Dear Colleague,
The 7th World Meteorological Organization (WMO) Cloud Modeling Workshop
is planned for July 14-17, 2008, in Cozumel, Mexico, immediately after the
International Conference on Clouds and Precipitation (ICCP).
Broadly, the goals of the workshop are to provide an assessment of the state of the art of cloud modeling, to identify key gaps in the ability of models to represent clouds, and to suggest potential pathways for model improvement. The strategy is similar to past WMO cloud modeling workshops that have utilized observationally-derived case studies to provide a framework for the model intercomparison. The focus is on three key areas: 1) deep convection, 2) stratiform mixed-phase clouds, and 3) cloud chemistry. While representation of cloud microphysics in models and interactions of the microphysics with other model components have received recent attention in other frameworks (e.g., GEWEX Cloud System Study; GCSS), these issues have had comparatively less focus in the three areas listed above. A brief overview of the case studies is given at the end of this letter. Details of the cases can be found at the "Workshop Cases" link on workshop web page.
We plan to divide the workshop into plenary sessions and working group meetings. Plenary sessions will include a brief overview of the cases (at the beginning of the workshop), summary from working groups (at the end of the workshop), and contributed papers (15-30 minutes depending on the number of papers submitted). We invite all workshop participants to consider presenting results of their research in the form of a contributed paper. Papers pertaining to the general area of cloud physics and cloud modeling are welcome. Additional time will be available during the working group meetings to discuss specific results from the workshop case studies. To submit a paper, please send an abstract to Hugh Morrison (morrison@ucar.edu) no later than April 20, 2008.
Working Groups: As in previous workshops, working groups will be organized around the cases considered and they will meet in parallel. We expect that most of the workshop participants will select a case closest to their scientific interests, perform model simulations and submit results as instructed, and contribute to the working group meetings during the workshop. PLEASE NOTE THAT IT IS NOT NECESSARY TO SIMULATE ONE OF THE CASE STUDIES TO ATTEND THE WORKSHOP, AND ALSO THAT IT IS POSSIBLE TO CONTRIBUTE TO THE WORKSHOP WITHOUT PHYSICALLY ATTENDING IT.
A social event and group dinner is also planned (details to follow).
We ask that all workshop partipants please register by clicking on the "Registration" tab, and following the instructions. A registration fee of $100 is requested. Other information on the workshop, including details of the case studies, can be accessed from the workshop home page above.
For questions, please contact:
Hugh Morrison (morrison@ucar.edu)
or
Greg Thompson (gthompsn@ucar.edu)
We look forward to a productive meeting and hope to see you in Mexico in July 2008.
Hugh Morrison and Greg Thompson (NCAR), Co-Chairs
1. Cloud chemistry. Two cases have been identified from ICARTT measurements conducted from the Canadian Convair 580 while based out of Cleveland, OH, in July- August 2004. A number of trace gas, aerosol, and cloud parameters were measured. These include aerosol particle chemistry with an AMS and a PILS, cloud droplet residuals with an AMS downstream of a CVI, and bulk cloudwater chemistry. Of particular interest may be how models simulate the processing of nitrogen and sulphur through cloud, how carbonyl compounds are scavenged by cloud, and the effects of cloud microphysics on chemistry. The two cases are as follows:
1) Chemical processing by boundary layer cumulus downwind of Chicago region. Clouds and air below cloud were sampled along the 86W meridian and then along the 84W meridian between about 40.5 and 42.6 N with westerly winds. A large plume impacting the clouds was encountered along both lines downwind of Chicago. This case may be suited for comparison of cloud chemistry in regional-scale models. Case leaders: Richard Leaitch, Wanmin Gong, Anne Marie MacDonald.
2) Chemical processing by towering cumulus. Measurements were taken below cloud and at multiple levels within the cloud. This case may be suitable for cloud-scale and parcel models. Case leaders: Richard Leaitch, Anne Marie MacDonald, Wanmin Gong. .......................................................................
2. Mixed-phase stratiform clouds. Two cases have been identified:
1) Persistent mixed-phase arctic stratus observed during the SHEBA field experiment during May 1998. Single-layer, boundary layer mixed-phase cloud with cloud top temperature of ~ -20 C, weak turbulent surface fluxes over a sea-ice-covered surface. Extensive cloud and thermodynamic measurements from aircraft and ground-based instruments. Primary focus is on the ability of models to maintain this long-lived mixedphase cloud, despite the weak forcing and cold temperatures. Likely to be a joint case with GCSS Polar Cloud Working Group. Suitable for single-column, cloud-resolving, and LES models. Case leader: Hugh Morrison.
2) 2D orographic precipitation from a mixed-phase cloud system based on idealized and real cases. For the idealized case, the focus is on orographic precipitation resulting from stable upslope flow over a bell-shaped mountain (hydrostatic wave or blocked flow conditions). The real case is based on an event in the European Alps during March 2004. Initial thermodynamic and microphysical (CCN/aerosol spectra) data are taken from field campaign observations. Measurements of precipitation, radar reflectivity, and cloud microphysics (droplet concentration, liquid/ice water content) are available for evaluation of the models. The primary focus is on the partitioning of condensate between the liquid and the ice-phase and the amount and distribution of precipitation. Furthermore, estimates of the indirect aerosol effect on mixed-phase clouds and precipitation can be compared among the models. Case leaders: Andreas Muhlbauer and Ulrike Lohmann. .......................................................................
3. Deep convection. Two cases have been identified:
1) Midlatitude squall line case(s) based on observations near Oklahoma City. Two candidate squall lines are being considered: 13 Jun 2002 (IHOP field study) and 12-13 May 2005. Both have polarimetric radar data and detailed Oklahoma mesonet observations in addition to the standard suite of wind profilers, radiosondes, etc. The latter case also provides video disdrometer data used to create observed rain drop size distributions during a passing mature squall line. Idealized 2D and fully 3D cases are likely to be developed from one or both of these events. Primary focus is on surface precipitation, cold pool characteristics and storm morphology (e.g., development of the trailing stratiform rain region). Case leaders: Greg Thompson and Ed Brandes.
2) Supercell-type deep convection with either cold (< 5C) or warm (>15 C) cloud base. Cold-based case occurred near Greeley, Colorado during post cold-front upslope initiation scenario. Warm-based case occurred near Oklahoma City in a dry line initiation scenario. Available observations are from polarimetric radar, dual-doppler radar, WSR- 88D, and rawinsonde. Hydrometeor characteristics based on fuzzy logic interpretation of polarimetric data following Straka et al. (2000; JAM). Primary focus is on rain development, recycling, and rear and forward flank cold pool strength, with a secondary focus on hail development. Case leader: Jerry Straka.
Principle organizers:
Hugh Morrison (NCAR)
Greg Thompson (NCAR)
Wojciech Grabowski (NCAR)
Richard Leaitch (Environment Canada)
Ulrike Lohmann (ETH-Zurich)
Andreas Muhlbauer (ETH-Zurich)
Roy Rasmussen (NCAR)
Jerry Straka (Univ. of Oklahoma)
Junhua Zhang (Environment Canada) Special thanks to Graciela Raga (UNAM,
Mexico) for help on the logistics.