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CHR-workshop june 2003
Regional climate modelling for the Rhine basin
Regional climate modelling for the Rhine basin
Bart van den Hurk (KNMI)
With contributions fromGeert Lenderink, Erik van Meijgaard,
Jules Beersma (KNMI)Hendrik Buiteveld (RIZA)
CHR-workshop june 2003
ContentsContents
• Regional climate modelling at KNMI• Verification and improvement of the
RCM• Precipitation statistics over the Rhine
basin (present-day climate)• Conclusions
CHR-workshop june 2003
Regional climate modellingat KNMI
Regional climate modellingat KNMI
• Regional climate scenarios– Statistical downscaling (Buishand, Beersma et al)– Weather generators– Since late 2001: RACMO = HIRLAM + ECMWF
physical package• RegioKlim project
– Verification and improvement of RACMO– Production of scenarios– Participation in (inter)national projects
(PRUDENCE, new FP6-projects, ICES/KIS)
CHR-workshop june 2003
Verification andimprovement of RACMO
Verification andimprovement of RACMO
• Free interior,atmospheric forcing atlateral boundaries
• 15yr simulation with“observed” boundaries(ERA15, 1979-1993)
• Verification using synops data, ECA-data and meteorologicalanalyses
CHR-workshop june 2003
Basic problems of control version of RACMO (1)
Basic problems of control version of RACMO (1)
• Summertime dry warm bias
Bias compared to all ±220 ECA-stations
CHR-workshop june 2003
SolutionSolution
• Increase hydrological memory of thesoil– Deeper soil reservoir– Smaller sensitivity of transpiration to soil
water content
CHR-workshop june 2003
Basic problems of control version of RACMO (2)
Basic problems of control version of RACMO (2)
• Too much precipitation overmountains
CHR-workshop june 2003
SolutionSolution
• Filter orography and reducehorizontal diffusion
CHR-workshop june 2003
Basic problems of control version of RACMO (3)
Basic problems of control version of RACMO (3)
• Different synoptic patterns compared to driving meteorological fields
ERA15 RACMO
CHR-workshop june 2003
SolutionSolution
• Optimize procedure to importinformation in lateral boundary
ERA15RACMO
CHR-workshop june 2003
Precipitation over the Rhine basin (present-day climate)Precipitation over the Rhine basin (present-day climate)
gredients (1)CHR daily precipitation data1961-1995 over 134 sub-catchmentsAggregated to RACMO model grid (69gridpoints)
102
107
109 104 103
105106
115113
110
108112
111
114
66
34
50171849 47
24
1648 12
7
8 6
2
3
1
7675
72
7174
73
100
97
70
69
68
96
92
67 6564
33
35
37 36
93
94
9
10
78
79
8081
82
84
83
4
5
11
13
1415
19
20
21
22
23
25
28
29
26
27
8886
85
87
3231
30
45
44
39
38
40
46
51
52
55
5453
56
57
60 6263
42
41
59
43
61
58
90
9899
10195
91
77
89
116117
121
129
130
126
131133
132
118
119
120
128
127
123124
125
122
134
100 0 100 Kilometer
N
HBV DistrictsErftLahnLippeLower RhineMainMiddle RhineMoselleNaheNeckarRuhrSchweizSiegUpper RhineUpper Rhine 2
GewässerStaatsgrenze
• In–
–
CHR-workshop june 2003
Precipitation over the Rhine basin (present-day climate)Precipitation over the Rhine basin (present-day climate)
• Ingredients (2)– ERA15: RACMO
reference simulation(1979-1993)
– HadAM3: RACMOsimulation with modifications control climate (1961-1990, only first 10yrsanalysed) (included in PRUDENCE project)
CHR-workshop june 2003
Average annual cycle aggregated over domain
Average annual cycle aggregated over domain
CHR-workshop june 2003
Average annual cycle aggregated over domain
Average annual cycle aggregated over domain
Effect of soil drying
CHR-workshop june 2003
Pattern of average bias inHadAM run
Pattern of average bias inHadAM run
Lower areas surrounded by mountains too dry, mountains too wet
CHR-workshop june 2003
Autocorrelation of timeseries
Autocorrelation of timeseries
CHR-workshop june 2003
Frequency distribution ofareal averages
Frequency distribution ofareal averages
1 day sum
5 day sum
CHR-workshop june 2003
Individual eventsIndividual events
CHR-workshop june 2003
Pattern correlationPattern correlation
• Correlate daily field on day t with day t+lag
• For each lag, average correlations for all events
• Expresses temporal consistency ofspatial patterns
CHR-workshop june 2003
Pattern correlationPattern correlation
Strong persistence ofprecipitation patterns,partially by (too) strongorographic control in themodels
CHR-workshop june 2003
Pattern correlationPattern correlation
CHR-workshop june 2003
ConclusionsConclusions
• Model modifications improved hydrological cycle and its seasonal time scale
• Average annual cycle of precipitation well simulated, but systematic spatial errors
• Small overestimation of light events on 1-day timescale
• Small underestimation of extreme events on5-day timescale