Validation of storm surge forecasts for the Dutch coast

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                                                       Validation of
                                                        storm surge
                                                         forecasts
                                                       for the Dutch
                                                           coast
                                                                    Hans de Vries


                                                           KNMI, Weather Service

                                                       Research and Development

                                                              Hans.de.Vries@knmi.nl

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Overview
                                                                                         GLAMEPS




                                                                                 Harmonie




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Validation aspects
Models                                              Parameter


 › Atmosphere                                         › Astronomical tide

 › Storm surge                                        › Surge



                                                    Situation
Fit for purpose
                                                      › Day-to-day forecasts
                                                      › Extreme events


Model stage
                                                    Type of forecast
 › Model setup and calibration
                                                      › Deterministic forecasts
 › Operational forecasts
                                                      › Probability forecasts




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Observations
In-situ

Atmosphere             SYNOP/SHIP/TEMP
                       Aircraft data

Storm surge            Tide gauges

                                                   Caveat


                                                     › Accuracy
Remote sensing                                       › Representativeness

Atmosphere             Scatterometer
                       Radar
                       Lidar

Storm surge            Altimeter




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Models
Atmosphere

KNMI Hirlam Limited area                     tf   <    48 h               Deterministic


ECMWF IFS           Global                   tf   <   240 h               Ensemble




Storm surge

WAQUA/DCSM                                                                 Dutch Continental Shelf Model
 › Rijkswaterstaat
 › Deltares                              Version 5 (8 km, 1998)                       Version 6 (2 km)

 › KNMI




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Model setup and calibration
Astronomical tide




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Model setup and calibration
Storm surge


                                       H7.0                                                                                     H7.2


             1.0                                                                                           1.0



             0.5                                                                                           0.5
  Hwaq [m]




                                                                                                Hwaq [m]
             0.0                                                                                           0.0



             -0.5                                                                                          -0.5



             -1.0                                                                                          -1.0
 29                                                                                           26
                                                            Hoek van Holland                                                                         Hoek van Holland
  9                                                                                            8
                                                        High tides 12 < tf ≤ 24                                                                  High tides 12 < tf ≤ 24
  3                                                                                            2
  1                 -1.0       -0.5     0.0       0.5              1.0                         1                  -1.0   -0.5    0.0       0.5              1.0
  0                                    Hobs [m]                                                0                                Hobs [m]




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Model setup and calibration
Storm surge event




                            Hoek van Holland: oper 2007110812                                               Hoek van Holland: H72 2007110812


                    3                                                                               3




                    2                                                                               2
    Sea level [m]




                                                                                    Sea level [m]
                    1                                                                               1




                    0                                                                               0




                        0         12          24       36           48                                  0         12         24       36       48
                                           t [h]                                                                          t [h]
                                            f                                                                              f




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Operational forecasts: Verication
                                             Hoek van Holland: High tides
                                                                                            -3 < t ≤ 3 (Kalman)
                                                                                                  f
                                                                                             3 < t ≤ 9 (Kalman)
                                                                                                  f
                                                                                            15 < t ≤ 21
                                                                                                   f
           0.20                                                                             27 < t ≤ 33
                                                                                                   f
                                                                                            39 < t ≤ 45
                                                                                                   f



           0.15
  σH [m]




           0.10



           0.05



           0.00
              1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010



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Operational forecasts: Verication
                                                  Hoek van Holland: High tides
                                                                                                  -3 < t ≤ 3 (Kalman)
                                                                                                        f
                                                                                                   3 < t ≤ 9 (Kalman)
               0.20                                                                                     f
                                                                                                  15 < t ≤ 21
                                                                                                         f
                                                                                                  27 < t ≤ 33
                                                                                                         f
                                                                                                  39 < t ≤ 45
                                                                                                         f
               0.15


               0.10
 bias ∆H [m]




               0.05


               0.00


               -0.05


               -0.10


                  1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010



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Probability forecasts

                                                   Hoek van Holland: Probability forecasts from 2007110600 run
                     4


                     3                                                                                                                                                   AP
                                                                                                                                                                         GP


                                                                                                                                                                         WP

                     2                                                                                                                                                   VP
                                                                                                                                                                         IP
     Sea level [m]




                     1


                     0


                     -1

                      Tue 06 Nov      Wed 07 Nov     Thu 08 Nov   Fri 09 Nov       Sat 10 Nov   Sun 11 Nov   Mon 12 Nov   Tue 13 Nov   Wed 14 Nov   Thu 15 Nov   Fri 16 Nov
                        00:00           00:00          00:00         00:00            00:00        00:00       00:00        00:00        00:00        00:00         00:00


                          0              24             48          72               96          120           144          168          192          216         240
                                                                                                tf [h]


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Probability forecasts

                                                   Hoek van Holland: Probability forecasts from 2007110600 run
                     4


                     3                                                                                                                                                   AP
                                                                                                                                                                         GP


                                                                                                                                                                         WP

                     2                                                                                                                                                   VP
                                                                                                                                                                         IP
     Sea level [m]




                     1


                     0


   97%
   93%               -1
   90%
   75%
   50%
                      Tue 06 Nov      Wed 07 Nov     Thu 08 Nov   Fri 09 Nov       Sat 10 Nov   Sun 11 Nov   Mon 12 Nov   Tue 13 Nov   Wed 14 Nov   Thu 15 Nov   Fri 16 Nov
   25%                  00:00           00:00          00:00         00:00            00:00        00:00       00:00        00:00        00:00        00:00         00:00
   10%
    7%                    0              24             48          72               96          120           144          168          192          216         240
    3%
                                                                                                tf [h]


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Probability forecasts

                                        RH for Hoek van Holland                                                             CRH for Hoek van Holland
                                                                                                                  100
                             14


                             12                                                                                    80
    observed frequency [%]




                                                                                         observed frequency [%]
                             10
                                                                                                                   60
                             8


                             6                                                                                     40


                             4
                                                                                                                   20
                             2

                             0                                                                                      0
                                  0      10       20      30     40         50                                          0    20      40        60       80   100
                                                   bin number                                                                     EPS probability [%]


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Probability forecasts
Brier skill scores


                                    Den Helder Kansen-EPS0 tf = 48 .. 84                                                       Den Helder Kansen-EPS0 tf = 192 .. 240


                            60                                                                                          60
    Brier Skill Score [%]




                                                                                                Brier Skill Score [%]
                            40                                                                                          40




                            20                                                                                          20




                            0                                                                                           0



                                 -100    -50       0          50    100    150                                               -100   -50     0          50    100     150
                                                       Surge [cm]                                                                               Surge [cm]




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Probability forecasts
                                                Hoek van Holland +2.20 m
               240



               192



               144
      tf [h]




                96



                48



                0
                      0                   20          40              60                    80                  100
                                                   Exceedance threshold [%]

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Probability forecasts
                                                                          Hoek van Holland +2.20 m
               240
                                                    5
                                    35




                                                        1
                                                            3

                                                        1
                                       88
                              367




               192
                                            7




               144
      tf [h]




                                                                                                5
                                                                                                1    3         1



                96                                                              5
                                                                10




                                                                                         3


                                                                                                           7


                48
                       1538




                                                                      10
                                 367
                               88




                                                                                                                        5




                                                                                                                                 1
                                                                                                                             3
                                                                                                1
                               5




                                                3                     7
                0
                      0                                          20              40              60                    80                  100
                                                                              Exceedance threshold [%]

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                                                                  Thank you




G G G G   Coastal Model Validation   Storm surge forecasts for the Dutch coast   18  20 Nov 2009   17