Kain-Fritsch/Rasch-Kristjanson in Hirlam Javier Calvo With contributions from Karl-Ivar Ivarsson & Colin Jones

Outline of the talk Moist physics schemes in HIRLAM Reference is STRACO (Based on Sundqvist) New/optional is Kain-Fritsch & Rasch-Kristjansson Background of new moist physics components Review of the results of the new schemes in Hirlam Conclusions

Moist physics schemes for HIRLAM (1) Operational scheme is called STRACO (Sass, 2002) –Sundquist type (Kuo convection and Sundquist microphysics) –Smooth transitions convective-large scale regimes –Treatment of shallow convection –Tuning for high horizontal resolutions (5-10 km) –Improvement of diagnostic cloud scheme (statistical type) –Most HIRLAM components developed with this scheme as reference. Long operational use.

Moist physics schemes for HIRLAM (2) A scheme based on Kain-Fritsch convection and Rasch/Kristjansson is in the HIRLAM reference system since September –Three new components: Kain-Fritsch convection Rasch-Kristjansson condensation Diagnostic cloud fraction based on RH

Background of the new schemes Mostly developed and used within MM5 community –Specially suitable for mesoscale middle-latitudes simulations (10-30 km resolution) including severe phenomena. Operational use over the USA (up to 10 km resolution) –MM5 Model –Eta Model –WRF Model Bechtold’s version of KF –MESO-NH: Extensively tested. Many cases studies from synoptic scale to CRM scales. Realistic systems –ARPEGE/ALADIN. Not able to improve the reference convection Hirlam –RCA, Rossby Center Regional Climate Model: km –Operational at SMHI since 2003 –Hirlam reference as option since September, 2004 Kain-Fritsch Convection

Hirlam modifications to the new schemes Kain-Fritsch Convection Based on new version of KF (Kain, JAM, 2004): –Implementation similar to the one in WRF model In HIRLAM, implemented by Colin Jones for RCA model –Several updates mainly concerning shallow convection

Based on Rasch and Kristjansson, J. Climate, 1998 Developed for the Community Climate Model (CAM3) where is the reference since 2004 First introduced in Hirlam by Odegard, 1999 (HNL 33) Background of the new schemes Rasch-Kristjansson large scale condensation

Hirlam modifications to the new schemes Rasch-Kristjansson large scale condensation The scheme is divided in two parts: –Condensation parameterization (water vapor ↔ condensate) following Sundquist ideas but completely recoded. –Bulk microphysics (condensate to precipitation) with and approach similar to CRM formulae. Different physical processes are well separated Updates and improvements more easy For HIRLAM mainly tuning updates (Mainly by C. Jones). –Inclusion of Hirlam thermodynamics –Make the autoconversion process independent of model’s vertical resolution

Hirlam modifications to the new schemes Diagnostic cloud fraction Large scale clouds basically depend on Relative Humidity. Initially based on Slingo (1987) but completely recoded. Convective clouds are function of convective mass-flux following Su and Krueguer (1991). Shallow clouds are based on Albrecht (1981) as described by Jones and Sánchez (2002): –Depend on resolved RH and Cu updrafts water vapor and condensate. –There is a memory of shallow clouds that may generate precipitation through large scale microphysics.

Single Column Model case studies Model’s climate: Hadley circulation Rossby Center Climate model. Complete model case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme and observations. Operational use at SMHI. Review of the results of the new moist physics (KFRK) in Hirlam

Single Column Model case studies EUROCS Project Model’s climate: Hadley circulation Rossby Center Climate model. Complete model case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme and observations. Operational use at SMHI.

EUROCS tried to improve the representation of clouds in GCM and NWP models. –Identify systematic errors in the models. –Design ideal cases based on observations. –Compare SCM and CRM with observations –Evaluate improvements in the GCM. –Philosophy similar to GCSS intercomparisons except that EUROCS also includes simulations with the complete GCMs. EUROCS project SCM cases from EUROCS in which HIRLAM participated Diurnal cycle of Sc over ocean Diurnal cycle of shallow Cu over land Diurnal cycle of Deep convection over land.

KF/RK and STRACO show similar behaviour : Lack of or insuficient cloud top entrainment: Drizzle acts to control Liquid Water: Sensitivity to microphysics formulation. Diurnal Cycle of Sc over ocean KF/RK STRACO LES Evolution of Liquid water

Passive cloud formulation for KFRK As active clouds tipically not larger than 5% it is very important to include the ‘passive clouds’ which have a significant impact on radiation LES STRACO KF/RK Diurnal Cycle of Shallow Cu over land Evolution of Liquid water The mass-flux approach (KF) describes better the growth and daily evolution of the clouds.

Review of the results of the new moist physics (KFRK) in Hirlam Single Column Model case studies EUROCS Project Model’s climate: Hadley circulation Rossby Center Climate model. Complete model case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme and observations. Operational use at SMHI.

Hirlam run in NWP mode Compute monthly means of H+24 forecasts Compare with satellite observations Comparison with other models Representation of the Hadley Circulation: ‘Climate’ of KF/RK and STRACO

Cross sections along the Hadley Circulation

Precipitation: Comparison with TRMM satellite KF/RKSTR TRMM

Precipitation: Comparison with TRMM satellite Both Hirlam schemes show too much precipitation in the Sc and Shallow Cu regions

KF/RK STR ERA ECMWF H+6 Cloud Cover: Comparison with ERA ECMWF H+6

KF/RK STR Cloud cover Cloud cover LWP LWP Deficiencies on cloud cover and LWP: specially underestimation in the Sc regions and overestimationi n the sahllow Cu

Review of the results of the new moist physics (KFRK) in Hirlam Single Column Model case studies EUROCS Project Model’s climate: Hadley circulation Rossby Center Climate model. Complete model case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme and observations. Operational use at SMHI.

Hirlam-Rossby Center Climate Model (Willen, Jones and Wyser, 2004) RCA3 44km 24L ERA40 Seasonal precipitation from RCA compared to observations: the model captures the amplitude and spatial distribution of the precipitation for all seasons

Review of the results of the new moist physics (KFRK) in Hirlam Single Column Model case studies EUROCS Project Model’s climate: Hadley circulation Rossby Center Climate model. Case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme and observations. Operational use at SMHI.

Cases Studies Niemela and Fortelius, 2002 (HNL 41): –Frontal system. Experiment at 5.5 km resolutions and 40L KFRK shows stronger updradrafts and downdrafts than STRACO No clear adventage on using one of the schemes. Finkele, 2001 (HNL 37): –Rapidly deeping cyclone from FASTEX –Experiments at 24 and 12 km –More realistic cloud patterns with KFRK. McGraph and Finkele, 2001 (HNL 38): –Parallel runs of STRACO and KFRK –Small differences in standar scores except cloud cover –Rapidly deepening cyclones more better represented in KFRK.

A typhoon case study (COMPARE III) H+72 integration using different initial conditions. Comparison with observations and other models Errors in the track prediction are small Little impact of the resolution on the track forecast

Typhoon case study: Intensity Very rapid intensification (100 hPa/ 3 days) - Very sensitive to initial conditions and model resolution - Kain-Fritsch performed quite well for this case (BOLAM and HIRLAM model) KF/RK STR

Typhoon case study: STRACO precipitation (H+60) 50 km 20 km

Typhoon case study: KF/RK precipitation (H+60) 50 km 20 km

Precipitation as function of model resolution in the core region As expected, in the inner area (200 km around the typhoon center), convective precipitation decreases as resolution increases whereas large scale precipitation increases. Total precipitation increases increasing model resolution.

Single Column case studies. Model’s climate: Hadley circulation Case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme. Operational use at SMHI. Review of the results of the new moist physics (KFRK) in Hirlam

5 test periods on different seasons (3 months). Using Hirlam Dec- 7 Jan –15 May Aug Sep Oct 2002 NWP mode at 20km: Parallel runs - Comparison of reference STRACO and KFRK - Scores against observations

Comparisons against EWGLAM soundings TemperatureRelative Humidity Similar scores excepted in the humidity field REF KF/RK

Comparisons against SYNOP stations MSL Pressure Cloud Cover STR KF/RK Only differences in MSLP and cloud cover: Small deterioration of MSLP Some improvemnet in cloud cover

MSLP RMS against its own analysis (all periods) KF/RKREF

MSLP RMS against its analysis (all periods) KF/RK REF

Precipitation against SYNOPs (all periods) SpainEWGLAM

October 2002 precipitation as seen by SYNOP stations and High-resolution climatic stations

Upscale high-resolution observations to model resolution

October 2002 precipitation: impact of the resolution

October 2002 precipitation:KFRK vs REF-STRACO at 0.2 KF/RK REF

Single Column case studies. Model’s climate: Hadley circulation Case studies: Mainly severe weather Parallel runs: comparison with reference STRACO moist scheme. Operational experience at SMHI. Review of the results of the new moist physics (KFRK) in Hirlam

KF/RK is in the SMHI operational suit since Dec, 2002 –At 0.4 and 0.2 resolutions with 40 levels –Experimental 0.1 resolution. Only a few experiments comparing KF/RK with the reference STRACO: so no conclusion on this. Duty forecasters seem to be very satisfied with the new scheme, specially for convective situations. Validation of the new operational suite gave a significant improvement of the humidity forecasts (but several new modules incorporated) It seems that Hirlam is able to add value to ECMWF forecasts in terms of clouds and precipitation. Operational experience at SMHI (from Karl-Ivarsson, personal comunication)

Operational experience at SMHI (Karl-Ivarsson, personal comunication) Comparison of Hirlam 0.2, Hirlam 0.1 and ECMWF model for the period July, 7-Ago,17, 2004: True Skill Statistic

Experiment at 10 km: ppt acc. 6hr H+06

Experiment at 10 km: ppt acc. 6hr H+12

Experiment at 10 km: ppt acc. 6hr H+18

Experiment at 10 km: ppt acc. 6hr H+24

High-resolution observations

The new moist physics scheme based on Kain-Fritsch convection and Rasch-Kristjansson large scale condensation has been tested in Hirlam. In terms of standard scores no big difference with reference STRACO scheme a part from: –Slight deterioration in MSLP probably caused by a tendency to over- intensification of cyclonic systems. –Slight improvement in cloud cover –Improvement in the humidity profiles –Similar scores of precipitation: STRACO better for small ppt amounts (< 1 mm/day) KF/RK probably better for ppt 3-30 mm/day More clear improvement in southern regions probably linked to the larger number of convective situations. From case studies it seems that KFRK tends to produce more realistic cloud and precipitation patterns. Conclusions

Operational experience at SMHI very satisfactory KFRK takes about 20 % more computer time than the reference STRACO. –Still pending the vectorization of the code: external asistance is planned. Some clearly identified problems: –Excess of drizzle. –Cloud cover formulation Statistical cloud scheme Moist turbulence We have started testing KFRK at 10 km resolutions. In the near future we should evaluate its performance at lower resolutions. –Probably further tuning is needed Conclusions

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