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Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986.

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Presentation on theme: "Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986."— Presentation transcript:

1 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986

2 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Arne Melsom, met.no

3 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Conclusions taken from the presentation from the first OPNet-meeting: A preliminary finding is that the present ensemble underestimates variability The presentation was sketchy and not very focussed =>much work to do!

4 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Model set-up 20 km model 4 km model (10 member ensemble) air/sea momentum & heat fluxes from ECMWF products ice concentrations by met.no’s ice service climatology as the 20km model OBC 8 tidal constituents added to the 4km BC climatological runoff

5 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Data for validation Vardø Rørvik Gimsøy NW Bear Isl. W Fugløya- Bear Isl. Vardø N Hydrography (IMR, WOD) Sea levels

6 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Vardø Rørvik Stationσ obs σ mod-obs Vardø0.610.21 Rørvik0.760.25 Sea level raw data/results Stationσ obs σ mod-obs Vardø0.19 Rørvik0.160.23 de-tided data/results mean SSH corr(ΔSL Vardø, ΔSL Rørvik ) = 0.67

7 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 IMR hydrographic transects TransectCruises/ year Stations/ cruise Gimsøy NW214 Bear Isl. W113 Fugløya – Bear Isl. 620 Vardø N.422

8 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Transect/sourcebiasσ Gimsøy NW-0.401.73 Bear Isl. W 0.261.79 Fugløya – Bear Isl. 0.711.40 Vardø N. 1.001.28 World Ocean Datab. 0.651.53 Transect/sourcebiasσ Gimsøy NW-0.130.35 Bear Isl. W-0.450.30 Fugløya – Bear Isl.-0.240.25 Vardø N.-0.210.17 World Ocean Datab.-0.260.50 Salinity (0, 10, 20, 30m) Temperature (0, 10, 20, 30m)

9 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Transect#obs (1986) 0 m20 m50 m Gimsøy NW4 3.613.565.97 Bear Isl. W1420.227.966.17 Fugløya – Bear Isl.99 1.821.922.95 Fugløya – Bear Isl. 8-10 39 1.441.451.92 Vardø N.39 1.311.423.01 Salinity

10 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 S mod -S clim ; S clim >34.8, surface …the model is salt-deprived; Why? nesting problem? No! …problem orginates from 20km model bias

11 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Probability density functions (Aug-Nov) salinity (0, 10, 20, 30m)

12 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 temperature (0, 10, 20, 30m)

13 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Ensemble variability & flow instabilities Let y m be a result from ensemble member m; split: y m = y + y + y m ′ Then, (y m -y) 2 = y 2 + σ y ′ 2 and let r = σ y ′ 2 / (y m -y ) 2 ^~ ~ ^ ~

14 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Sea ice and ensemble variability

15 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Results from ranking assume e.g. S obs (x 1,y 1,z 1,t 1 ) = 34.85 S e.1 (x 1,y 1,z 1,t 1 ) = 34.81 S e.2 (x 1,y 1,z 1,t 1 ) = 35.05 S e.3 (x 1,y 1,z 1,t 1 ) = 34.95 S e.4 (x 1,y 1,z 1,t 1 ) = 34.87 34.8 34.9 35.0 35.1 1 2 3 4 5 …this observation has rank 2 Transect/source Gimsøy NW28 Bear Isl. W56 Fugløya – Bear Isl.432 Vardø N.220 World Ocean Datab.11836 #observations

16 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Transect/sourcef { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/2156267/8/slides/slide_15.jpg", "name": "Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Transect/sourcef

17 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 Summary Sea level:major fronts above continental slope high-frequency variability OK low-frequency variability poor Salinity:model values are too low model range is too low very high cost function in Atlantic Water Temperature: warm bias in model (generally) moderate cost functions Ensemble:low ensemble variability high flow instability impact off Lofoten

18 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986

19 Norwegian Meteorological Institute met.noValidation of a 4km model ensemble for 1986 time axis ‘+12 forcing’: time axis ‘+24 forcing’: Construction of ensemble From atmospheric forecasts models: an. +12 +24 +36 +48 +60 +72 +84 +96 time axis an. +12 +24 +36 +48 +60 +72 +84 +96 12hr later: an. +12 +24 +36 +48 +60 +72 +84 +96 12+12hr later:.


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