Executive
Summary
RAP's
research and development emphases are: in-flight icing; snowfall and
freezing precipitation; convective weather forecasting; ceiling
and visibility; atmospheric turbulence; numerical weather prediction;
land-surface modeling; remote sensing of precipitation; precipitation
enhancement; hybrid automated forecast systems, statistics application
and forecast verification. Significant technology transfer activities
include development of an advanced aviation weather system for
Taiwan, a real-time mesoscale modeling system for the U.S. Army,
an icing diagnosis system, and a road weather maintenance support
system. In addition, RAP is leading strategic initiatives in
the areas of Wildland Fire and Water Cycle Across Scales and has significant
involvement in the Weather and Climate Extremes Assessment and
the Geographic Information Systems initiative.
Photo © Paul Bowen
Trailing vortices and downwash phenomenon of an aircraft in
flight.
A. In-flight
Icing
In-flight icing research has continued at RAP for more than twelve
years and provides both interesting and challenging studies in cloud
physics, remote sensing, and mesoscale meteorology. The goal of this
research is to develop more accurate and timely diagnoses and forecasts
of conditions leading to ice accretion on aircraft during flight.
A major milestone was reached this year with the operational acceptance,
by the FAA and NWS, of the Current Icing Product, or CIP. The algorithm
combines sensor data with model output, and has shown superior skill
in diagnosing the location of in-flight icing conditions. A forecast
version is still in the experimental stage. An Alaska version and
an icing severity diagnosis are under development. Marcia Politovich
leads this effort. Collaboration with the NOAA/ETL and FSL, the U.S.
Army Cold Regions Research and Engineering Laboratory, NASA Glenn
Research Center, Colorado State University, University of Alaska Fairbanks
and Radiometrics, Inc. have helped further this research.
Achievements include:
1. Acceptance of the Current Icing Product (CIP) for
operational use by the FAA and NWS. The algorithm combines sensor
data with model output, and has shown superior skill in diagnosing
the location of in-flight icing conditions.
2. Acceptance of the Forecast Icing Product (FIP) for experimental
use.
3. Development of an Alaska version of CIP and FIP.
4. Earning the 2001 NASA "Turning Goals into Reality" award
as part of the Aircraft Icing Project Team (awarded November 2001).
5. Inclusion of RAP and MMM-developed microphysics parameterization
in the upgraded Rapid Update Cycle model run operationally at the
National Center for Environmental Prediction.
B. Snowfall
and Freezing Precipitation
RAP has a successful history of involvement with airport
and aircraft operations dealing with the impacts of snow and freezing
precipitation. The operation of aircraft during snow and freezing
rain or freezing drizzle conditions is a significant safety issue
due to the rapid loss of lift and increase in drag produced by ice
accumulation on aircraft. Snow and freezing rain accumulations on
taxiways and runways also impact the safety and efficiency of ground
operations. With funding from the FAA's Aviation Weather Research
Program and the FAA Technical Center, RAP continues to work, under
the leadership of Roy Rasmussen, to improve nowcasts and forecasts
of snowfall and freezing precipitation in collaboration with DRI,
Texas A&M, Rutgers, Univ. of Quebec at Montreal, Univ. of Pecs,
Hungary, and MMM.
Achievements include:
1. Demonstration that improved forecasts of snow and
freezing precipitation are achievable if data assimilation techniques
take into account the three-dimensional fields of precipitation mixing
ratio (through the radar reflectivity), Doppler radar winds, temperature,
and water vapor mixing ratio.
2. Improvement of the hotplate snowgauge algorithm. The algorithm
now meets the NWS criteria for precipitation measurement accuracy
and is ready for commercialization.
3. Establishment of a correlation between outdoor natural snow testing
of deicing fluids with indoor snow testing with the NCAR snowmachine,
paving the way for adoption of the NCAR snow machine for testing aircraft
de/anti-icing fluids.
4. Documentation of the current forecast skill of the RUC operation
model. This information will be used as a baseline from which future
improvements to the snow and freezing precipitation capability of
RUC can be evaluated.
C.
Convective Weather Forecasting
Predicting the initiation, location, and dissipation
of new convection 30 min to 2 hour in advance is one of the challenges
of convective weather forecasting. RAP conducts research and development
efforts aimed at improving thunderstorm nowcasting systems on both
the local (Convective Storm Auto-Nowcast System [ANC]) and national-scales
(National Convective Weather Forecast [NCWF]). Cindy Mueller leads
this work. Collaboration with MIT/Lincoln Lab, NOAA/NSSL, McGill,
and MMM.
Achievements include:
1. Improved diagnosis of gust fronts with Variational
Doppler Radar Analysis System (VDRAS) during a
regionalized version of NCWF (RCWF) when the evaporative cooling
parameterization was included.
2. Obtaining an excellent dataset during the IHOP field program with
which to conduct research on convective triggering relevant to both
FAA and NCAR Water Cycle initiative scientific goals.
3. Successful use of the RUC model analyses and forecasts of stability
(CAPE and CIN) to improve forecasts of deep convection.
4. Continued improvement of techniques to use satellite data to improve
0-2 hour forecasts of convection.
D. Atmospheric
Turbulence
RAP is involved in a number of research and development
programs aimed at minimizing the number and severity of aircraft encounters
with turbulence. Under the leadership of Bob Sharman and Larry Cornman,
work continues to improve and implement methods for better diagnosis
of turbulence, using in-situ instruments or remote sensing devices
such as radar and lidar, and to develop, implement and verify automated
forecasts of upper level turbulence. RAP also continues to develop
a Juneau Airport Wind System for the FAA; this effort is led by Bob
Barron. Collaboration with NOAA/FSL, Univ. of Alaska, Fairbanks and
Anchorage, UCLA, Marquette, Univ. of Wyoming, Univ. of Oklahoma, Univ.
of Colorado, MMM, ATD, and UOP/GST.
Achievements include:
1. Improving the in-situ turbulence detection algorithm using data
from a NASA B757-200 during flights in a recent field program.
2. Enhancement and testing of the turbulence detection algorithm based
on forward-looking airborne Doppler radars using data from NASA B-757
research aircraft. The results of this testing showed that the improved
algorithm detected turbulence 30 s in advance 80% of the time, even
in regions returning a weak radar signal.
3. Development of improved quality control and turbulence detection
algorithms for the WSR-88D operational ground-based radars based on
data from the STEPS field program.
4. Improved LIDAR detection of turbulence through idealized wind field
simulations and LIDAR detection simulations.
5. Addition of a mountain wave turbulence algorithm to the Integrated
Turbulence Forecasting Algorithm (ITFA).
6. Development of a global ITFA product using output from NOAA's AVN
model.
7. Discovery through numerical simulations and analysis of NASA aircraft
data that high-intensity, short-lived turbulence events are often
anisotropic, with more energy in the vertical wind components than
the horizontal.
8. Identification of "four" hot spots for turbulence generation
in the Juneau, Alaska region based on aircraft and radar data.
E. Ceiling
and Visibility
Adverse ceiling and visibility (C&V) conditions
are a contributing factor in over 35% of all weather-related aviation
accidents in the U.S. and are a major cause of flight delays nationwide.
RAP research, funded by the FAA and NRL, directly addresses hazardous
C&V conditions both on the national scale and in the airport terminal
area. Paul Herzegh and Wes Wilson lead the C&V program at NCAR.
Collaboration with NRL, NOAA/FSL, MIT/Lincoln Laboratory, Brookhaven
National Laboratory, Rutgers, Univ. of Quebec at Montreal.
Achievements include:
1. Addition of four times-daily Eta model forecasts to the National
Ceiling and Visibility product.
2. Determination that short-term visibility nowcasts during snow conditions
are possible using a real-time correlation of visibility and radar
reflectivity and the tracking and advection of snow radar reflectivity.
3. Establishment of two heavily instrumented field sites at Rutgers
University in New Jersey and Brookhaven National Laboratory on Long
Island for the Northeast Corridor Ceiling and Visibility study. This
data will be used to develop improved algorithms to diagnose and detect
ceiling and visibility in the Northeast United States.
4. Preliminary study of fog events in the New York City airport region.
F. Oceanic
Weather
In 2001, RAP began a new program of applied research
and development that addresses the international need for better nowcasts
and forecasts of flight conditions and weather-related aviation hazards
in data-sparse oceanic regions. The program, sponsored by the FAA
and led by Tenny Lindholm, works to develop improved wind field information
and the diagnosis and nowcasting of aviation-critical phenomena such
as convection, flight-level turbulence, volcanic ash, and in-flight
airframe icing. Collaboration with Univ. of Alaska, Fairbanks, Univ.
of Wisconsin, NRL, MIT/Lincoln Lab.
Achievements include:
1. Improved capability to determine cloud top using IR satellite data
and AVN model sounding data.
2. Development of a prototype expert system to diagnose convection
over the ocean using the Naval Research Laboratory's satellite-based
cloud classification scheme and global lightning data.
3. Identification of strategies that can improve the current infrastructure
for detecting, forecasting, and communicating volcanic ash dispersion
along flight routes.
4. Development of a climatology of aircraft turbulence encounters
over oceanic flight routes.
5. Development of a real-time global turbulence detection product
using output from the AVN global model based on a similar product
developed over the CONUS using RUC model output. PIREP turbulence
information is used to help determine the diagnostic.
G. Numerical
Weather Prediction
Numerical weather prediction at RAP is focused on developing,
testing, and implementing operational forecasting systems. This entails
better understanding of local dynamical processes through the use
of special data, development of improved representations of physical-processes
in the models, and objectively verifying the skill of the models at
predicting local meteorological processes. Tom Warner directs modeling
activities within the division in collaboration with Penn State, Univ.
of Colorado, Univ. of Utah, UCLA, CSU, and MMM.
Achievements include:
1. Deployment of the ATEC modeling system at the Army's Cold Regions
Test Center in Greely, Alaska with horizontal resolution down to 1.1
km.
2. Deployment and operation of the ATEC modeling system for the Salt
Lake City Winter Olympics (horizontal resolution down to 1.1 km) to
provide mesoscale wind fields for emergency response organizations
tasked with assessing the possible impact of the release of airborne
hazardous materials.
3. Development of improved model verification statistics for high-resolution
mesoscale model simulations that take into account errors in location
and timing more appropriately than current statistical methods.
4. Deployment of the ATEC modeling system for a missile test at the
Pacific Missile Range Facility (PMRF) in Kauai, Hawaii.
5. Deployment of the ATEC modeling system with a transport and dispersion
module in support of ground operations during the Afghanistan war.
6. Modeling of near surface flow over the Southern California Bite
in order to assess the impact of wind stress on the oceanic coastal
circulation.
7. High resolution modeling support for the Hayman and Missionary
Ridge wildfires.
H. Water
Resources
Water resource activities in 2002 were focused in three
primary areas: 1) surface hydrology for urban flash flood analysis;
2) hydrologic and water resource assessment of rainfall enhancement
benefits in the United Arab Emirates; and 3) land-atmosphere interactions
associated with the Cooperative Atmospheric Surface Exchange Study
(CASES) and the International H2O (IHOP) experiment, and the use of
Geographical Information Systems in their analysis. This last research
area closely relates to the "Land-Surface/Atmospheric Interactions"
section of this report, with the concurrent goal of improving knowledge
of land-surface interactions for regional weather, climate, and hydrology.
David Yates and Tom Warner provide leadership for this effort. Collaboration
with USGS, Univ. of Colorado, and MMM.
Achievements include:
1. Demonstration that radar-based estimates of precipitation combined
with surface gauge data can improve the predicted peak and total storm
discharge estimates of runoff. The value of a 30-minute nowcast of
precipitation from the Autonowcaster was also demonstrated.
2. Establishment of the relationship between rainfall and wadi flows,
rainfall and reservoir levels, rainfall and ground water levels, and
the relationship among these.
3. Use of a water resource decision support tool, the Water Evaluation
and Planning Model (WEAP), to perform comparative analysis of demand
and supply at various spatial and temporal scales for the UAE.
4. Determination that landscape variations such as ridges and ravines
(in addition to vegetative cover, soil moisture and soil type) play
an important role in determining fluxes of heat, moisture and winds.
I. Land-Surface/Atmospheric
Interactions and Their Modeling
Through both theoretical and observational studies,
RAP scientists work to understand the complex interactions (including
biophysical, hydrological, and bio-geochemical interactions) between
the land-surface and the atmosphere at micro- and meso-scales, and
to improve land-surface models. The ultimate goal is to integrate
such knowledge into numerical mesoscale weather prediction and regional
climate models in order to improve prediction of the impacts of land-surface
processes on regional weather, climate, and hydrology. To achieve
these objectives, a number of research and application studies were
conducted.
Achievements include:
1. Deployment of 10 surface flux stations as part of the IHOP field
program (supported by the NCAR Water Cycle initiative).
2. Development of a unified land surface modeling system for eventual
deployment in WRF. This development is a collaborative effort between
NCAR, NCEP and the Air Force Weather Agency (AFWA).
J. Remote
Sensing of Precipitation
In efforts funded by the FAA, USWRP and the Water Cycle
initiative, RAP has been actively involved in the development of techniques
for monitoring precipitation with polarimetric radar measurements.
Ed Brandes directs this work. Collaboration with NOAA/NSSL, CSU, and
ATD.
Achievements include:
1. Improvement of multi-parameter radar estimates of precipitation
using a relationship between the shape of a gamma raindrop size distribution
and the slope of the distribution.
2. Demonstration of the feasibility of estimating droplet size and
liquid water content using dual wavelength (Ka and X band) radar measurements.
This information is critical to in-flight icing applications, as both
mean drop size and liquid water content are key quantities determining
ice accreted on a wing.
3. Development of a Cross-Correlation Ratio (CCR) method to estimate
transverse wind components from spaced antenna radar systems.
K. Precipitation
Physics
In many regions of the world, particularly in arid or
semi-arid lands, traditional sources and supplies of ground water,
rivers and reservoirs are either inadequate or under threat from ever
increasing water demands. This has prompted atmospheric scientists
to explore the possibility of augmenting water supplies by means of
cloud seeding. During FY2002, RAP scientists were involved with a
program in the United Arab Emirates to evaluate the potential of hygroscopic
cloud seeding there. Studies were also conducted on hygroscopic flare
characteristics. Roelof Bruintjes directs this effort. Collaboration
with Arizona State University, University of Witswatersrand, South
Dakota School of Mines, Al-Ain University, and MMM.
Achievements include:
1. Determination that seeding opportunities in the UAE during the
winter season were limited due to a lack of clouds, while summer seeding
opportunities over the Oman Mountains were more promising due to the
frequent formation of storms in that region.
2. Discovery that local emissions of SO2 gas were high, and resulted
in significantly high concentrations of sulfate particles due to gas
to particle conversion by oxidation. These enhanced sulfate concentrations
were hypothesized to affect the CCN concentration and subsequent cloud
and precipitation formation. The coating of mineral dust particles
by sulfates was found to be not as important as previously hypothesized.
3. Establishment of a hygroscopic flare testing facility.
L.
Hybrid Automated Forecast Systems
RAP continues to develop hybrid automated forecast systems,
blending real-time observations, numerical weather prediction model
output, climatological, and statistical data to improve forecast results.
This year, the use of the hybrid automated forecast system approach
was expanded with the introduction of ensemble methods. Key areas
of application include the Winter Road Maintenance Decision Support
System (MDSS), the U.S. Army Meteorological Measuring System, the
Dynamic, Integrated Weather Forecast system (DICAST), and rail weather.
Bill Mahoney, Rich Wagoner and Bill Myers play key leadership roles
in these programs. Collaboration with NOAA/ETL, FSL, NSSL; CRREL,
MIT/Lincoln Lab, and ESIG.
Achievements include:
1. Development of a functional prototype MDSS using road segments
and winter storm cases from Minnesota.
2. Enhancement of the DICAST system by the introduction of ensemble
techniques, forward error correction, and quality control techniques.
3. Hosting a rail weather workshop with participants from the Federal
Railroad Administration, the Association of American Railroads, Federal
Highway Administration, several railroad companies, private sector
meteorological companies, and national laboratories.
M. Statistics
Applications and Forecast Verification
The RAP Verification Group continues to provide independent
verification of improved aviation weather forecasting systems developed
both at NCAR and at external laboratories. A major study in 2002 involved
evaluation of the Integrated Turbulence Forecasting Algorithm, which
is being considered for operational status. Barbara Brown directs
the verification program at NCAR. Collaboration with NOAA/FSL, MMM,
and ESIG.
Achievements include:
1. Hosting a verification workshop entitled "Making Verification
More Meaningful".
2. Initiating a project to develop an object-based approach to verify
precipitation and convective weather forecasts.
3. Development of a method to detect inhomogeneities in precipitation
observations due to instrument drift, alterations in the method of
measurement or reporting, modification of the stations surrounding,
etc
N. Technology
Transfer Activities
The application of scientific research and development
to societal problems is at the heart of the RAP mission. Decision-makers
in a variety of agencies and weather-sensitive industries need improved
weather information and tools, and RAP works to transfer new capabilities
into their hands. Transfer of technologies to the aviation community
continues to be a major emphasis with improved capability for the
automated forecasting of inflight aircraft icing, thunderstorms, snowfall
affecting airport ground operations, turbulence, ceiling and visibility,
and oceanic weather occurring each year. Other significant technology
transfers have occurred within the context of RAP's DoD, surface transportation
and public weather programs. Bill Mahoney, Scott Swerdlin, Marcia
Politovich, and Bill Myers have directed these technology transfer
efforts.
Achievements include:
1. Completion of the Advanced Operational Aviation Weather System
(AOAWS) program, a six-year long development and technology transfer
program between the U.S. Government and Taiwan. In FY02 the AOAWS
system was successfully tested and delivered to Taiwan's Civil Aeronautics
Administration. The system is now operational and being used by the
aviation community in Taiwan and by airlines that fly into Taiwan.
*The
AOAWS won NCAR's Scientific and Technical Outstanding Accomplishment
Award in 2002, which recognizes efforts leading to substantial improvements
in scientific and/or technical capabilities, including advances in
hardware or software engineering, computer science, and applied science.
The project and team was recognized for the "efforts of a large,
interdivisional team that has worked together for the past six years".
A more detailed description of this award can be found on the
AOAWS page in this ASR.
2. Deployment of two new Four-Dimensional Weather Systems (4DWX) for
the U.S. Army Test and Evaluation Command (ATEC). The two new systems
supported the war in Afghanistan and counter-terrorism efforts at
the 2002 Winter Olympics in Salt Lake City.
3. Achievement of "operational" status for the Current Icing
Potential (CIP) product. In FY02 the Aviation Weather Center approved
the CIP for official use by the aviation community. This marks the
final step in the technology transfer process for aviation products.
4. Public release of the Winter Road Maintenance Decision Support
System (MDSS) functional prototype.
O. Contributions
to NCAR Initiatives
RAP has made significant contributions to four NCAR
initiatives: Water Cycle Across Scales, Wildland Fire Collaboratory,
Weather and Climate Impact Assessment, and Geographic Information
Systems.
1. Water Cycle Across Scales
RAP continues to lead this initiative, with Roy Rasmussen directing
the steering committee. Participating divisions include ATD, MMM,
and CGD. Key activities by RAP staff in FY02 included participation
in the IHOP field program, initial data analysis, and deployment of
surface flux measurement instruments; participation in the IMPROVE
II field program off the coast of Oregon; preliminary research on
predictability using IHOP datasets; improved precipitation estimation
datasets using IHOP data; and application of the USGS Precipitation
Runoff Modeling System (PRMS) to runoff watersheds in the Denver area.
2. Wildland Fire
Rich Wagoner leads this initiative; participating divisions include
ESIG, MMM, ATD, ACD, CGD and ASP. The RAP effort continues to focus
on building the Wildland Fire Collaboratory, an international forum
for exchanging information relative to wildland fire research and
development activities and for accelerating the transfer of knowledge
and technology from the research community to the operational community.
Extensive outreach to the wildfire community has resulted in the successful
recruitment of a diverse group of federal laboratories and agencies,
universities, and state forestry departments. Over the past year this
group has worked to identify and prioritize the fire science and social
science tasks that are needed to ultimately design and build decision
support systems to implement the National Fire Plan.
3. Weather and Climate
RAP has partnered with ESIG to conduct research into climate and weather
extremes. In FY02 RAP scientists began to develop an "extremes
toolkit" comprised of software and a Web-based tutorial to better
communicate meteorological extremes to the broader atmospheric community.
The potential of applying extreme value theory to forecasting icing
severity is also being assessed. During FY02, RAP and ESIG scientists
examined the problem, developed an analysis approach, and identified
datasets to be analyzed.
4. Geographic Information Systems
While still a small effort, progress has nevertheless
been made by ESIG and RAP in developing a GIS Program at NCAR. Thus
far the bulk of the work funded by the NCAR GIS strategic initiative
has focused on education, promoting the use of GIS as an analysis
and infrastructure tool and beginning to examine broader data management
and geoinformation issues. In parallel, research in GIS technology
has also begun. With NSF funding for a GIS Demonstration Project last
summer and contingency funding from the RAP Director, RAP is working
to compare the applicability of GIS strategies to data interoperability
issues. Using data collected during the IHOP field program, an open
source strategy, based on specification standards set by the Open
GIS Consortium, is being compared to a commercial approach based on
products developed by ESRI, the leading vendor of GIS software in
the U.S. Partnerships with ESRI, IBM, and the OCG, as well as collaborations
with GIS experts at universities and national laboratories, are also
being forged.
[TOP]