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Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology Meteo. Swiss

Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology Meteo. Swiss A. Topographic radiation correction in COSMO: gridscale or subgridscale? B. COSMO-2: convection resolving or convection inhibiting model? Matteo Buzzi Meteo. Swiss COSMO GM, WG 3, 15. 09. 2008

A. Topographic radiation correction: gridscale or subgridscale? Radiation in complex terrain • • •

A. Topographic radiation correction: gridscale or subgridscale? Radiation in complex terrain • • • Default COSMO radiation scheme (Ritter&Geleyn, 1992): topographic effects on radiation are not considered COSMO-2 (2. 2 km) and COSMO-7 (6. 6 km) @ Meteo. Swiss: grid-scale radiation correction (Buzzi, 2008) Next step: compare the grid-scale and subgrid-scale radiation correction over a longer period • Preliminary results: 2 winter weeks (12 -25. 12. 2007) COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 2

Two radiation correction procedures model gridcell Müller and Scherrer (2005), Buzzi (2008) Grid scale

Two radiation correction procedures model gridcell Müller and Scherrer (2005), Buzzi (2008) Grid scale (COSMO-2 2. 2 km, COSMO-7 6. 6 km) : COSMO Topo slope angle, slope aspect skyview, horizon COSMO run correction factors Subgrid scale (COSMO-2 330 m, COSMO-7 1 km): DEM topo slope angle, slope aspect skyview, horizon COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch correction factors skyview aggregation COSMO run 3

Test suite • • 2 winter weeks: 12 -25. 12. 2007 COSMO-2 with own

Test suite • • 2 winter weeks: 12 -25. 12. 2007 COSMO-2 with own assimilation cycle COSMO-7 with own assimilation cycle Compared the operational suite with gridscale radiation correction and the testsuite with subgridscale radiation correction COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 4

Results - 2 m temperature COSMO-2 COSMO-7 COSMO GM, WG 3, Recent testsuites at

Results - 2 m temperature COSMO-2 COSMO-7 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 5

2 m dew point COSMO-2 COSMO-7 COSMO GM, WG 3, Recent testsuites at Meteo.

2 m dew point COSMO-2 COSMO-7 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 6

RMSE 2 m temperature: summary [°C] N stn Subgrid 2@alps Grid 2@alps Subgrid Grid

RMSE 2 m temperature: summary [°C] N stn Subgrid [email protected] Grid [email protected] Subgrid Grid [email protected] N stn Subgrid [email protected] Grid [email protected] All 491 3. 06 3. 03 3. 22 3. 21 1339 2. 26 0 -500 283 2. 64 2. 69 1032 2. 15 5001000 120 3. 71 3. 68 3. 85 3. 82 193 2. 94 10001500 39 4. 01 3. 93 4. 15 56 2. 98 2. 96 15002000 27 3. 08 3. 05 3. 74 3. 76 33 3. 37 3. 45 20004000 22 2. 08 2. 11 3. 00 3. 02 25 2. 32 2 correction options are virtually equivalent, no significant differences Stations with positive and negative effects are in balance Stations are located near gridpoints with low impact COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 7

Mean difference 12 -25. 12. 2007 subgrid-grid, direct shortwave radiation 09 UTC COSMO-2 [min,

Mean difference 12 -25. 12. 2007 subgrid-grid, direct shortwave radiation 09 UTC COSMO-2 [min, max]=[-204, 223] COSMO-7 14 UTC [min, max]=[-102, 84] COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch [W/m 2] 8

Mean difference 12 -25. 12. 2007 subgrid-grid, diffuse downward radiation 09 UTC COSMO-2 [min,

Mean difference 12 -25. 12. 2007 subgrid-grid, diffuse downward radiation 09 UTC COSMO-2 [min, max]=[-12, 15] COSMO-7 14 UTC [min, max]=[-11, 11] COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch [W/m 2] 9

Mean difference 12 -25. 12. 2007 subgrid-grid, longwave downward radiation 09 UTC COSMO-2 [min,

Mean difference 12 -25. 12. 2007 subgrid-grid, longwave downward radiation 09 UTC COSMO-2 [min, max]=[-11, 18] COSMO-7 14 UTC [min, max]=[-10, 14] COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch [W/m 2] 10

Mean difference 12 -25. 12. 2007 subgrid-grid, shortwave balance 09 UTC COSMO-2 [min, max]=[-146,

Mean difference 12 -25. 12. 2007 subgrid-grid, shortwave balance 09 UTC COSMO-2 [min, max]=[-146, 164] COSMO-7 14 UTC [min, max]=[-67, 57] COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch [W/m 2] 11

Mean difference 12 -25. 12. 2007 subgrid-grid, surface temperature 09 UTC COSMO-2 [min, max]=[-7.

Mean difference 12 -25. 12. 2007 subgrid-grid, surface temperature 09 UTC COSMO-2 [min, max]=[-7. 6, 8. 5] COSMO-7 14 UTC [min, max]=[-4. 9, 4. 7] COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch [°C] 12

Mean difference 12 -25. 12. 2007 subgrid-grid, 2 m temperature 09 UTC COSMO-2 [min,

Mean difference 12 -25. 12. 2007 subgrid-grid, 2 m temperature 09 UTC COSMO-2 [min, max]=[-2. 3, 3. 1] COSMO-7 14 UTC [min, max]=[-1. 5, 1. 4] COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch °C 13

Conclusions and outlook • • • Verification differences are very small • But: impact

Conclusions and outlook • • • Verification differences are very small • But: impact on the surface radiation components and on surface temperature are significant • Stations are probably not really representative for the entire alpine region, compensation effects • Stable conditions: upward transport of information reduced • Differences at the surface can be relevant for snow melting • Is not possible to indicate the winner! Gridscale correction has an important practical advantage: • Easy to be operated: long preprocessing calculations for computation of external parameters can be avoided Additional verification is necessary • 2 summer weeks • Radiation verification with satellite data and ASRB stations COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 14

B. COSMO-2: Convection resolving or convection inhibiting model? mm/24 h COSMO-2 COSMO GM, WG

B. COSMO-2: Convection resolving or convection inhibiting model? mm/24 h COSMO-2 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch RADAR 15

But COSMO-7 is not really better… mm/24 h COSMO-7 COSMO-2 COSMO GM, WG 3,

But COSMO-7 is not really better… mm/24 h COSMO-7 COSMO-2 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch RADAR 16

Why is COSMO-2 so bad? Some hypothesis. . . Beyond of predictability issues. .

Why is COSMO-2 so bad? Some hypothesis. . . Beyond of predictability issues. . . • We are faced in these situations (no strong dynamical forcing) with “non-equilibrium convection cases” (Craig et al. ) • Limiting factor is the trigger (CIN overcoming) and not the forcing (generation of CAPE) • PBL and soil humidity distribution, local circulations, topography effects, small scale surface moisture convergence, PBL profiles near the surface • Independent shallow convection and turbulence parameterization (communication between scales) • LHN is the rescuer, but has always a positive impact? Problem is probably located in the PBL COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 17

Parallel test-suites - July 2008 • • Motivation: • Try something in order to

Parallel test-suites - July 2008 • • Motivation: • Try something in order to save model reputation • Past tests: COSMO model is very sensitive to changes of the turbulence scheme parameter tur_len (Koller, 2008; Seifert, 2007) • Smaller values reduce turbulent mixing, increase gridscale fluxes Testsuites: • Modified asymptotic turbulent length scale (tur_len) • Change of settings in the statistical cloud scheme: • 1. opr: clc_diag=0. 75, qcrit=4. 0 • 2. and 3. test: clc_diag=0. 5, qcrit=1. 6 6 days: all 3 configurations (2 -8. 7. 2008): fuzzy verification for 00 runs 30 days: configuration 1 and 2 (1 -30. 7. 2008): fuzzy verification for 00 runs COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 18

Fuzzy Verification on coarser scales than model scale: “Do not require a point wise

Fuzzy Verification on coarser scales than model scale: “Do not require a point wise match!“ Method Raw Data Fuzzyfication Referece: radar composite Score Example result Average X Upscaling X X X Equitable threat score x X X X x Fractional coverage Fraction Skill Score (Roberts and Lean, 2005) X X X x X X X Skill score with reference to worst forecast x bad COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch good 19

Fuzzy verification 2 -8. 07. 2008 1. COSMO-2 500 2. COSMO-2 250 COSMO GM,

Fuzzy verification 2 -8. 07. 2008 1. COSMO-2 500 2. COSMO-2 250 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 3. COSMO-2 150 20

Tests vs operational 2 -8. 07. 2008 2. COSMO-2 250 vs 1. 500 3.

Tests vs operational 2 -8. 07. 2008 2. COSMO-2 250 vs 1. 500 3. COSMO-2 150 vs 1. 500 TEST better operational better COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 21

July 2008 – 00 UTC RUNS 1. COSMO-2 OPR 500 2. COSMO-2 test 250

July 2008 – 00 UTC RUNS 1. COSMO-2 OPR 500 2. COSMO-2 test 250 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Difference 22 Matteo. Buzzi[at]meteoswiss. ch 1. COSMO-2 operational better 2. COSMO-2 test better

July 2008 – all runs with 3 h cut-off 1. COSMO-2 OPR 500 2.

July 2008 – all runs with 3 h cut-off 1. COSMO-2 OPR 500 2. COSMO-2 test 250 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Difference 23 Matteo. Buzzi[at]meteoswiss. ch 1. COSMO-2 operational better 2. COSMO-2 test better

Conclusions and outlook • • Reduction of the asymptotic mixing length: • No wonder

Conclusions and outlook • • Reduction of the asymptotic mixing length: • No wonder results! We still have a trigger problem. • Test 1 with 150 m: • Too many gridpoints react • Small deterioration from small to medium scales and from small to medium thresholds • Test 2 with 250 m: • small improvement at medium to large scales and medium to large thresholds • Optimal value should be close to 250 m Outlook: • three case studies have been selected: further investigations (soil moisture, vertical profiles, role of the LHN, shallow convection, SBL) • Verification of other meteorological parameters COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 24

Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology Meteo. Swiss

Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology Meteo. Swiss Thank you for your attention!

Wind speed and direction COSMO-2 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss

Wind speed and direction COSMO-2 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 26

Wind speed and direction COSMO-7 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss

Wind speed and direction COSMO-7 COSMO GM, WG 3, Recent testsuites at Meteo. Swiss Matteo. Buzzi[at]meteoswiss. ch 27