H-SAF Product Validation Report (PVR) PR-OBS-3

Products Validation Report, 30 May 2010 - PVR-03 (Product PR-OBS-3) Page 50
4.6 Validation in Poland (IMWM)
The facilities available to IMWM, and the methodology adopted for validation, are described in section
3.4.5. The ground truth is provided by rain gauge networks.
Table 12 reports the results of the final validation campaign of the Development Phase for PR-OBS-3.
Table 12 - Summary results of PR-OBS-3 validation in Poland by IMWM
H03 v1.4 Poland Land Validation period: 1 st January 2009 - 31 March 2010 - Threshold rain / no rain: 0.25 mm/h
Gauge Class Jan Feb Mar Apr Mag Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar
Number of > 10 mm/h 32 7 174 212 2097 4696 3862 2522 894 635 64 40 6 14 103
comparisons 1-10 mm/h 8192 14191 45506 3455 50847 71199 40136 36318 14021 62455 40968 23617 13435 11567 17468
(ground obs.) < 1 mm/h 31783 62299 85087 3722 52051 82127 40132 31722 18355 93534 60128 47125 47740 38561 38425
> 10 mm/h -82.7 -16.6 -17.6 -16.8 -20.7 -19.4 -22.6 -18.2 -17.8 -33.8 -25.4 -22.0 -12.2 -14.4 -13.8
ME (mm/h) 1-10 mm/h -0.79 -1.51 -1.70 -1.96 -1.48 -1.76 -1.98 -2.11 -2.26 -1.33 -1.52 -1.63 -1.56 -1.50 -1.85
< 1 mm/h -0.35 -0.56 -0.56 -0.19 -0.14 -0.17 -0.14 -0.19 -0.30 -0.29 -0.45 -0.55 -0.56 -0.53 -0.56
> 10 mm/h 167 6.15 28.6 9.74 68.1 13.9 55.1 11.9 13.4 130 39.5 15.7 2.04 3.55 3.03
SD (mm/h) 1-10 mm/h 1.43 0.71 0.99 2.11 2.45 2.28 2.26 2.07 2.26 3.11 0.96 0.86 0.85 0.82 1.21
< 1 mm/h 0.83 0.17 0.19 0.94 1.27 1.14 1.09 0.80 1.70 2.20 0.44 0.20 0.19 0.21 0.17
> 10 mm/h 186 17.7 33.6 19.4 71.2 23.9 59.6 21.7 22.3 134 46.9 27.1 12.4 14.9 14.1
RMSE (mm/h) 1-10 mm/h 1.63 1.67 1.97 2.88 2.86 2.88 3.01 2.96 3.19 3.38 1.79 1.84 1.77 1.70 2.21
< 1 mm/h 0.90 0.58 0.59 0.96 1.28 1.15 1.10 0.83 1.73 2.22 0.63 0.59 0.59 0.58 0.58
> 10 mm/h 100 100 100 96 90 92 93 94 96 93 100 100 100 100 100
RMSE (%) 1-10 mm/h 112 99 98 94 116 106 95 87 117 201 93 97 98 95 98
< 1 mm/h 157 99 100 175 222 200 190 144 334 384 108 99 100 97 99
> 10 mm/h - - -0.05 0.08 0.00 0.10 0.02 0.12 -0.03 -0.07 -0.09 0.30 - - -0.03
CC 1-10 mm/h 0.00 -0.01 0.00 0.14 0.10 0.13 0.09 0.09 0.08 0.05 0.04 0.10 0.04 -0.04 0.04
< 1 mm/h 0.05 -0.03 0.02 -0.01 0.03 0.02 0.04 0.04 -0.01 0.01 0.01 -0.01 0.01 0.03 0.03
POD ≥ 0.25 mm/h 0.17 0.03 0.05 0.30 0.30 0.33 0.41 0.48 0.14 0.20 0.16 0.07 0.04 0.08 0.05
FAR ≥ 0.25 mm/h 0.75 0.80 0.70 0.88 0.70 0.74 0.75 0.66 0.86 0.59 0.76 0.80 0.79 0.86 0.82
CSI ≥ 0.25 mm/h 0.11 0.03 0.05 0.09 0.18 0.17 0.18 0.25 0.07 0.15 0.11 0.06 0.03 0.05 0.04
Reference Data
The PR-OBS-3 v.1.4 rain rate product has been validated against automatic rain gauges data. Polish
network of automatic rain gauges consists of 430 posts located all over the country, however, the
network density increases in the Southern Poland, where the flood danger is very high. Each post is
equipped with two gauges: heated and non-heated, what enables some quality control of data. For
validation purposes, readings from both gauges were compared in order to eliminate the cases of
clogged instruments. If both gauges worked properly, higher values was taken (automatic RG are known
to underestimate the real precipitation).
The measurements time resolution is 10 minutes, what allows estimating the rain rate with reasonable
quality, especially for stratiform rainfalls. The ground rain rate (in mm/h) was calculated from 10
minute cumulative values from the timeslot closest to the satellite overpass assuming that the real
precipitation rate was constant within that time span.
In order to combine satellite products with rain gauges data, the following simple method was applied.
For each satellite pixels, the automatic posts situated within that pixel were found. If more than one rain
gauge were found within one satellite pixel, the ground rain rate value was calculated as a mean of all
rain gauges measurements within that pixel.
Results
Following the methodology agreed in the H-SAF precipitation validation group, both continuous and
categorical statistics were calculated on the monthly mean basis for three precipitation categories:
- category 1: >10 mm/h,
- category 2: 1-10 mm/h,
- category 3: