MMM Executive Summary
Overview
The mission of the 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. The division carries
out this mission by focusing its research on the most important
and fundamental scientific themes in mesoscale and microscale meteorology
and by building strong collaborations with national and international
universities and research agencies. MMM places emphases on understanding
and forecasting weather and on evaluating the influence of meso-
and microscale processes on larger-scale phenomena. As explained
in NCAR’s Strategic Plan (Section 4.2.5), the division has
aligned its program with national and international programs, such
as the U.S. Weather Research Program (USWRP) and the Global Change
Research Program (GCRP).
In FY2003, significant progress was made in understanding and advancing
prediction and predictability, life cycles of precipitating weather
systems, mesoscale data assimilation, high-resolution weather research
and forecast model development, convective cloud systems, boundary-layer
clouds, surface-atmosphere interactions, and chemistry, aerosols,
and dynamics interactions research. As shown below, MMM was also
a pivotal player in a number of NCAR multidisciplinary initiatives
including Data Assimilation, Water Cycles across Scales, Wildland
Fire, Biogeosciences, and WRF/ESMF, all of which are described
in NCAR’s Strategic Plan (Section 5). The achievements described
below involved significant collaborations with the national and
international research communities.
These collaborations are described
in Table A, which can be accessed here or from each footnote.
Strategic Initiatives
MMM contributions to the Biogeosciences
Initiative were focused on surface heterogeneity. In
FY2003 MMM organized the datasets collected from the Niwot Ridge
pilot study and identified the surface
characteristics responsible for horizontal transport of CO2, where
it was found that drainage flows associated with topography are
the main CO2 transport mechanism. 1 Progress
was made on quantifying the relationship between surface heterogeneity
and horizontal transport
of CO2. This work will continue, as will the Niwot Ridge data analysis
to parameterize horizontal transport of CO2 using surface heterogeneity
information and the HYDRA. Work will also continue on monitoring
the wind profiles within the canopy layer at Niwot Ridge to investigate
seasonal variations in the relationship between surface heterogeneity
and CO2 transport.
MMM made substantial
contributions to the Wildland
Fire Collaboratory Initiative by developing
methods to incorporate GIS-based land use/vegetation
data into gridded numerical models for both fire
behavior and vegetation emissions and by applying this to a case
study. 2 Ultimately,
this development is needed to simulate real cases, as both fire
behavior and emissions models require up-to-date
quantitative information on vegetation genera and density. Simulations
were completed for the case study and presented at the Collaboratory
and the AMS Fire and Forest Meteorology Conference in December
2003. In addition, the specific user requirements and system specifications
for the DSS were defined and a system concept and diagram were
developed for the prototype under design. 3 Work
also included adapting and testing the fire model within the WRF
forecast system. The
Doppler on Wheels was deployed to a prescribed fire in Saskatchewan,
and rerouted to wildfires west of Glacier National Park in August
2003. 4 Data
were successfully collected and preliminary analyses were presented
at the AMS Fire and Forest Meteorology Conference.
Finally, reduced reaction mechanisms and methods for parameterizing
combustion processes in coupled atmosphere-fire models were developed 5 and
a paper was submitted to JAM on infrared imagery of crown fire
dynamics collected during FROSTFIRE.
Significant progress was made in the Water
Cycle Across Scales Initiative. Datasets for model testing
were completed including radar, RUC, and large-scale data during
July 1998, the period selected
for numerical simulation of sequences of precipitation over the
US continent. The design of model tests was completed, including
the initialization procedure, which was designed around NCEP global
analysis and MM5 data assimilation procedure with emphasis on the
ten-day period 19-29 July 1998. Initial two-dimensional simulations
including a control experiment and CRM sensitivity experiments
were completed to quantify the effect of terrain, large-scale forcing,
cloud-interactive radiation, and horizontally inhomogeneous thermodynamics,
results are currently being analyzed. This work was collaborative 6 and
included the development of the North American Monsoon field experiment
slated for summer 2004 with emphasis on numerical modeling
and use of future field data for model evaluation. 7
Within the WRF/ESMF Initiative,
a prototype ocean atmosphere coupling using the WRF
Advanced Software Framework was developed with support
from the DoD PET project. 8 Two
major milestones were met: the Preliminary ESMF Interface Specification
in April 2003 and the Interoperability
and Partial Compliance of JMC codes in July 2003. Progress was
also made on the design and implementation of common WRF/ESMF I/O
API supporting non-file-centric, scalable parallel I/O and coupling
functionality. 9
Specific accomplishments made in the Data
Assimilation Initiative include the completion of a prototype
of the Data Assimilation Research Testbed (DART). A variety of
ensemble filter assimilation
methods and a suite of models and tools for designing and analyzing
observing system simulation experiments are under development.
In addition, a prototype ensemble filter assimilation system for
synthetic observations with WRF was constructed. The division also
cosponsored the ASP summer 2003 colloquium on data assimilation
using DART software for exercises. Other work that began in FY2003
and will be continued into FY2004 includes fundamental research
on ensemble filtering methods and development of filters for NCEP's
Medium-Range Forecast (MRF) model and for GFDL's FMS models. Lastly,
a prototype of an ensemble filter assimilation system for the CCSM
CAM model was developed.
Research
Prediction and Predictability
The skill of precipitation forecasts
is limited by both practical and fundamental constraints. The
practical constraints include
the accuracy of the forecast model and the accuracy of its
initial conditions. The fundamental constraint is the finite limit
of
predictability, which arises from the influence of unresolved
scales. Research
this past year advanced understanding of the intrinsic limits
of predictability and the practical predictability of synoptic-scale
flows by examining analysis error statistics and their influence
on forecast-error growth.
Achievements include:
Scale Dependence of Predictability
- Improved understanding
of the scale dependence of predictability by exploring
the limits of predictability for precipitation
within the context of the Washington D.C. 2000 snowstorm
10 and generalized these results beyond a single case
study by considering the growth of small perturbations
to an
idealized, moist baroclinic wave developing in a
channel 11
Ensemble Forecasting on the Mesoscale
- Advanced ensemble-forecasting technique through
a first-time calculation of approximate analysis-error
covariance singular vectors given the ensemble from
the EnKF 12
- Examined singular vectors in the idealized context
of the quasi-geostrophic Eady model 13
- Produced a simple
scale- and flow-dependent calibration that corrects
deficient spatial variance model errors 14
Verification of Forecasts based on Mesoscale Predictability
- Verified
mesoscale model forecasts based on mesoscale predictability,
allowing easier interpretation of model
errors 15
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Life Cycles of Precipitating Weather Systems
Understanding of how precipitation systems initiate, mature,
and decay is a fundamental problem in atmospheric science.
This understanding
is central to quantifying the intrinsic predictability of these
systems and improving methods to forecast such systems.
Achievements include:
Convection Initiation
- Improved understanding of convection initiation through
numerical simulation of atmospheric bores 16
- Addressed land-surface
variability and dry-line convection through a
multiscale study of convective initiation in a mesoscale model 17
Complex Mesoscale Environments
- Organized and conducted the Bow Echo and Mesoscale
Convective Vortex Experiment (BAMEX) field campaign
to understand convective evolution in complex mesoscale
environments 18
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BAMEX Convective Evolution maps (click
to see larger image and full text) |
- Analyzed STEPS data to help improve
knowledge of the interactions between kinematics, precipitation
production, and electrification in thunderstorms on the High
Plains 19
Orographic Effects
- Increased understanding of orographic control of rainfall
patterns by analyzing warm-season rainfall with spatially
averaged diurnal composites of
precipitation frequency and by researching convection initiation over heated
topography 20
Dynamics of Mesoscale Convection
- Furthered understanding of the long-time-scale dynamics
of mesoscale convective systems by examining systematic
variability of warm-season rainfall
over the continental US
- Explored the global significance of recent warm
season precipitation climatological findings 21
Microphysics
- Developed analysis software for the community to examine
in situ aircraft microphysical particle data
- Implemented
a microphysical scheme into the Clark-Hall small-scale
dynamical
model 22
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Mesoscale Data Assimilation
The primary goal of mesoscale data assimilation research is to
develop and support state-of-the-art data assimilation systems
for application in high-resolution mesoscale models. These data
assimilation systems can be used for a variety of purposes including
the assimilation of data from new observing systems, the optimal
use of observations, and understanding the observational requirements
for accurate precipitation forecasts and the optimal strategies
for obtaining targeted observations.
Achievements include:
Advanced data assimilation systems for community use
- Released the MM5/WRF 3DVAR data assimilation system
(http://www.mmm.ucar.edu/3dvar) and WRF (http://www.wrf-model.org/WG4/wg4_main.html)
to the research communities
- Implemented the MM5/WRF 3DVAR
system operationally in worldwide MM5-based
domains at the US Air Force Weather Agency; developed a real-time mesoscale
ensemble forecasting system (http://rain.mmm.ucar.edu/mm5)
- Continued development
of an EnKF system for regional mesoscale data assimilation
based on WRF23
- Modified the MM5/WRF 3DVAR system to include
vertical velocity, cloud water, and rainwater increments
24
- Simulated Indian monsoon weather systems and investigated
the impacts of data assimilation methods and physical parameterizations
25
- Assimilated
surface observations with an EnKF data assimilation system
26
- Developed
software, currently employed by investigations worldwide,
to reduce the dimensions of datasets
- Developed a numerical technique to
correct the time-lag and calibration errors in the Vaisala
radiosonde humidity measurements
New observing systems
- Developed a systematic framework to analyze optimal
observing systems 27
- Applied EnKF to the analysis and prediction
of convective scale motions using simulated observations
in a cloud model 28
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High-Resolution Weather Research
and Forecast (WRF) Model Development
The overall goal of the WRF Model project is to develop a next
generation weather forecast model and assimilation system that
will advance both the understanding and prediction of mesoscale
weather and will accelerate the transfer of research advances into
operations. The model is being developed in collaboration with
NCEP, FSL, AFWA, NRL, OU/CAPS, and the FAA, and we expect that
this collaboration will lead to closer ties between the research
and operational forecasting communities.
Achievements include:
WRF Model Development and Experimental Real-time Forecasting
- Documented realistic spectral resolution of WRF model
forecasts, consistent with low dissipation in the model
numerics
- Incorporated the nonhydrostatic NMM dynamic core
as a second option
along with the Eulerian mass-coordinate core and ported the NMM core and
suite of NMM physics to the WRF Advanced Software Architecture 29
- Implemented one-way
and two-way grid nesting schemes 30
- Parallelized the mass-core
initialization for real-data cases for distributed memory
architectures
- Ported the WRF to seven of the top 30
fastest high-performance computers in the world
- Developed
a flexible, re-usable software infrastructure for high-resolution
regional coupling of WRF with ocean and ecosystem models for prediction
of hurricane intensification, ecosystem and environmental modeling, simulation
of air quality
and chemical dispersion, and other problems of vital concern 31
- Collaborated
with Chinese CAMS to guide their use of major WRF components
- Performed
convective-resolving real-time forecasts using the WRF
model in support of the BAMEX field operations and
initiated real-time forecasts for Hurricane Isabel
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| WRF Model BAMEX animation (click to
see movie and text) |
WRF Model Isabel animation (click
to see movie and text |
Community Contributions
- Released WRF beta-version 1.3 in March 2003 and updated
version 1.3.1 in June 2003 to the research communities
- Organized
the Fourth WRF Users Workshop, a 2½-day WRF tutorial,
32 the 13th Annual MM5 Users Workshop, and two MM5 tutorials
- Advanced the Antarctic
Mesoscale Prediction System (AMPS) and improved the radiation,
surface physics, and sea-ice fraction representation
for polar regions 33 http://www.mmm.ucar.edu/highlights/03feb_powers/powers0303.html
WRF Facilities
- Established a Developmental Testbed Center (DTC) facility
at NCAR that will accelerate the direct transfer of new
research results from WRF into the
NWS and other operation forecasting processes
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Deep Convective Cloud Systems
The goal of this program is to understand convective cloud systems
on time scales up to intraseasonal, how they influence large scales,
and how they can be parameterized. The accomplishments below are
part of the NCAR Clouds in Climate Program (CCP), which is a concerted
effort to bring together process studies and research on parameterization
of deep convection relevant to climate modeling and numerical weather
predication.
Achievements include:
MJO Dynamics
- Simulated the large-scale organization of tropical convection
on intraseasonal time scales, identifying the importance
of free-tropospheric moisture
- Formulated a theory for MJO-like
systems involving an analytic parameterization
of organized convection and verified the theory against super-parameterization
results
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Theory for MJO-like systems (click
to see larger image and full text) |
Super-Parameterization
- Implemented a super-parameterization in the CCSM with
focus on the tropical western Pacific and organized convection
and extended the super-parameterization
framework 34
U.S. Warm Season Precipitation Sequences
- Simulated traveling organized precipitating systems
observed during the North American warm season, finding
encouraging agreement with continental-scale
radar measurements
- Formulated a dynamical mechanism for traveling heavy
precipitation
Microscale Physics
- Examined decaying moist turbulence 35 and the effects
of turbulence on cloud-droplet
Collisions 36
- Improved the parameterization of microphysics and the
planetary boundary layer 37
- Quantified interactions among
cloud-microphysical processes, radiative transfer, and
shallow convection 38
- Conducted microphysical measurements
in the Convection and Moisture Experiment (CAMEX-4) and
Hurricane Humberto 39
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Boundary Layer
The division made advancements in understanding both cloudy and
clear boundary layers. Through coordination with the GEWEX Cloud
System Study (GCSS) program, the division made strides towards
understanding the physical processes of the climatologically important
marine stratocumulus clouds and representing their effects in climate
models. Small changes in fractional cloud cover or microphysical
properties can drastically alter the amount of solar radiation
input to the ocean surface. Hence, an accurate representation of
this cloud regime in a coupled model is required to simulate accurately
the energy budget of the Earth’s surface. Energy exchanges
in the nocturnal PBL and turbulence structure in the clear-air
PBL are both important topics for improving the performance of
numerical models that predict PBL flows.
Achievements include:
Marine Stratocumulus Regime
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- Both radar and in situ measurements from
the NCAR C-130 aircraft in DYCOM-II show that drizzle
in marine stratocumulus clouds is associated with mesoscale
cellular organization of the clouds. This was confirmed
by satellite images.
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| Radar and in situ measurements from the NCAR C-130
aircraft in DYCOM-II (click to see larger image and full
text) |
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- Estimated entrainment rates for the marine stratocumulus
regime off the California coast with unprecedented accuracy
from aircraft tracer flux
measurements.
- Explored a novel idea for the amelioration of global
warming by the advertent and controlled enhancement of
the albedo
and longevity of low-level
maritime clouds 40
- Analyzed and modeled comparisons of the DYCOMS-II data
41 and case studies to demonstrate that LES can reproduce
the turbulence and cloud field 42
Clear-air Boundary Layers
- Investigated the nocturnal boundary layer 43 and performed
two-dimensional modeling of boundary-layer convection 44
- Performed
implicit turbulence modeling 45 and developed a methodology
for quantifying numerical dissipation as an implicit turbulence model 46
- Performed
direct numerical simulation of oceanic boundary-layer current
separation 47
- Applied a Lagrangian particle model to study turbulent
dispersion of scalar 48
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Surface-Atmosphere Interactions
The goal of this project is to understand the interactions between
the atmospheric boundary layer and the underlying surface and to
improve the parameterization of air-surface interactions in synoptic-,
meso-, and large-eddy-simulation models. Surface heterogeneity
plays an important role in the exchange of carbon dioxide between
the atmosphere and terrestrial biosphere, a role that is very important
from a global climate perspective.
Achievements include:
Land-Surface Couplings: Measurements and Modeling
- Researchers coupled atmospheric LES and Land-Surface
models in order to examine the response of the PBL to large-scale
soil moisture heterogeneity.
The scales considered ranged from 1-18 times the PBL height (5 to 30 kilometers).
Land-surface variability was found to induce organized motions in the atmosphere
that scale with the heterogeneity. They also found that time-averaged measurements
at a point can incorrectly estimate the total vertical moisture flux by
up to 60%. The error varies with the height and location
of the measurement station
in the region of heterogeneity.
- Researchers coupled atmospheric LES and Land-Surface
models in order to examine the response of the PBL
to large-scale soil moisture heterogeneity. The scales
considered ranged from 1-18 times the PBL height
(5 to 30 kilometers). Land-surface variability was
found to induce organized motions in the atmosphere
that scale with the heterogeneity. They also found
that time-averaged measurements at a point can incorrectly
estimate the total vertical moisture flux by up to
60%. The error varies with the height and location
of the measurement station in the region of heterogeneity.
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LES and Land-Surface models have been
coupled to examine PBL (click to see larger image and
full text) |
Ocean-Surface Couplings: Measurements and Modeling
- Developed a new method to analyze measurements of oceanic
waves and atmospheric turbulence gathered from a moving
platform 72 Participated in the CBLAST-low field campaign
to study air-sea interaction under weak wind conditions
55 http://www.whoi.edu/science/AOPE/dept/CBLAST/lowwind.html
- Developed
a new LES code with the capability of imposing a moving
sinusoidal wave at its lower boundary 56 for modeling atmospheric
marine boundary layers
- Implemented a stochastic model of
breaking waves in turbulence-resolving simulations of
ocean boundary layers 57 driven by high winds
Parameterizations and LES
- Improved a subgrid-scale (SGS) model for LES of plant-canopy
environments 58
· Analyzed the subfilter scale motions obtained from the Horizontal Array
Turbulence Study (HATS) 59
Modeling with Topographic Influences
- Developed a variant of the nonhydrostatic model EULAG
for numerical simulation of sand dune evolution in severe
winds 60
- Investigated physical mechanisms governing the daytime
evolution of
up-valley winds in mountain valleys 61
- Simulated two-dimensional moist neutral
flow over a ridge 62
- Investigated the basic fluid mechanics
of orographic wake formation related to upstream blocking
63
- Developed
an adaptive grid-refinement approach, embedded in the framework
of a nonhydrostatic anelastic model for simulating geophysical flows using
NFT numerical methods 64
- Refined the iterative upwind scheme MPDATA in a Finite
Volume framework 65
- Applied mathematical/numerical techniques
to model the quasi-biennial oscillation 66
- Explored explosive crown fire dynamics with infrared
imagery 71 and
applied NCAR’s coupled atmosphere-fire model to the
Big Elk Fire near Lyons, CO 72
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Chemistry, Aerosols, and Dynamics
Interactions Research
The main goal is to develop an understanding of the interactions
between atmospheric dynamics, aerosols, and chemistry at the meso-
and cloud-scales, particularly with respect to the coupling between
transport, cloud physics, and chemistry. This is important for
improving and developing parameterizations for large-scale models
and for supporting the goals of the Global Tropospheric Chemistry
Program (GTCP) and climate research.
Achievements include:
- Used MM5 to drive a tracer model for insect migration
67 and developed a real-time insect migration forecast
system
- Used
a one-dimensional global model to predict mean vertical
structure
and fluctuations in trace gas concentrations as a function of species
lifetime in the atmosphere 68
- Determined that turbulence-induced segregation of
chemical species, using LES coupled with gas-phase chemistry,
can be reduced by other,
simultaneous chemical reactions producing the species of interest 69
- Simulated
the chemistry and microphysics of fair weather cumulus
to determine the role clouds play on ozone photochemistry
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| Simulated chemistry
and microphysics to determine role of clouds in ozone
photochemistry (click to see larger image and full text) |
- Performed detailed cloud physics and
chemistry simulations to reveal the sensitivity of aqueous chemistry
to the cloud microphysics parameterization.
Improvements to the cloud parcel model include the representation of
multicomponent aerosols which affect cloud drop activation 70
- Developed plans
for using WRF-chem to investigate tracer transport in convection
at the cloud scale and to coordinate this work with global
scale studies of convective tracer transport
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