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

Typical Rain Gauge Distribution

Summer CMORPH Hydroestimator NCEP Model (GFS)

Winter CMORPH Hydroestimator NCEP Model (GFS)

Statistics are performed on a continental scale - useful - manageable - but …

JJAS Standard Deviation 3 6 9 12 15 18 21 24 3 6 9 12 15 18 21 24 Note the relative smoothness in Persiann pattern

Standard Deviation JJAS 3 6 9 12 15 18 21 24

CORRELATION JJAS .2 .3 .4 .5 .6 .7 .8 .9

CORRELATION JJAS .2 .3 .4 .5 .6 .7 .8 .9

CORRELATION DJFM .2 .3 .4 .5 .6 .7 .8 .9

CORRELATION DJFM .2 .3 .4 .5 .6 .7 .8 .9

BIAS JJAS -5 -4 -3 -2 -1 1 2 3 4 5 6

BIAS JJAS -5 -4 -3 -2 -1 1 2 3 4 5 6

Precipitation Frequency Ratio: (est./gauge) JJAS (2004-2006) .1 .25 .75 2 4 10

Ratio of # of precip. events > 25 mm/dy for JJAS (2004-2006) .1 .25 .75 2 4 10

Probability of Detection JJAS .2 .3 .4 .5 .6 .7 .8 .9

Probability of Detection JJAS .2 .3 .4 .5 .6 .7 .8 .9

Probability of Detection DJFM .2 .3 .4 .5 .6 .7 .8 .9

Probability of Detection DJFM .2 .3 .4 .5 .6 .7 .8 .9

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

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

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

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

Extra Slides

Standard Deviation DJFM 3 6 9 12 15 18 21 24

Standard Deviation DJFM 3 6 9 12 15 18 21 24

RMSE JJAS 4 8 12 16 20 24 28 32

RMSE JJAS 4 8 12 16 20 24 28 32

RMSE DJFM 4 8 12 16 20 24 28 32

RMSE DJFM 4 8 12 16 20 24 28 32

BIAS DJFM -5 -4 -3 -2 -1 1 2 3 4 5 6

BIAS DJFM -5 -4 -3 -2 -1 1 2 3 4 5 6

False Alarm Ratio JJAS .1 .2 .3 .4 .5 .6 .7 .8 .9 Note ‘color reversal’ i.e. reds are low not high values, but LOW is GOOD for FAR

False Alarm Ratio JJAS .1 .2 .3 .4 .5 .6 .7 .8 .9

False Alarm Ratio DJFM .1 .2 .3 .4 .5 .6 .7 .8 .9

False Alarm Ratio DJFM .1 .2 .3 .4 .5 .6 .7 .8 .9