Kain-Fritsch/Rasch-Kristjanson in Hirlam
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Transcript of Kain-Fritsch/Rasch-Kristjanson in Hirlam
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 2004.– 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: 20-50 km – Operational at SMHI since 2003– Hirlam reference as option since September, 2004
Kain-Fritsch Convection
Hirlam modifications to the new schemesKain-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 schemesRasch-Kristjansson large scale condensation
Hirlam modifications to the new schemesRasch-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 schemesDiagnostic 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
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/RK STR
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 Cloud covercover
LWPLWP
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 6.2.0
• 23 Dec- 7 Jan 2000
• 1–15 May 2001• 1-15 Aug 2001• 15-30 Sep 1994• 1- 31 Oct 2002
NWP mode at 20km: Parallel runs
- Comparison of reference STRACO and KFRK- Scores against observations
Comparisons against EWGLAM soundings
Temperature Relative Humidity
Similar scores excepted in the humidity field
REF
KF/RK
Comparisons against SYNOP stations
MSL Pressure Cloud Cover
STRKF/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/RK REF
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
The End