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Validation of High-Resolution Precipitation Products over the U.S.
John Janowiak Climate Prediction Center/NCEP/NWS Workshop on the Evaluation of High Resolution Precipitation Products World Meteorological Organization Geneva, Switzerland December 3-5, 2007
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Typical Rain Gauge Distribution
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Summer CMORPH Hydroestimator NCEP Model (GFS)
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Winter CMORPH Hydroestimator NCEP Model (GFS)
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Statistics are performed on a continental scale
- useful - manageable - but …
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JJAS Standard Deviation 3 6 9 12 15 18 21 24
Note the relative smoothness in Persiann pattern
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Standard Deviation JJAS
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CORRELATION JJAS
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CORRELATION JJAS
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CORRELATION DJFM
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CORRELATION DJFM
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BIAS JJAS
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BIAS JJAS
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Precipitation Frequency Ratio: (est./gauge) JJAS (2004-2006)
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Ratio of # of precip. events > 25 mm/dy for JJAS (2004-2006)
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Probability of Detection
JJAS
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Probability of Detection
JJAS
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Probability of Detection
DJFM
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Probability of Detection
DJFM
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Differences due to Sampling
CMORPH(3h) - CMORPH 3B42RT - CMORPH Differences between CMORPH & 3B42RT are due to more than sampling, i.e. the manner in which the daily sums are computed Note better performance of 3B42RT in 1st 2 weeks of June “CMORPH(3h)” means daily totals made from 3hr instantaneous estimates, i.e. not the sum of the six 30 minute periods
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Findings Relevant to Workshop Goals
Recommendations to IPWG & IGWCO If they find the PERHPP results are useful then those entities should raise awareness to other relevant projects/initiatives
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Findings Relevant to Workshop Goals
How can PEHRPP link to other precip. activities? PEHRPP has a natural link to int’l programs such as GPCP and the validation effort for GPM Recommendation: effort should be made to keep GPM & abreast of PEHRPP activities and results
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Findings Relevant to Workshop Goals
Continuation & Direction of PEHRPP Considerable time & effort expended already & infrastructure exists – Recommend continuing Data & statistics generation/collection impressive but analysis to date is ad hoc Recommend a direction that focuses on analysis of results, specifically to investigate occurrences of disagreement among satellite/NWP estimates in time and space
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Extra Slides
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Standard Deviation DJFM
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Standard Deviation DJFM
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RMSE JJAS
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RMSE JJAS
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RMSE DJFM
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RMSE DJFM
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BIAS DJFM
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BIAS DJFM
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False Alarm Ratio JJAS Note ‘color reversal’ i.e. reds are low not high values, but LOW is GOOD for FAR
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False Alarm Ratio JJAS
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False Alarm Ratio DJFM
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False Alarm Ratio DJFM
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