Presentation is loading. Please wait.

Presentation is loading. Please wait.

Sensitivity to the PBL and convective schemes in forecasts with CAM along the Pacific Cross-section Cécile Hannay, Jeff Kiehl, Dave Williamson, Jerry Olson,

Published byJack Jones Modified over 9 years ago

Similar presentations

Presentation on theme: "Sensitivity to the PBL and convective schemes in forecasts with CAM along the Pacific Cross-section Cécile Hannay, Jeff Kiehl, Dave Williamson, Jerry Olson,"— Presentation transcript:

1 Sensitivity to the PBL and convective schemes in forecasts with CAM along the Pacific Cross-section Cécile Hannay, Jeff Kiehl, Dave Williamson, Jerry Olson, Jim Hack, Richard Neale and Chris Bretherton* National Center for Atmospheric Research, Boulder *University of Washington, Seattle Joint GCSS-GPCI/BLCL-RICO Workshop, NASA/GISS, 18-21 September 2006

2 Motivation Using forecast runs to test new parameterizations during the model development ? Is the GCSS-Pacific Cross-Section a good candidate to do this ?

3 Outline Models: PBL and convective schemes Cross-section: climate runs versus observations. Forecast runs settings Forecast errors along the cross-section Examples: 3 cloud regimes – ITCZ region – Trade-Cumulus – Stratocumulus Conclusion

4 Models: PBL and convective schemes CAM - Boundary layer: Holtslag-Boville (1993) - Shallow convection: Hack (1993) - Deep convection: Zhang-McFarlane (1995) CAM-UW (Chris Bretherton) - Turbulence scheme: Grenier-Bretherton (2001) includes explicit entrainment at the top of the PBL - Shallow convection: cloud-base mass flux based on surface TKE and convection inhibition near cloud base CAM-dilute (Richard Neale) - Deep convection: parcels are diluted by environment air

5 Observations along the cross-section (JJA 1998) SWCFLWCF LWP Low cloud Mid/high cloud Precipitation CERES SSM/I ISCCP, D2GPCPISCCP, D2

6 Model versus observations SWCFLWCF LWP Low cloud Mid/high cloud Precipitation CERES SSM/I ISCCP, D2 GPCP ISCCP, D2 --- Obs --- CAM --- CAM-UW --- CAM-dilute

7 Forecast run specification Strategy If the model is initialized realistically, we assume the error comes from the parameterizations deficiencies. Advantages Full feedback  SCM Deterministic  statistical Look at process level Limitations Accuracy of the atmospheric state ? Initialize realistically ERA40 reanalysis CAM 5-day forecast Starting daily at 00 UT Observations ERA40

8 Forecast errors and climate errors (CAM-ERA40) Cloud regimes => range of error structures Climate bias appears very quickly in CAM Climate error ~ Forecast error at day 5 Forecast T error (K), day 1Forecast T error (K), day 5Climate T error (K), JJA1998 Forecast q error (g/kg), day 1Forecast q error (g/kg), day 5Climate q error (g/kg), JJA1998

9 Forecast temperature errors at day 5 CAM-UW Some improvement in the cumulus region CAM-dilute Reduces T bias near ITCZ Error increases above 300 mb and in the lower troposphere. Changes in regions where the deep convection is not active CAM CAM-UW CAM-dilute

10 Select a range of cloud regimes and forecast errors 3 locations ITCZStratocumulusTrade cumulus Forecast T error at day 5, CAM

11 ITCZ regime: forecast T error (JJA 1998) CAM CAM-dilute ITCZ region: very sensitive to the deep convective scheme

12 Total tendencyAdvective tendencyPhysics tendency ITCZ regime: Temperature equation --- CAM --- CAM-dilute

13 Select a range of cloud regimes and forecast errors 3 locations ITCZStratocumulusTrade cumulus Forecast T error at day 5, CAM

14 Stratocumulus: moisture and PBL (JJA 1998) PBL heightSpecific humidity CAM CAM-UW Stronger daily cyclePBL collapses day 0 day 1 day 2 day 5

15 Stratocumulus: timeseries of T and q error T CAM -T ERA40 q CAM -q ERA40

16 Stratocumulus: q equation (single forecast) CAM CAM-UW q Advective tendency Physics tendency

17 Stratocumulus regime (Physics terms) CAM CAM-UW PBL tendency Shallow tendency Prognostics cloud water tendency

18 Conclusion CAM forecasts allows for diagnosing model errors in the different cloud regimes. Climate bias appears very quickly in CAM – Where deep convection is active, error is set within 1 day – 5-day errors are comparable to the mean climate errors. New schemes: CAM-UW and CAM-dilute -CAM-dilute: improves the warm bias in upper troposphere, but cold bias increases in lower troposphere and near top of the model. -CAM-UW: does not change the error structure but CAM-UW operates very differently than CAM at the process level. Difficult to decide what is causing the errors in such a coupled system => need observations. => Comparison along the A-train

19

20

21 Observations along the cross-section SWCFLWCF LWP Low cloud Mid/high cloud Precipitation CERES SSM/I ISCCP, D1GPCPISCCP, D1

22 Model versus observations SWCFLWCF LWP Low cloud Mid/high cloud Precipitation CERES SSM/I ISCCP, D1 GPCP ISCCP, D1 --- Obs --- CAM --- CAM-UW --- CAM-dilute

23 Cumulus regime: Forecast q errors CAM CAM-UW

24 Cumulus regime: moisture budget terms 2 PBL/ShCu schemes operate in very different way.

25 ITCZ regime: Precipitation (JJA 1998) - GPCP Dataset Daily precipitation - CAM Loses water very quickly during day 1. - CAM-dilute Precipitation increases during day 1.

26 ITCZ regime: Temperature equation

27 Stratocumulus regime (Q, CLOUD, CLDLIQ)

Download ppt "Sensitivity to the PBL and convective schemes in forecasts with CAM along the Pacific Cross-section Cécile Hannay, Jeff Kiehl, Dave Williamson, Jerry Olson,"

Similar presentations

Page 1© Crown copyright 2007 Initial tendencies of cloud regimes in the Met Office Unified Model Keith Williams and Malcolm Brooks Met Office, Hadley Centre.

Page 1© Crown copyright 2007 Initial tendencies of cloud regimes in the Met Office Unified Model Keith Williams and Malcolm Brooks Met Office, Hadley Centre.
Www.met.rdg.ac.uk/~swr06iab Moisture Transport in Baroclinic Waves Ian Boutle a, Stephen Belcher a, Bob Plant a Bob Beare b, Andy Brown c 24 April 2014.

Moisture Transport in Baroclinic Waves Ian Boutle a, Stephen Belcher a, Bob Plant a Bob Beare b, Andy Brown c 24 April 2014.
An overview of recent CAM developments Contributors: Chris Bretherton, Bill Collins, Andrew Conley, Brian Eaton, Andrew Gettelman, Steve Ghan, Cécile Hannay,

An overview of recent CAM developments Contributors: Chris Bretherton, Bill Collins, Andrew Conley, Brian Eaton, Andrew Gettelman, Steve Ghan, Cécile Hannay,
Joint GABLS-GLASS/LoCo workshop, 19-21 September 2004, De Bilt, Netherlands Interactions of the land-surface with the atmospheric boundary layer: Single.

Joint GABLS-GLASS/LoCo workshop, September 2004, De Bilt, Netherlands Interactions of the land-surface with the atmospheric boundary layer: Single.
Evaluating parameterized variables in the Community Atmospheric Model along the GCSS Pacific cross-section during YOTC Cécile Hannay, Dave Williamson,

Evaluating parameterized variables in the Community Atmospheric Model along the GCSS Pacific cross-section during YOTC Cécile Hannay, Dave Williamson,
Precipitation development; Warm and Cold clouds >0 ° C

Precipitation development; Warm and Cold clouds >0 ° C
Process-oriented MJO Simulation Diagnostic: Moisture Sensitivity of Simulated Convection Daehyun Kim 1, Prince Xavier 2, Eric Maloney 3, Matthew Wheeler.

Process-oriented MJO Simulation Diagnostic: Moisture Sensitivity of Simulated Convection Daehyun Kim 1, Prince Xavier 2, Eric Maloney 3, Matthew Wheeler.
The Problem of Parameterization in Numerical Models METEO 6030 Xuanli Li University of Utah Department of Meteorology Spring 2005.

The Problem of Parameterization in Numerical Models METEO 6030 Xuanli Li University of Utah Department of Meteorology Spring 2005.
Low-Latitude Cloud Feedbacks Climate Process Team – Findings and Experiences Chris Bretherton University of Washington, Seattle, USA Goal: Better simulation.

Low-Latitude Cloud Feedbacks Climate Process Team – Findings and Experiences Chris Bretherton University of Washington, Seattle, USA Goal: Better simulation.
GFDL Geophysical Fluid Dynamics GFDL Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey AM2 cloud sensitivity to details of convection and cloud.

GFDL Geophysical Fluid Dynamics GFDL Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey AM2 cloud sensitivity to details of convection and cloud.
The Radiative Budget of an Atmospheric Column in Tropical Western Pacific Zheng Liu Department of Atmospheric Science University of Washington.

The Radiative Budget of an Atmospheric Column in Tropical Western Pacific Zheng Liu Department of Atmospheric Science University of Washington.
Low-Latitude Cloud Feedbacks CPT Chris Bretherton University of Washington, Seattle, USA Goal: Better simulation and understanding of low- latitude [boundary.

Low-Latitude Cloud Feedbacks CPT Chris Bretherton University of Washington, Seattle, USA Goal: Better simulation and understanding of low- latitude [boundary.
A direct measure of entrainment David M. Romps Workshop on Large-Scale Circulations in Moist Convecting Atmospheres October 17, 2009.

A direct measure of entrainment David M. Romps Workshop on Large-Scale Circulations in Moist Convecting Atmospheres October 17, 2009.
The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology The Effect of Turbulence on Cloud Microstructure,

The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology The Effect of Turbulence on Cloud Microstructure,
IACETH Institute for Atmospheric and Climate Science Boundary Layer parametrisation in the climate model ECHAM5-HAM Colombe Siegenthaler - Le Drian, Peter.

IACETH Institute for Atmospheric and Climate Science Boundary Layer parametrisation in the climate model ECHAM5-HAM Colombe Siegenthaler - Le Drian, Peter.
Relationships between wind speed, humidity and precipitating shallow cumulus convection Louise Nuijens and Bjorn Stevens* UCLA - Department of Atmospheric.

Relationships between wind speed, humidity and precipitating shallow cumulus convection Louise Nuijens and Bjorn Stevens* UCLA - Department of Atmospheric.
National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California 1 GCSS Pacific Cross-section.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California 1 GCSS Pacific Cross-section.
The Radiative Budget of an Atmospheric Column in Tropical Western Pacific Zheng Liu 1 Thomas Ackerman 1,2, Sally McFarlane 2, Jim Mather 2, University.

The Radiative Budget of an Atmospheric Column in Tropical Western Pacific Zheng Liu 1 Thomas Ackerman 1,2, Sally McFarlane 2, Jim Mather 2, University.
Observational study of the transition from unbroken marine boundary layer stratocumulus to the shallow cumulus regime Irina Sandu and Bjorn Stevens Max-Planck-Institut.

Observational study of the transition from unbroken marine boundary layer stratocumulus to the shallow cumulus regime Irina Sandu and Bjorn Stevens Max-Planck-Institut.
Why are we here, at the UCLA Conf. Center in June 2005? What is the best way of representing the physics of the atmospheric PBL in weather and climate.

Why are we here, at the UCLA Conf. Center in June 2005? What is the best way of representing the physics of the atmospheric PBL in weather and climate.

Similar presentations

Ads by Google