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MMM Executive Summary Choose a Section... PPWS (Prediction of Precipitating Weather Systems) CaSPP (Cloud and Surface Processes and Parameterizations)

Overview

The mission of the Mesoscale and Microscale Meteorology (MMM) Division is to advance the understanding of the mesoscale and microscale aspects of weather and climate and to apply this knowledge to benefit society. MMM establishes its priorities through an evaluation of its program against the priorities of its five-year Science Plan (http://www.mmm.ucar.edu/products/stratplan.html) and the NCAR Strategic Plan (http://www.ncar.ucar.edu/stratplan/plan.pdf), as well as against those of national and international research programs such as the USWRP and the USGCRP.

Approximately half of the MMM science program is USWRP-related and is focused on the goal of improving the ability to forecast weather events. This part of the program is organized under the theme Prediction of Precipitating Weather Systems (PPWS). The other half is focused on problems related to understanding the physics of mesoscale and microscale processes, the way these processes interact with larger scales, and how the processes can be represented in models where they are not resolved. This part of the MMM program is organized under the theme Cloud and Surface Processes and Parameterizations (CaSPP).

Research

Prediction of Precipitating Weather Systems (top)

The main goal of the PPWS, one of the division’s two overarching scientific themes, is to advance the understanding and prediction of significant precipitation events in order to substantially reduce forecast errors toward the limits of predictability. Within the PPWS theme there are four separate programs as described below.

Weather Research and Forecasting Model

The goal of this program is to develop an advanced mesoscale forecast and assimilation system, and to accelerate research advances into operations. The WRF model is being developed as a collaborative effort with NOAA/NCEP, NOAA/FSL, AFWA, NRL, CAP at U of OK, and the FAA. The work carried out in FY2004 included further collaborations with the UK Met Office, U of Munich (Germany), Yonsei U (Seoul, Korea), U of CA at Davis, Hebrew U of Jerusalem (Israel), Pacific Northwest National Laboratory, Iowa State U, San Francisco State U, U of WA, and Ohio State U. Interdivisional collaborations included ASP, RAP and CGD.

Highlight:

Recent results show that WRF forecasts exhibit realistic structure and intensity from coarse initial data without bogusing; hurricane track forecasts have accuracy similar to or better than the current operational models; and, moving nested grids yield high-resolution forecasts with greatly enhanced efficiency (smaller fine-grid domains).

Mesoscale Data Assimilation

The goal of this program is to determine optimal use of mesoscale observations for accurate precipitation forecasts. The WRF data assimilation research has many applications within NCAR and has been advanced through collaborations with the Danish Meteorological Institute, the Taiwan Civil Aeronautics Administration and Central Weather Bureau, the India National Center for Medium-Range Weather Forecasts, Seoul National U, the Shanghai Meteorological Bureau, Ohio State U, A.M. Boukhov Institute of Atmospheric Physics (Moscow), Texas A&M, CIMMs/U of OK, NOAA/NSSL, U of WA, and U of CO. Cross divisional collaboration included CGD, ESIG, RAP, and COSMIC.

Highlight:

Recent highlights were the assimilation of GPS RO data from CHAMP and SAC-C mission for a case of intense cyclone over the Ross Sea; and, the assimilation of ~50 GPS RO soundings over a two-day period with MM5 4DVAR which produced significant impact on the prediction of the cyclone.

Prediction and Predictability

The goal of this program is to estimate the duration of useful skill in mesoscale precipitation forecasts and identify key skill-limiting physical processes. Collaborations in support of this program involve researchers at Nanjing U (China), Texas A&M, and U of WA. These FY2004 activities included collaboration with TAMU, Nanjing U/China, NOAA, RAP, and ASP.

Highlight:

Recent progress has been made in understanding flows with many scales. In the case of flows with many scales, small-scale errors may grow rapidly and contaminate larger scales in finite time. Such systems may have intrinsic, finite limits of predictability (i.e., at some point, improved initial conditions provide little or no benefit to forecasts). Scaling suggests finite predictability when E(k) is less steep than k-3, and recent progress has confirmed relation of predictability to E(k) for 2D turbulence.

Life Cycles of Precipitating Weather Systems

The goal of this program is to understand life cycles of precipitation events, and to assess implications for predictability, data-assimilation and model physics. Collaborations included U of NE (Lincoln), U of KS, CRN (Italy), NOAA/ETL, Yale, SUNY, U of S. Florida, and Simon Fraser U (Canada) as well as interdivisional collaboration with RAP and ASP.

Highlight:

The main findings of recent research are that mini baroclinic waves grow from convection and have a strong effect on rainfall organization; surface penetration has implications for T.C.’s; and, varied environments exist, including strong shear.

Cloud and Surface Processes and Parameterizations (top)

The main goal of CaSPP, the second of MMM’s two overarching scientific themes, is to quantify the large-scale effect of mesoscale and microscale processes and to develop physically based methods to account for these effects in large-scale models. Within the CaSPP theme are five separate programs as described below. A research highlight for each program of research is included.

Surface-Atmosphere Interactions

The goal of this program is to understand the influences of surface heterogeneity and surface-atmosphere interactions. Collaborations in support of this program include CU, USGS, U of MT, Penn State, Woods Hole, TAMU, CNdR/Italy, Trento U/Italy, U of IL, Iowa State, NASA, U of Miami, OSU, ACD, RAP, and ATD. Each year MMM scientists are involved in large-scale field campaigns that further the program objectives. For example, in FY2004 scientists played a leading role in the Ocean Horizontal Array Turbulence Study (OHATS) that took place off the coast of Martha’s Vineyard (www.mmm.ucar.edu/research/ surface/hats.html#ohats).

Highlight:

Collaboration between NCAR, Woods Hole Oceanographic Institute and Penn. State University has led to the collection of 2000 hours of turbulence and wave data from 18 sonic anemometers and 3 laser altimeters and to the construction of subfilter-scale (LES) fluxes in the marine surface layer. The investigators examined the couplings between atmospheric turbulence and surface gravity waves, using the OHATS and HATS databases to build new subgrid scale parameterizations for LES (large-eddy simulations).

Planetary Boundary Layer

The goal of this program is to determine how boundary-layer clouds affect climate. Collaborations that furthered this program’s goals include UCLA, Utrecht U/Netherlands, U of WY, U of OK, Drexel U, CU, LANL, USCA, Seoul U/Korea, ACD, ATD, ASP, and RAP.

Highlight:

A recent research highlight includes a joint study involving MMM, Woods Hole Oceanographic Institute and University of California, Los Angeles. Finding were that sea state can modulate magnitude and orientation of mean wind and momentum flux. LES results were obtained for a neutral PBL with swell (phase speed c = 12.5 m/s) moving parallel to geostrophic wind Ug = 5 m/s; the surface layer wind component normal to geostrophic wind is negative instead of positive; surface layer wind component along geostrophic wind has low-level jet at 20m height; and, weak shear results in loss of turbulence energy in the PBL.

Multiscale Convective Cloud Systems and Waves

The goal of this program is to determine cloud effects on atmospheric and ocean circulations. Numerous collaborations took place in FY2004 in support of this program including those with Iowa State U, ECMWF, LANL, Cranfield U in UK, Institute of Earth Envionment at Chinese Academy of Sciences, Osaka U (Japan), U of Florida, NCMRWF in New Delhi (India), NASA/Langley, UK Met Office, CSU, Nasa/Goddard, Japan Agency for Marine-Earth Science and Technology, Institute of Meteorology and Water Management (Poland), and interdivisionally with SCD, ASP, RAP, and CGD.

Highlight:

QBO, the dominant variability of the equatorial stratosphere, has so far eluded complete understanding. Plumb & McEwan’s (1978) laboratory analogue demonstrated the basic mechanism of a mean-flow development, but its relevance to the atmospheric QBO has been criticized. Direct numerical simulation shows the lab experiment is relevant but needs reinterpretation in terms of wave-wave-mean flow interaction, critical layer formation and subsequent wave breaking.

Cloud-Microphysics and Small-Scale Processes

The goals of this research are to understand ice phase latent heating in hurricanes, to develop parameterizations of ice microphysics for use in hurricane weather forecast models, and to develop algorithms for deriving ice microphysical properties from multi-wavelength radars. Collaborations include the NOAA Hurricane Research Labs, University of Maryland, and NASA JPL.

Highlight:

During the past year, a group of cloud physicists met frequently to design a series of field programs, laboratory experiments and modeling activities to make progress in the area of ice initiation. An internationally-represented steering committee was formed, and the first “Ice Initiation Workshop” with 64 participants from 32 institutions and 5 countries was conducted over two days in June. An outline for an NSF Scientific Overview Document (SOD) was also developed.

Chemistry, Aerosols, and Dynamics Interactions Research

The goal of this program is to understand interactions between atmospheric dynamics, aerosols, and chemistry at meso- and cloud scales. Work in this program includes collaborations with NOAA FSL, MIT, Penn State, Seoul U/Korea, ACD, ASP, and CGD.

Highlight:

Recent studies on the effect of boundary layer processes on chemical species distributions showed cloud chemistry enhances the segregation of reacting species. These results were compared with Dutch LES (large-eddy simulations), and turbulent dispersion of scalars was examined. Another recent research study focused on the WRF-AqChem, a coupled meteorology and multi-phase chemistry model. This study led to the implementation of aqueous chemistry into the WRF model, and an intercomparison of convective cloud chemistry models.

Table of Contents | Director's Message | Executive Summary | MMM Achievements
Education and Outreach | Community Service | Awards | Publications | People | ASR 2004 Home