
period
increase
area size
ca. 50x50 km2
msl
Global Precipitation Climatology Centre

26. Daily data analysis
- 0.40
+ 0.36
- 0.31
- 0.04
+ 0.30
+ 0.26
+ 0.92
+ 0.55
+ 1.05
+ 1.37
+ 0.52
+ 0.33
- 0.55
- 0.78
- 0.17
- 0.24
- 0.18
+ 1.55
+ 2.03
+ 1.62
+ 0.46
+ 0.15
+ 0.29
+ 0.80
+ 0.45
+ 0.95
+ 0.86
+ 0.65
+ 0.34
+ 0.07
+ 0.17
Linear trend (slope) for number of days with daily precipitation of
30 mm/d or more
period
all 37 stations
increase
area size
ca. 50x50 km2
msl
decrease
Global Precipitation Climatology Centre

27. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

28. S U M E R W I N T
Number of days with heavy rain (i.e. days with totals exceeding 60 mm) for decades
Global Precipitation Climatology Centre

29. Number of dry days (i.e. days with totals less than 1 mm) for decades S U M E R W I N T
Number of dry days (i.e. days with totals less than 1 mm) for decades
Global Precipitation Climatology Centre

30. GPCC
Outline
Background and functions of the Global Precipitation Climatology Centre (GPCC)
GPCC data base and provenance
Methods in use for QC and gridding
GPCC Products
Sampling error vs. high-resolution products and trend analysis
Frequencies of extreme events
Outlook
Global Precipitation Climatology Centre

31. GPCC
Further Outlook:
GPCC Climatology 2010 and Full Data Product Version 5 (almost done)
Peer-reviewed publication on GPCC data base (ASAP)
Upload to IPCC portal – Contribution to IPCC (Q1 2011)
Selection of homogeneous time series for assembling a new homogenized precipitation re-analysis (HOMPRA) (Year 2011)
Commence near real-time daily SYNOP-based Products (Year 2011)
Extend daily analysis to re-analysis of historical data (from 2011 ongoing)
Global Precipitation Climatology Centre

32. GPCC Web site Access to GPCC‘s Precipitation Products
Global Precipitation Climatology Centre

33. GPCC GPCC staff members: Dr. Andreas Becker (scientist, head of GPCC)
Udo Schneider (scientist)
Anja Meyer-Christoffer (scientist)
Markus Ziese (scientist, new member)
Peter Finger (programmer)
Peter Stender (technician)
Astrid Heller (technician)
Jan Niclas Breidenbach (technician)
Dr. Bruno Rudolf (supervisor, dir. dept. hydrometeorology)
The Global Precipitation Climatology Centre (GPCC) is operated by the Deutscher Wetterdienst (DWD) since 1989 following the invitation of the World Meteorological Organisation (WMO).
GPCC is integrated in the Global Climate Observing System (GCOS) and in the World Climate Research Programme (WCRP).
The task of the GPCC is:
to analyse monthly global land-surface precipitation
in its spatio-temporal distribution
based on in situ observed data.
The difference of GPCC to other global climate data archive and analysis centers is:
Specialisation on precipitation
Mandate of WMO, WCRP and GCOS
Use of near-realtime synoptic and climatologic data
Integration of all major global precipitation databases and of data contributions from most countries of the world
=> the largest monthly in situ precipitation database of the world comprising more than 70,000 stations
Quality control and error assessment of observation
data from different sources and related metadata
Application specific analysis products …
Global Precipitation Climatology Centre

34. GPCC Additional Material:
The Global Precipitation Climatology Centre (GPCC) is operated by the Deutscher Wetterdienst (DWD) since 1989 following the invitation of the World Meteorological Organisation (WMO).
GPCC is integrated in the Global Climate Observing System (GCOS) and in the World Climate Research Programme (WCRP).
The task of the GPCC is:
to analyse monthly global land-surface precipitation
in its spatio-temporal distribution
based on in situ observed data.
The difference of GPCC to other global climate data archive and analysis centers is:
Specialisation on precipitation
Mandate of WMO, WCRP and GCOS
Use of near-realtime synoptic and climatologic data
Integration of all major global precipitation databases and of data contributions from most countries of the world
=> the largest monthly in situ precipitation database of the world comprising more than 70,000 stations
Quality control and error assessment of observation
data from different sources and related metadata
Application specific analysis products
Global Precipitation Climatology Centre

35. The data base Jan 1901 – Oct 2010 for gridded products
GPCC
data bas
The data base Jan 1901 – Oct for gridded products
Global Precipitation Climatology Centre

36. GPCC
data sources
Temporal data coverage of the eight different data sources and the total
GTS =
near realtime
SYNOP, CLIMAT
Global Precipitation Climatology Centre

37. GPCC gridding Gridding of the stations monthly long-term mean data
1. Interpolation of station based monthly normals to gridpoint normals
(distance of the grid-points 0.25° lat/lon)
2. Calculation of area-mean precipitation for regular grid-boxes
for all continents and islands
(grid size 0.5° lat by 0.5° lon, 1.0° lat by 1.0° lon, and 2.5° lat by 2.5° lon
Gridding of the gauge data for individual months (e.g. July 2010)
1. Calculation of precipitation (mm/month) anomalies on the stations using
all available data
2. Interpolation of station based monthly anomalies to grid-point anomalies
and calculation of area means on the grid-boxes (as above)
3. Calculation of area-mean precipitation totals for the grid-boxes by
combination of the gridded anomalies and normals
The anomaly-based interpolation is used at the GPCC since 2008
Global Precipitation Climatology Centre

38. Questionable Meta Data
GPCC
quality control
Loading new data – check station meta data against the existing data
 Station with new data
stations in the data base
decision support
Questionable Meta Data
 Expert Decision
options
Global Precipitation Climatology Centre

39. GPCC quality control Major challenges: Incorrect station location;
Separation of missing
values from 0 mm;
Separation of true from
false extremes;
 Metadata and precipitation
observation data are intensively
quality controlled and – if
necessary – corrected by GPCC
based on automatic as well as
manual QC procedures
Global Precipitation Climatology Centre

40. GPCC
quality control
Data errors discovered by comparisons and homogeneity tests
Puna/BOL: FAO and GHCN data 1930-
1948 do not belong there!!
Save/BEN: Reg. data for and
too large by a factor of 2.54!!
Barisal, Maijde Court, Comilla/BGD: GHCN data
for too small by a factor*10!!
Puerto Puyuhuapi, Coyhaique/CHL: Nat. data all „0“!!
Cantillan/PHL: Nat. data all „0“!!
Global Precipitation Climatology Centre

41. Free access to GPCC gridded data sets via internet
The Global Precipitation Climatology Centre (GPCC) is operated by the Deutscher Wetterdienst (DWD) since 1989 following the invitation of the World Meteorological Organisation (WMO).
GPCC is integrated in the Global Climate Observing System (GCOS) and in the World Climate Research Programme (WCRP).
The task of the GPCC is:
to analyse monthly global land-surface precipitation
in its spatio-temporal distribution
based on in situ observed data.
The difference of GPCC to other global climate data archive and analysis centers is:
Specialisation on precipitation
Mandate of WMO, WCRP and GCOS
Use of near-realtime synoptic and climatologic data
Integration of all major global precipitation databases and of data contributions from most countries of the world
=> the largest monthly in situ precipitation database of the world comprising more than 70,000 stations
Quality control and error assessment of observation
data from different sources and related metadata
Application specific analysis products
Number of contacts
Global Precipitation Climatology Centre