Precipitation and cloud forecasts in two HIRLAM versions

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Precipitation and cloud forecasts in two HIRLAM versions (RCR and H 635) in September

Precipitation and cloud forecasts in two HIRLAM versions (RCR and H 635) in September 2004 • Kalle Eerola • Finnish Meteorological Institute • kalle. eerola@fmi. fi 20/10/2021 1

Contents 1. Introduction 2. Precipitation verification of European LAMs from U. K. Met. Off.

Contents 1. Introduction 2. Precipitation verification of European LAMs from U. K. Met. Off. 3. Comparison of RCR and H 635 forecasts 1. Differences between RCR and H 635 2. Accumulated monthly precipitation 3. Verification of T 2 m, Rh 2 m and cloudiness 4. Conclusions 20/10/2021 2

Precipitation verification of European LAMs by U. K. Met. Off • • Area: United

Precipitation verification of European LAMs by U. K. Met. Off • • Area: United Kingdom Against UK NIMPROD rain-fall composite Time: since January 2004 LAMs – – Aladin (France) Hirlam RCR (FMI) Lokall MODEL (DWD) Met. Off. unified mesoscale Model (U. K. ) • Scores – FBI - Frequency Bias Index • >1 overestimates, < 1 underestimates – ETS – Equitable Threat Score • =0 for random hit, =1 for perfect forecast 20/10/2021 3

FBI and ETS over UK for different thresholds • Results since January 2004 •

FBI and ETS over UK for different thresholds • Results since January 2004 • Hirlam = RCR at FMI (~6. 3. 0) • Frequency bias: – All model overestimate weak precipitation – Hirlam underestimates moderate/strong precipitation – Other models overestimate them • Equitable Threat Score – Hirlam: very weak rain: score lower – Skill decreases in all model as threshold increases 20/10/2021 4

Results of tests between RCR and Hirlam 6. 3. 5 • RCR – Regular

Results of tests between RCR and Hirlam 6. 3. 5 • RCR – Regular Cycle with the Reference – RCR = Hirlam 6. 2. 1 + changes ≈ Hirlam 6. 3. 0 – Earlier no one ran with reference no good idea how the reference works – Operational at FMI • • • Resolution 0. 2º x 0. 2º, 40 levels Archived at ECMWF, available for Hirlam community Products available for Hirlam community in near-real time on WEB -pages Available a mod. set to run parallel to RCR (will be included into the reference ) Possible to test against RCR products A control run already exists 20/10/2021 5

Main differences and similarities between RCR and H 635 • Similarities – H 635

Main differences and similarities between RCR and H 635 • Similarities – H 635 uses same observations, boundaries, boundary strategies and extra observations as RCR – Same area and resolution in horizontal and vertical • Differences – – – – New release of HIRVDA (mainly technical) Modified water vapour saturation below freezing First Aid Kit by Laura Rontu Tanquay-Ritchie scheme of temperature in SL-scheme Rotation of surface stress vector Physics-dynamics coupling Modified melting of soil ice Smoothed topography 20/10/2021 6

Monthly precipitation: Europe • • Rather similar in RCR and H 635, compares well

Monthly precipitation: Europe • • Rather similar in RCR and H 635, compares well to gauge-based analysis GPCC = The Global Precipitation Climatology Centre H 635 more precipitation than RCR (Scandinavia, Alps, …) H 635 has smoother structure • Smoothed orography • Tanquay-Ritchie SL changes • Dynamics-physics coupling 20/10/2021 7

Monthly precipitation: Scandinavia • • • Rainy month in Finland: observed is 100300% of

Monthly precipitation: Scandinavia • • • Rainy month in Finland: observed is 100300% of the normal In H 635 more precipitation, fits better to observed (southern Finland, Kainuu), H 635 has smoother sctructure 20/10/2021 8

Convective part of precipitation • • As earlier, the 24 -48 hour forecasts, ie.

Convective part of precipitation • • As earlier, the 24 -48 hour forecasts, ie. second day In H 635 the structure is much smoother than in RCRa – Smoothed orography – Tanquay-Ritchie SL changes – Dynamics-physics coupling • Especially over the mountains 20/10/2021 9

Conclusion from precipitation • H 635 produces more precipitation than RCR • The accumulated

Conclusion from precipitation • H 635 produces more precipitation than RCR • The accumulated monthly precipitation has a smoother structure in H 635 than in RCR • Convective part is especially smoother 20/10/2021 10

Diurnal variation in surface (near-)parameters 20/10/2021 11

Diurnal variation in surface (near-)parameters 20/10/2021 11

Station verification for EWGLAM stations • T 2 m – At night almost all

Station verification for EWGLAM stations • T 2 m – At night almost all negative bias removed – During day negative bias reduced • RH 2 m – Diurnal cycle in RCRa – In H 635 almost unbiased 20/10/2021 12

At night: Bias of T 2 m, Rh 2 m and cloudiness 20/10/2021 13

At night: Bias of T 2 m, Rh 2 m and cloudiness 20/10/2021 13

During day: Bias of T 2 m, Rh 2 m and cloudiness 20/10/2021 14

During day: Bias of T 2 m, Rh 2 m and cloudiness 20/10/2021 14

Conclusions I • U. K. Met. Off. Precipitation verification – Frequency bias: • All

Conclusions I • U. K. Met. Off. Precipitation verification – Frequency bias: • All model overestimate weak precipitation • Hirlam underestimates moderate/strong precipitation, while other models overestimate them – Equitable Threat Score • Hirlam: very weak rain: score lower • Skill decreases in all model as threshold increases • Accumulated monthly precipitation – H 635 produces more precipitation than RCR – The accumulated monthly precipitation has a smoother structure in H 635 than in RCR – Convective part is especially smoother 20/10/2021 15

Conclusions II • At Night • • • T 2 m: negative bias decreased,

Conclusions II • At Night • • • T 2 m: negative bias decreased, even positive bias in some are Rh 2 m: Positive bias (too humid) decreased Too dry: southern Europe and America Cloudiness. Difficult to interpret the results Daytime • T 2 m: • • – – Cold bias still is in H 635 but it is reduced In America almost disappeared Rh 2 m: • Positive (too humid bias has reduced in central and northern Europe • Even too much in southern Europe, where in H 635 is now negative bias Cloudiness: difficult to interpret 20/10/2021 16