Date post: | 02-Jan-2016 |
Category: |
Documents |
Upload: | candace-wood |
View: | 221 times |
Download: | 3 times |
Verification of the distributions
Chiara Marsigli
ARPA-SIM - HydroMeteorological Service of Emilia-Romagna
Bologna, Italy
Methodology
Station observation
Grid point forecast
the verification area is covered with boxes of fixed size
the distributions of both forecast and observed values falling in each box are considered
verification is made by comparing (in terms of usual scores) the parameters of the two distributions, e.g.:
• average value
• maximum value
• 50th percentile (median)
• 90th percentile
Aims method suitable for precipitation suitable for high-resolution models permit to exploit a dense network of sparse observations (raingauges) enable comparison between models with different horizontal resolution assess the forecast quality in a way helpful for the forecaster:
which is the skill of the model in predicting the average precipitation amount over an area of 50x50 km2 (e.g. a basin)? which is the skill of the model in predicting a high precipitation value located anywhere within an area of 50x50 km2?
13 May 2005 case
point (standard) verification
thresholds: 1., 5., 10., 20., 30., 50. mm = 0.04, 0.2, 0.39, 0.79, 1.18, 1.97 inchesn. points: 301101; n. occurrences: 11506, 3247, 1449,
544, 235, 46
average values - 0.5 x 0.5 ° boxes
thresholds: 1., 5., 10., 20. mm = 0.04, 0.2, 0.39, 0.79 inchesn. points: 3080; n. occurrences: 92,
26, 10, 2
maximum values - 0.5 x 0.5 ° boxes
thresholds: 1., 5., 10., 20., 30., 50. mm = 0.04, 0.2, 0.39, 0.79, 1.18, 1.97 inchesn. points: 3080; n. occurrences: 257, 85, 50,
22, 15, 5
90th percentile values - 0.5 x 0.5 ° boxes
thresholds: 1., 5., 10., 20., 30., 50. mm = 0.04, 0.2, 0.39, 0.79, 1.18, 1.97 inchesn. points: 3080; n. occurrences: 154, 45, 25,
9, 4, 1
01 June 2005 case
point (standard) verification
thresholds: 1., 5., 10., 20., 30., 50. mm = 0.04, 0.2, 0.39, 0.79, 1.18, 1.97 inchesn. points: 301101; n. occurrences: 18360, 2622, 950,
402, 257, 124
average values - 0.5 x 0.5 ° boxes
thresholds: 1., 5., 10., 20. mm = 0.04, 0.2, 0.39, 0.79 inchesn. points: 3080; n. occurrences: 132,
16, 4, 3
maximum values - 0.5 x 0.5 ° boxes
thresholds: 1., 5., 10., 20., 30., 50. mm = 0.04, 0.2, 0.39, 0.79, 1.18, 1.97 inchesn. points: 3080; n. occurrences: 390, 119,
55, 23, 8, 5
90th percentile values - 0.5 x 0.5 ° boxes
thresholds: 1., 5., 10., 20., 30., 50. mm = 0.04, 0.2, 0.39, 0.79, 1.18, 1.97 inchesn. points: 3080; n. occurrences: 242, 42, 15,
4, 4, 3