Wednesday, July 24, 2013

It's raining, it's pouring

Sou | 1:31 AM One comment so far. Add a comment

Perennially Puzzled Bob Tisdale has written a second article on precipitation, on WUWT.  It's mainly a gripe that he cannot find data sets that agree.  When I wrote about his first gripe I made the uninformed observation that precipitation must be one of the most difficult things to monitor globally.  This would be so for any number of reasons that I expect readers here could imagine.

Anyway I've done a bit more reading and came across this paper by Udo Schneider et al (2013), titled: GPCC's new land surface precipitation climatology based on quality-controlled in situ data and its role in quantifying the global water cycle

Here is the abstract:
In 1989, the need for reliable gridded land surface precipitation data sets, in view of the large uncertainties in the assessment of the global energy and water cycle, has led to the establishment of the Global Precipitation Climatology Centre (GPCC) at Deutscher Wetterdienst on invitation of the WMO.
The GPCC has calculated a precipitation climatology for the global land areas for the target period 1951–2000 by objective analysis of climatological normals of about 67,200 rain gauge stations from its data base. GPCC's new precipitation climatology is compared to several other station-based precipitation climatologies as well as to precipitation climatologies derived from the GPCP V2.2 data set and from ECMWF's model reanalyses ERA-40 and ERA-Interim.
Finally, how GPCC's best estimate for terrestrial mean precipitation derived from the precipitation climatology of 786 mm per year (equivalent to a water transport of 117,000 km3) is fitting into the global water cycle context is discussed.

The paper is a very easy read.  It goes into a lot of detail, describing how the team collects data, corrects it, stores it etc.  And towards the end it has some information about global precipitation patterns, among other things.  I recommend it.

BTW - I'd say my uninformed observation was pretty close to the mark.

1 comment:

  1. It's raining, it's pouring, Bob Tisdale is boring. He might have noticed that all three datasets have their caveats. For example GPCP is 1x1, the others 25.5x2.5. CAMS is admitted, right on the download page, to be not good for long term analysis. GPCP does a better job of integrating differing satellite sources (as far as I can tell). It is rather hard to draw conclusions from all of that.


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