The Next Generation Air Transportation System (NextGen) is a national priority designed to meet the air transportation needs of the US in the 21st century—in particular, a significant growth in demand for air traffic services, possibly on the order of three times today's demand levels.  Since weather conditions can seriously restrict aircraft operations and levels of service available to system users, the manner by which weather is observed, forecast, disseminated, and used in decision-making is of critical importance. 

Web display of CoSPA analysis and forecast products, including select routes.

For more than two decades the Federal Aviation Administration (FAA) has funded research and development efforts aimed at improving short-term forecasting of storm hazards affecting aviation.  This effort brings together researchers from NCAR's Research Applications Laboratory, MIT Lincoln Laboratory, and NOAA ESRL's Global Systems Division to create 0-8 hour forecasts of precipitation phase and intensity and echo top heights.  The forecasts are generated utilizing an advanced blending technique that merges heuristic-based extrapolation forecasts produced by MIT Lincoln Laboratory with output from the High-Resolution Rapid Refresh (HRRR) model running at NCEP.  The forecast system is being developed to satisfy the current needs of Air Traffic Management (ATM), as well as the future demands of NextGen, in which much of the strategic air traffic decision-making will be made utilizing automated decision support tools based on gridded probabilistic forecasts. 

Highlights

Since 2010 CoSPA encompasses the entire continental US as well as parts of the Gulf of Mexico, Eastern Atlantic and Southern Canada.  A major milestone was reached during the summer 2010 when CoSPA was fielded at a number of FAA and airline facilities, and used in the daily operational aviation planning process for a first time.  The extensive operational evaluation conducted during the summer 2010 demonstrated substantial benefits of CoSPA to daily ATM planning.

CoSPA forecasts continue to be made available to aviation planners via a web-based display from April through October (i.e., convective season) and, since fall 2015, also throughout the rest of the year (winter season).  The display allows users to overlay airports and associated arrival and departure fixes, route structures, and sectors on current and forecast weather facilitating the product’s utility. The CoSPA forecast products have been in use as a supplemental product for many years and are currently undergoing technology transfer to the FAA.

The final version of CoSPA will be delivered for installation as part of the FAA’s NextGen Weather Processor (NWP) in August of 2018.

ONGOING RESEARCH

Research and development has continued toward improving the CoSPA forecast system as well as the system architecture.  Major enhancements have recently focused on speeding up the algorithm to allow for a 5 min update rate as well as improving the treatment of storm initiation in the blending algorithm. Improved skill was been achieved by using forecast uncertainty information to inform the blending. Forecast uncertainty is estimated using a time-lagged ensemble of HRRR runs. Areas that have a high probability are given greater weight than areas of lower probability. This new method of blending will be included in the final release which is planned for August 2018.

REAL-TIME DISPLAY

The real-time CoSPA products can be accessed via a password-protected website (https://cospa.wx.ll.mit.edu) hosted by MIT Lincoln Laboratory.

In a typical year, there are 1.2 million weather-related vehicle crashes in the U.S., leading to 445,303 injuries and over 5,897 fatalities. Adverse weather and the associated poor roadway conditions are also responsible for 554 million vehicle-hours of delay per year in the U.S., with associated economic costs reaching into the billions of dollars.

One possible solution for mitigating the adverse impacts of weather on the transportation system is to provide improved road and atmospheric hazard products to road maintenance operators and the traveling public.With funding and support from the U.S. Department of Transportation’s (USDOT) Research and Innovative Technology Administration (RITA) and direction from the Federal Highway Administration’s (FHWA) Road Weather Management Program, the National Center for Atmospheric Research (NCAR) is conducting research to develop the Pikalert® System that incorporates vehicle-based measurements of the road and surrounding atmosphere with other, more traditional weather data sources, and creates road and atmospheric hazard products for a variety of users.

Cloud-seeding parameterization in WRF

The Integrated WEAP and LEAP tools, showing the linking window (center), where common modeling areas, scenarios, periods of analysis, and timesteps are matched. 

In addition to conducting research, NCAR scientists and engineers develop tools and technologies to improve forecasts and inform planning and management decisions.  One of the most powerful decision support technologies NCAR brings to water resource planning and management is the Water Evaluation and Planning (WEAP) model, developed in collaboration with the Stockholm Environment Institute (SEI).  WEAP is a sophisticated, yet user-friendly, tool that couples physical hydrology with relevant water management parameters, set by the user, to create scenarios to explore potential consequences of climate change on water management decisions. WEAP is currently used by several thousand water resource managers in the U.S. and in 170 countries around the world.  Use by utility managers in California, Colorado and Florida has demonstrated the model’s ability to capture regional differences in an area’s dominant hydrologic processes.  The model has also been proven effective in describing a variety of disparate water-management problems, including costs of capital investment, water law, state and local regulations, and ecosystem valuation, to more fully encompass the many non-hydrological variables managers must consider.

Policy and decision makers, particularly in the Western U.S., have long understood the interconnections between water and energy production and use.  Water is needed throughout the energy production system for fuel extraction and processing, power plant cooling, hydroelectric production, etc., and energy is essential for pumping, treating and distributing water.  Efforts to address climate change have heightened awareness of these linkeages—the “water-energy nexus”—and of the need to integrate water and energy planning and management.  Attention is increasingly focused on water scarcity as conflicts emerge and are likely to escalate over competing water demands for energy production, municipal use, agricultural irrigation, and ecosystem protection.  At the same time, energy demand from the water sector—especially for irrigation but also for desalination, water transfers, and water and sewage treatment—has emerged as a serious concern.  

While recognition of water-energy nexus issues has grown, tools that can capture the complexity of the relationships between the resources have only recently been developed.  Scientists from SEI and NCAR have taken the WEAP model, described above, and coupled it with another model, the Long-range Energy Alternatives Planning (LEAP) system, to create a powerful new integrated planning and decision making tool.  WEAP and LEAP can now exchange key model parameters and results and represent evolving conditions in both water and energy systems.  

Using WEAP and LEAP together, planners can now explore how individual water or energy management choices ripple through both systems, understanding tradeoffs that might not be apparent when looking at either system alone. They can then evaluate outcomes against their policy goals and priorities, assess costs and benefits, and tweak decision parameters or make other choices to produce more desirable outcomes.

Thunderstorms and especially lightning pose a safety risk to people outdoors whether they are working or enjoying themselves with recreational activities.  It is imperative to bring people inside to safety whenever thunderstorms and lightning are nearby.

NCAR has been developing algorithms to better diagnose lightning threats and prediction of such threats into the near future enabling more consistent and proactive decisions for bringing people inside to safety.  The BoltAlert^® system processes radar, temperature, and lightning data to derive statistically calibrated lightning probability and lightning safety guidance for specifiable locations.

ONGOING RESEARCH

BoltAlert® lightning potential (high risk in magenta) and actual strikes.

NCAR is working toward a better characterization of the true lightning hazard that is needed as basis for improving the safety of outdoor personnel and minimizing avoidable operational inefficiencies.  Research is underway to combine multiple sources of relevant information (e.g., radar and lightning data from more than one source) for a robust diagnosis of lightning threats.  Moreover, a nowcasting component is developed that enables recognizing lightning threats prior to impact allowing for proactive actions.  Such a capability to alert of impending lightning impacts is of particular interest to airports, sites for handling or testing equipment, fuel, ammunition and missiles, outdoor venues (e.g., baseball parks, swimming pools) and special events (e.g., Olympics), construction and open-air mining sites, utilities (e.g., energy, electricity transmission), recreation (e.g., hiking, camping, boating), transportation, and many others more.

To order BoltAlert® contact: 

info@ral.ucar.edu
303.497.8422

Related Project:
Lightning Impacts on Aviation

Windshear and Turbulence Warning System - Hong Kong

An operational Windshear and Turbulence Warning System (WTWS) was developed for Hong Kong's NewAirport at Chek Lap Kok. The WTWS provides alerts for terrain–and convective–induced windshear and turbulence. The system has been utilized by air traffic controllers and pilots since opening day, 6 July 1998. In addition to providing real–time windshear and turbulence alerts to controllers and pilots, the system provides up to 12–hour forecasts of terminal area turbulence to aviation meteorologists.

Project History

Hong Kong's New Airport at Chek Lap Kok (CLK) is located on partly reclaimed land adjacent to Lantau Island, whose rugged terrain has a maximum elevation of nearly 1,000 meters. Consequently, aircraft operating at the new airport may be affected by significant terrain-induced windshear and turbulence under certain meteorological conditions. In order to enhance safety and operational efficiency at the airport, Weather Information Technologies Inc. (WITI) developed a Windshear and Turbulence Warning System (WTWS) which was installed, tested and has been operational since the airport's opening day, 6 July 1998. Since 1998, the Hong Kong Observatory (HKO) has performed routine evaluations of the system and has made improvements to various sensing systems and wind shear and turbulence detection algorithms.

Hong Kong International Airport

The 44–month project was under the sponsorship of the Hong Kong Observatory. The WTWS development team included WITI, the National Center for Atmospheric Research (NCAR), Hong Kong University of Science and Technology (HKUST), and the University of Wyoming.

Topographical map of the region near Hong Kong's new airport. The highest elevations are above 800 meters.

Components include basic and applied research on wind flow over Hong Kong's terrain, a scientific field study, warning system concept and feasibility studies, system design, development, testing, implementation and training. The WTWS provides real–time hazardous weather information to air traffic controllers and pilots to enhance safety in the terminal area and improve predictions of hazardous weather to support strategic decision making by air traffic managers.

The WTWS is the first system worldwide to provide real–time alerts of terrain–induced turbulence and alerts for both convective and terrain–induced windshear, the WTWS also provides predictions of turbulence caused by terrain and airport surface wind as well as numerical weather prediction guidance. For detection of convective windshear, the WTWS relies partly on the output from a Terminal Doppler Weather Radar (TDWR) at Tai Lam Chung, about 12 kilometers from CLK. The windshear warning system ingests TDWR products including gust front, precipitation intensity, and storm motion, providing an integrated alert system. It generates graphics and text designed for easy interpretation by pilots, controllers, traffic managers and aviation forecasters. It also interfaces with other airport systems, reaching a broader user community including airport authority staff and airline offices.

Prior to the development of the windshear warning system, several studies were conducted in Hong Kong to gain insight into the meteorological conditions near the location of the new airport. These studies included analysis of routine weather observations, special observing programs and meteorological modeling of the differences between the existing Kai Tak Airport and the new airport. Variables that were analyzed included wind direction and speed, temperature, clouds, visibility, rainfall, thunderstorms and fog. Methods used to conduct these studies included investigative flights by light aircraft and water tank and wind tunnel experiments.

The probability of significant turbulence and windshear at Chek Lap Kok during specific meteorological conditions prompted the Hong Kong government to create the WTWS program. It was designed to investigate the detailed wind flow environment near the airport site and based on the scientific results, build and implement an operational windshear and turbulence warning and forecasting system. Following a competition, the project was awarded to Weather Information Technologies Inc. in October 1993.

Note: The WTWS was previously known as the OWWS – the Operational Windshear Warning System.

WTWS Products

The Hong Kong graphical display.

Example of animated replay of recent product history.

The primary WTWS product suite includes detection of terrain-induced turbulence, terrain-induced windshear, convective microburst and windshear, gust fronts, precipitation intensity and storm motion. It also predicts terrain-induced turbulence and airport surface wind and guides mesoscale numerical weather prediction guidance. The graphical and text formats are easily interpreted by pilots, controllers, air traffic managers and aviation forecasters. The alerts use commonly accepted aeronautical navigation terminology.

The WTWS graphic display (above) delivers hazardous weather warning information and other meteorological products. It shows the horizontal profile of various hazardous weather areas, vertical wind profiles near the approach and departure corridors, and textual warning messages. The meteorological situation is displayed in several user-selectable ranges and levels of detail. Critical products and important situation changes are highlighted visually on the display and/or announced by audible signals.

User needs were established over a two-year period culminating in a prototype demonstration in October 1995. As a result of comments by users, the system was designed to provide high performance, distinguish between the phenomena of windshear and turbulence, use existing aeronautical terminology and provide spatial extent of the phenomena as well as 12-hour forecasts of windshear and turbulence at a 30-minute resolution.

Example of an Alphanumeric Alarm Display (AAD) for Hong Kong.

Alerts had to be reserved for significant events and assigned a priority. They also had to be concise but informative and provided within three nautical miles of runways. Products had to support both tactical and strategic decision making and be updated fast enough to cover operations that occur every two minutes.

The alphanumeric alarm display (above) is designed to alert controllers to time-critical weather hazards and to provide textual warnings for communication to pilots. Alerts are given as microburst, windshear or turbulence, with associated intensity and location. For windshear and microburst alerts, intensity is given as headwind "loss" or "gain" in knots; for turbulence, intensity is specified as "moderate" or "severe". The intensity is the maximum expected along the alert corridor and the alert location is where the event is first expected to be encountered. Event locations for windshear alerts are given as one, two or three nautical miles on approach or departure - or on the runway. Event locations for turbulence alerts are identified as departure or approach.

WTWS Status

The Hong Kong Windshear and Turbulence Warning System (WTWS) research and development program, previously known as the Operational Windshear Warning System (OWWS) program, successfully concluded in January 1998. The Hong Kong Government accepted the WTWS system on schedule in July 1997.

Hong Kong International Airport opened its new international airport at Chek Lap Kok (CLK) in July 1998. The WTWS system has been operating since the airport opened. The WTWS is providing windshear and turbulence alerts to pilots arriving or departing the airport when conditions warrant. Input from pilots and controllers is being used to evaluate and tune the system.

Meteorological Reviews

One of the first program tasks was to perform a meteorological review and analysis of historical Hong Kong data. An initial report included a review of scientific theory on airflow around complex terrain, analysis and identification of the conditions which could cause terrain–induced windshear and turbulence near Chek lap Kok, numerical experiments aimed at gaining additional insight into conditions that produce windshear caused by terrain, and an estimate of the timing and location of significant windshear at the new airport.

That review indicated that the primary parameters for determining the nature of the airflow include wind direction and speed, stability, and the presence of critical levels. These parameters were further studied by performing small–scale modeling simulations using the Clark model of a wide range of atmospheric phenomena such as downslope winds, gravity waves and wave amplification, which are often associated with terrain–induced wind flow perturbations. Preliminary results indicated that both mechanical and gravity–wave processes contribute to windshear and turbulence and confirmed that the intensity and location of the turbulence are sensitive, among other things, to wind direction, speed and stability.

A study of test flight results indicated that terrain–induced windshear and turbulence was not related to a single weather phenomenon and should be expected at any time of year. The atmosphere during the turbulence events was variable, although wind speed appeared to have a dominant role in determining intensity. Using 10 years of data, it was found that significant episodes of terrain–induced windshear and turbulence could last from a period of several hours up to a number of days since they were governed by long–term atmospheric motions. Principal phenomena likely to affect aircraft operations at Chek Lap Kok include crosswinds, longitudinal windshear, large wind changes, turbulence, updrafts and downdrafts. It was unclear which condition, if any, would dominate.

Using the knowledge gained from preparing the first meteorological report and from other sources, WITI designed a field experiment to understand fine–scale wind flow in the vicinity of Chek Lap Kok. The basic objectives of the experiment, which was conducted between March 1994 and September 1995, were to quantify the frequency and severity of turbulence and windshear; define more clearly the meteorological conditions under which significant terrain–induced windshear and turbulence occur; validate airflow predictions made by the small–scale model; determine the elements necessary to develop the windshear warning system; and collect verification data.

The major observational platforms used in the field experiment included a King Air research aircraft operated by the U.S. National Center for Atmospheric Research, a scanning Doppler light detection and ranging (lidar) device, integrated sounding system, wind profiler and a network of surface weather stations. Digital flight data from Cathay Pacific B–747–400s operating at Hong Kong also were collected.

Principal findings of the second meteorological report generally supported the conclusions of previous studies. It indicated that moderate to severe terrain–induced turbulence occurs in the vicinity of Chek Lap Kok and that it is more frequent than terrain–induced windshear. Turbulence is found almost exclusively in a well–defined region in the wake of the surrounding terrain. Ambient wind speed determines the magnitude of this turbulence, whereas ambient wind direction governs location. Other factors, such as stability, affect the wind flow response but are secondary.

Both mechanical and gravity–wave processes appear to be important in the dynamics and the net response of both processes appears to be quasi–linear and similar. There is no indication of resonance or unusual responses. Significant terrain–induced windshear and turbulence will occur in episodes that are typically several days in duration and separated by several weeks.

The wealth of scientific information provided by the field study was used in the design of the WTWS system. Coupled with feedback from controllers, pilots and aviation meteorologists, this information was used to develop an operational concept for the new alerting system.

Engineering Design

WTWS graphical display

Designers developed the WTWS products to enhance the safety, capacity and efficiency of operations at Chek Lap Kok by automatically providing pilots with concise windshear and turbulence alerts. The system also was designed to provide air traffic managers and supervisors with information to aid effective decision–making and to present high–resolution, real–time meteorological data and forecast guidance to forecasters.

The WTWS integrates data from various sensors and sources, including anemometers, Doppler weather radar, Doppler wind profilers, numerical weather prediction models and an array of global weather observations. Indirectly, it receives data from the ICAO world area forecast system (WAFS) and the World Meteorological Organization (WMO) global telecommunications system.

To enhance flexibility, the system was designed to run on commercially available Unix platforms. Modular system software, written in the C and Fortran programming languages, was designed to conform to international standards, allowing WTWS to run on vendor–neutral platforms. To heighten reliability, a redundant array of independent computers environment was employed. This ensures that all critical system processes are running somewhere on a network of WTWS computers. The capability to refine or tune system algorithms after, as well as before, installation is an important feature because optimization can be achieved only after it is used in an operational environment. The system also includes provisions for accommodation of new types of data, such as real–time aircraft and lidar data, after initial deployment.

An advanced version of the mesoscale model (MM5) developed by Penn State University and NCAR is used to predict atmospheric conditions around the new airport. The MM5 modelling system was adapted to provide real–time, short–range prediction of the mesoscale atmospheric conditions conducive to terrain–induced windshear and turbulence.

Although the MM5 produces weather guidance for the entire Hong Kong region, airport–specific forecasts are generated with a post-processing algorithm. Similar to model output statistics (MOS) techniques commonly used at major forecast centers, this algorithm provides 12–hour forecasts with 30–minute resolution of wind and turbulence at Chek Lap Kok.

The WTWS algorithms, many of which utilize an analysis technique known as 'fuzzy logic', produce turbulence and windshear products based on sensor data. This technique makes use of disparate data types and keeps important information throughout the decision process, maximizing algorithm performance. Sensor inputs include automatic weather stations, TDWR, and an aerodrome meteorological observing system – and each is used by specific windshear and turbulence detection algorithms. The weather product algorithms are used to produce gridded information, which is integrated using decision algorithms. By employing such a scheme, a new turbulence or wind shear algorithm can be added to the system by tailoring its output to a standardized format.

Radar-based Wind Shear Alert System

Wind shear experts in RAL provide consultancy services to public and private organizations and governments around the world to help them understand wind shear and various wind shear detection system solutions. The consultancy services include identifying the exposure to wind shear, providing technical information on wind shear detection system solutions, siting systems, training aviation personnel on the impacts of wind shear on aviation, preparing technical specifications for wind shear systems, supporting the tendering process, and assisting with the implementation of wind shear detection solutions.

The Research Applications Laboratory (RAL) of NCAR has over twenty years of experience in system development and technology transfer. NCAR/RAL has successfully developed and transferred to operations weather decision support technologies to the aviation community (e.g., airlines, Federal Aviation Administration (FAA), National Weather Service (NWS), international governments (Taiwan, Hong Kong, Korea, Australia, United Arab Emirates, Singapore, and others), private sector companies, Army, Air Force, Defense Threat Reduction Agency (DTRA), Pentagon Force Protection, National Ground Intelligence Center (NGIC), Department of Homeland Security (DHS), Department of Transportation (DOT), National Aeronautics and Space Administration (NASA), and many other clients. As a national center, NCAR is able to utilize advancements developed not only at NCAR, but at research centers, universities, and national laboratories worldwide.

NCAR/RAL has extensive experience in aviation weather. This experience in aviation weather has emphasized

1. Expert knowledge in aviation weather science
2. The development of aviation weather decision support systems that make weather information easy to use in operational environments
3. The development of detection and forecast algorithms, methods, and techniques which generate aviation specific information
4. the use of specialized models and data systems to improve the accuracy of detections and forecasts.

Significant aviation-weather research and development experience includes the following:

1. Joint Airport Weather Studies (JAWS) Project – This was an NCAR–directed research project in the 1980s in which physical processes associated with thunderstorm–initiated downbursts and wind shear were investigated. The knowledge gained served as the basis for future development of airport wind shear detection systems.
2. Low–Level Windshear Alert System (LLWAS) – NCAR developed this first airport wind shear alert system for detecting microbursts. Over 110 systems have been installed in the US to assist in providing warnings of microburst and gust–front–related low–level wind shear. This technology has also been implemented at airports worldwide. NCAR holds the patent for LLWAS wind shear detection algorithms.
3. Terminal Doppler Weather Radar (TDWR) – Convective weather research and prototype development at NCAR in the 1980s and 1990s strongly influenced the design, scanning strategies and end–user products generated by this aviation–weather radar system that was installed at 50 major airports in the US. NCAR also holds the patent for algorithms integrating TDWR and LLWAS data. NCAR's prototype TDWR system was successfully used to protect Denver's Stapleton Airport from wind shear for six years until the operational TDWR took its place at Denver International Airport.
4. Terminal–Area Surveillance System (TASS) – The TASS was a next–generation (electronic scanning) airport radar surveillance system prototype that was designed to track aircraft as well as weather and weather hazards. NCAR developed prototype weather hazard detection algorithms for this system, including those that detect microbursts and other wind–shear–related phenomena.
5. Aviation Weather Research Program (AWRP) – The AWRP is a 20 year research and development program supported by the US Federal Aviation Administration (FAA) in which NCAR is a major participant. The objective of the AWRP is to develop improved detection and forecasting techniques for all weather factors that influence aviation safety and efficiency, including turbulence, icing, snowfall, convective weather, cloud ceiling, and visibility.
6. Convectively Initiated Precipitation Research – Automated nowcasting techniques have been developed at NCAR for the very short range (0 to 2 hour) prediction of convective precipitation and related hazards near airports.
7. Wind Shear Detection and Warning System (WTWS) – NCAR designed, developed, tested, and installed an operational wind shear and turbulence detection and forecast system for Hong Kong International Airport, which was constructed in a location that experiences terrain–induced windshear that is potentially hazardous to aircraft. In order to enhance the safety of aircraft operations at the new airport, the WTWS was developed to detect, forecast, quantify, display and provide warnings for significant terrain–induced and convective windshear and turbulence. Components of this system include automated surface sensing systems, a Terminal Doppler Weather Radar, and wind profilers. Doppler lidar systems were recently added to the WTWS by the Hong Kong Observatory as a system enhancement.
8. Advanced Operational Aviation Weather System (AOAWS) – NCAR developed an advanced aviation weather system for the Taiwan Civil Aeronautics Administration to cover the Taipei Flight Information Region (FIR). The AOAWS includes advanced aviation weather prediction capabilities, turbulence and icing algorithms, and flight planning tools. The AOAWS also includes wind shear detection systems at Songshun Airport and TTY International Airport.
9. Aeronautical Meteorology System Technical Assistance Unidad Administrativa Especial de Aeronautica Civil (UAEAC), Colombia, South America – NCAR teamed with Earth Satellite Corporation in 2005 to perform a detailed assessment of the current state of the Colombian Aeronautical Meteorology System. NCAR performed airport site visits, assessed the current aviation weather infrastructure, and developed a phased development plan for modernizing the Colombian aeronautical Meteorology system. This consultancy included an assessment of windshear and turbulence technologies as well as other aviation hazards.
10. Juneau Airport Wind System – NCAR developed a sophisticated wind information system for Juneau Airport that provides terrain–induced windshear and turbulence alerts for specific aircraft arrival and departure corridors. This FAA funded system incorporates data from anemometers near the runways and on nearby mountaintops, and data from wind profilers.
11. Assessment of Meteorological Services – Kingdom of Saudi Arabia – At the request of the Presidency of Meteorology and Environment (PME), NCAR conducted a study to assess the current status of PME meteorological services including aeronautical meteorology, forecasting operations, radar systems, and their air quality program. NCAR provided recommendations regarding how the PME could modernize its capabilities over five–year and ten–year periods.
12. Sydney Airport Wind Shear Consultancy – Between 2009 and 2010, NCAR wind shear system experts performed a detailed study of wind shear detection system technologies that are appropriate for Sydney International Airport and other sites across Australia. This study provided as assessment of several technologies including Doppler weather radar, Doppler lidar, Low-Level Wind Shear Alert System (LLWAS), sodar, wind profiler, and combinations of these technologies. This study was performed for a team of aviation stakeholders including the Bureau of Meteorology, airlines, Airway Services of Australia, and the Sydney Airport Authority.

NCAR has demonstrated its ability and willingness to share its research results with aviation weather stakeholders. This enables results to be quickly communicated and implemented into operations to support decision makers. NCAR's commitment to the development and long–term support of a suite of open–source sophisticated technologies (e.g., weather models, algorithms, decision support systems, etc.) has transformed the scientific and engineering fields and has contributed to technical advancements throughout the nation and world.

The Research Applications Laboratory is addressing oceanic weather needs for aviation through the development of an intelligent system that generates 0-2 hour nowcasts.

Examples of the CTH and CDO polygon products

 

Examples of the CTH and CDO gridded products

Remote, oceanic regions have severely limited data availability and therefore, have few, if any, high resolution weather products that indicate current locations of convection. Convective hazards impact the safety, efficiency and economic viability of oceanic aircraft operations by producing turbulence, icing and lightning and by necessitating aircraft rerouting while in-flight, leading to higher fuel costs and delays. The Research Applications Laboratory is addressing oceanic weather needs for aviation through the development of convection diagnostic products. These products are the Cloud Top Height (CTH) and the Convection Diagnosis Oceanic (CDO). Both use geostationary satellite data as a primary input with the CDO also utilizing lightning data. These two products focus on the needs of pilots, dispatchers, air traffic managers and forecasters within the oceanic aviation community.

Prototype CTH/CDO products are now available. To request data access visit the tab above "Data Access".

cdo-info@rap.ucar.edu

The Remote Oceanic Meteorology Information Operational (ROMIO) Demonstration

RAL Benefits & Impacts: Avoiding Dangerous Weather Oceanic Flights:

Remote Oceanic Met Info Operational (ROMIO)

Images

CONVECTIVE WEATHER HAZARDS DISPLAY

• 3-Satellite Full Disk Domain

HOURLY EXTRAPOLATION FORECASTS

• 3-Satellite Full Disk Domain Loops

CLOUD TOP HEIGHT DISPLAY

• Atlantic Ocean
  • Gulf of Mexico
  • North Atlantic
• Pacific Ocean
  • South Pacific
  • Hawaii
• Continental USA
• GOES-East fullDisk
• GOES-West fullDisk
• GOES-East & GOES-West mosaic

ITCZ REGIONS: ATLANTIC, SOUTH PACIFIC, CENTRAL PACIFIC

• Movie Loops

CONVECTION PRODUCT SUITE

• Gulf of Mexico

• Eastern USA

CLOUD TOP HEIGHT (CTH)

The Cloud Top Height (CTH) product combines geostationary satellite Infrared data and numerical weather prediction output to create a detailed diagnosis of the estimated heights of convective cloud tops over the open ocean.

The Cloud Top Height (CTH) product combines geostationary satellite Infrared data and numerical weather prediction output to create a detailed diagnosis of the estimated heights of convective cloud tops over the open ocean. Provided that clouds are of sufficient optical thickness such that transmission from the lower atmosphere may be safely neglected (such as occurs within deep convection), the emitting temperature of the cloud across the ~11.0 micron window channel is assumed to be representative of the ambient environment. Soundings generated by the National Center for Environmental Prediction (NCEP) Global Forecasting System (GFS) numerical model are employed to convert the satellite brightness temperatures to flight-level altitudes (expressed in Kilo-feet). Specifically, the CTH makes a conversion from satellite brightness temperature to the equivalent GFS pressure surface. This pressure level is then used to interpolate to a standard atmosphere height. Similarly, aircraft altimeters also convert a pressure measurement to an equivalent altitude using the standard atmosphere.

The product performs for both day- and night-time hours and gives valid results for clouds with tops at and above 15,000 feet.

The Naval Research Laboratory in Monterey, CA (NRL-MRY) originally developed the CTH algorithm. The following reference applies:

Donovan, M.F., E.R. Williams, C. Kessinger, G. Blackburn, P.H. Herzegh, R.L. Bankert, S. Miller, and F.R. Mosher, 2006: The identification and verification of hazardous convective cells over oceans using visible and infrared satellite observations, Preprints-CD, 12th Conference on Aviation, Range and Aerospace Meteorology, AMS, Atlanta, GA, 30 January-2 February 2006.

REFERENCES

Bedka et al., 2010: Objective satellite-based detection of overshooting tops using infrared window channel brightness temperature gradients, J. Appl. Meteor. Clim., 49, 181-202.

Donovan et al., 2008: The identification and verification of hazardous convective cells over oceans using visible and infrared satellite observations, J. Appl. Meteor. Clim., 47, 164-184.

Donovan et al., 2009: An evaluation of a Convection Diagnosis Algorithm over the Gulf of Mexico using NASA TRMM Observations. 16th Conf. Satellite Meteor. Ocean., Amer. Meteor. Soc., Phoenix, AZ, 12-15 Jan 2009.

Frazier, E., C. Kessinger, T. Lindholm, J. Olivo, B. Barron, G. Blackburn, B. Watts, R. Stone, D. Keany, D. Tyler and T. J. Horsager, 2017: The Remote Oceanic Meteorology Information Operational (ROMIO) Demonstration. World Meteorological Organization, Proceedings of the 2017 WMO Aeronautical Meteorology Scientific Conference, Toulouse, France, 6-10 November 2017, pages P2-94:P2-102.

Kessinger, C., et al., 2015: Demonstration of a Convective Weather Product into the Flight Deck. 17th Conf. Aviation, Range and Aerospace Meteorology, Amer. Meteor. Soc., 4-8 January 2015, paper 13.4.

Kessinger, C., et al., 2017: The global weather hazards project. 18th Conf. Aviation, Range and Aerospace Meteorology, Amer. Meteor. Soc., 23-26 January 2017, paper 9.3.

Kessinger, C., D. Megenhardt, G. Blackburn, J. Olivo, L. Lin, V. Hoang, M. Nayote, K. Sievers, A. Ritter, D. Wolf, O. Matz, R. Scheinhartz and J. Cahall, 2017: Displaying convective weather products on an electronic flight bag, The Journal of Air Traffic Control, 59 (3), 52-61.

Kessinger, C., 2017: An update on the Convection Diagnosis Oceanic Algorithm, 18th Conf. on Aviation, Range, and Aerospace Meteorology, American Meteorological Society, Seattle, WA, 22-26 Jan. 2017, poster 211.

Kessinger, C., E. Frazier, T. Lindholm, B. Barron, J. Olivo, B. Watts, R. Stone, S. Abelman, A. Trani, M. DeRis and C. Gill, 2019: “The Remote Oceanic Meteorology Information Operational (ROMIO) Demonstration”, 19th AMS ARAM Conference, 7-10 Jan 2019, Phoenix, AZ.

Kessinger, C., E. Frazier, A. Izadi, A. Trani, T. Lindholm, J. Olivo, B. Watts, R. Stone, B. Norris, S. Abelman,  E. Senen, and K. Bharathan, 2020: “Remote Oceanic Meteorology Information Operational (ROMIO) Demonstration”, 20th AMS ARAM Conference, 12-16 Jan 2020, Boston, MA, paper 12.1.

Miller, S., et al., 2005: Technical Description of the Cloud Top Height (CTOP) Product, the first component of the Convective Diagnosis Oceanic (CDO) Product. Submitted to FAA AWRP, 11 March 2005, 30 pp.

Mosher, 2002: Detection of deep convection around the globe. Preprints, 10th Conf. Aviation, Range, Aerospace Meteor., Amer. Meteor. Soc., Portland, OR, 289-292.

Funding

Federal Aviation Administration (FAA)

NCAR's demonstration system merges NTDA output from multiple radars to form a 3–D turbulence map, revealing regions of moderate and severe turbulence within clouds and thunderstorms.

166 FAA, NWS and DoD NEXRADs are currently in operation, providing Doppler wind and wind variability measurements as well as the more familiar reflectivity. The NTDA is a software upgrade that uses these data to detect in–cloud turbulence before aircraft encounter it.

Making use of the wind variability data provided by Doppler weather radars, RAL scientists have developed and tested the NCAR Turbulence Detection Algorithm (NTDA), designed for use on the nation's network of NEXRAD radars. The NTDA utilizes NEXRAD Level II data – the reflectivity, radial velocity, and spectrum width – to perform data quality control and produce atmospheric turbulence intensity (eddy dissipation rate, EDR) measurements of "in–cloud" turbulence. The expert system combines multiple modules for quality control and turbulence estimation using a "fuzzy logic" methodology to produce a final EDR and associated quality control index, or confidence. By providing direct detection of turbulence, NTDA provides an important addition to radar reflectivity as an indication of in–cloud aviation hazards. NTDA development has been funded by the FAA's Aviation Weather Research Program.

Example of text–based graphic used in uplink demonstration.

The first version of the algorithm, NTDA–1, was delivered to the NWS Radar Operations Center and deployed on all NEXRADs in 2008. The next version, NTDA–2, accommodates recent NEXRAD changes and is targeted for deployment in the 2012–2013 timeframe. A prototype version, running in real–time at NCAR, processes Level II data from 133 NEXRADs around the U.S. and produces a 3–D mosaic of in–cloud EDR updated every 5 min. In addition to possible direct use by pilots, airline dispatchers and air traffic control meteorologists, the NTDA data are being incorporated into a new Graphical Turbulence Guidance Nowcast (GTGN®) product. Given the highly transient and spatially variable nature of in–cloud turbulence, maximum benefit of the NTDA product can be achieved if pilots can receive this information in the cockpit in nearly real time. This capability has been demonstrated in collaboration with United Airlines: character graphics depictions of in–cloud turbulence 100 miles ahead and 40 miles to either side of the planned route were uplinked to selected United Airlines flights via ACARS. Pilots indicated that this information could be very useful for making tactical decisions near storms, suggesting that this product could improve airline safety while reducing delays due to unneeded deviations.

The LLWAS system was originally developed by the FAA in the 1970s to detect large scale wind shifts (sea breeze fronts, gust fronts and cold and warm fronts). It was developed by the FAA in response to an accident at JFK airport in New York. The aircraft (Eastern 66) landed during a wind shift caused by interacting sea breeze and thunderstorm outflows.

Artist rendition of a microburst and its effect on a landing aircraft.

This Phase–1 LLWAS was very simple. It compared a center field wind to 5 other sensors around the airport. When there was a 15–knot vector difference, it would flash the wind data to the air traffic controller and the controller would read the raw winds, e.g., 120/35 (120 degrees at 35 knots), 110/20, 350/15, etc. from each sensor to the pilot landing or about to take off and the pilot had to do the vector addition in his head to determine the headwind/tailwind components.

This simple system worked for large scale weather features, but it also had a serious false alarm problem and the sensors were too far apart to capture small, but intense windshear events important to aircraft. Also, the center field wind could be variable and this would trigger windshear alarms at all the outer sensors since all the other sensor winds were compared to center field. Research conducted at the National Center for Atmospheric Research (NCAR) in the 1980s indicated that microburst windshear was very dangerous to aircraft below 1000 ft. Several major accidents during the 1980s also implicated windshear as a factor.

LLWAS History

In 1983, the FAA asked NCAR to develop a version of LLWAS that could detect microbursts. Between 1983 and 1988, NCAR developed and tested a new LLWAS system, called enhanced LLWAS or LLWAS–Network Expansion that detected microbursts, determined the strength in terms of headwind/tailwind gains or losses (in knots) and located the event (on the runway, at 1, 2, or 3 nm on departure or arrival). The system was designed to provide alerts specific to each runway operation. It was designed to have a probability of detection of 90 percent or greater and a false alarm rate of 10 percent or less.

This system was later improved and is now called the Phase–3 LLWAS. A typical Phase–3 LLWAS will have enough sensors to be spaced 2–km apart (∼1 nm apart) and cover out to 2 nm from the end of each major runway. The largest LLWAS is at Denver International Airport. It has 32 wind sensors. Most Phase–3 systems have between 12 and 16 wind sensors. A siting evaluation is done for each airport to determine the network geometry since it depends on terrain, # of runways, obstructions, etc.

The Phase–3 LLWAS alert information is described here. If a pilot is landing on runway 08, and there is a microburst on his path, the controller would have a display that reads: 08A MBA 30K–3MF 350/25. This is read to a pilot arriving on runway 08 (08A) by a final controller as "microburst alert (MBA), expect a thirty knot loss (30K–) at three miles final (3MF), threshold wind three–five–zero at 25 (knots)".

If there was a wind shear with a wind speed gain at 1 mile departure (headwind gain), for a pilot departing runway 25 left, the final controller's LLWAS display would show: 25LD WSA 15k+ 1MD. This would be read as "winds hear alert, expect a fifteen knot gain at one mile departure". There are Phase–3 LLWAS systems at 9 US airports and Phase 2 LLWAS at more than 100 airports. Taiwan, Korea, Singapore, Saudi Arabia, and Kuwait are now implementing LLWAS Phase–3 systems. Note, the FAA also has Terminal Doppler Weather Radars for wind shear detection at 45 airports and has ASR–9 based wind shear detection systems at another 37 airports. The FAA originally had 110 Phase–1 LLWAS systems, which were upgraded to Phase–2 systems.

A Phase–2 LLWAS has the same number of sensors (5–6) as a Phase–1 system (described above), but the wind shear algorithm was upgraded to significantly decrease the number of false alarms. As mentioned above, a Phase–1 or Phase–2 LLWAS was not designed to detect microbursts per se, but if the flow is large and strong, it may alert.

When NCAR developed the Phase–3 LLWAS, it gave the specifications to the FAA. The University Corporation for Atmospheric Research Foundation (UCARF),  owned the intellectual property for the wind shear algorithm during the lifetime of the patent. A license agreement was required for companies to implement LLWAS technology until early 2013 when the patent exclusion expired. A license from UCARF is no longer required to utilize the LLWAS algorithm. The UCARF does however, provide technical materials such as test datasets, test airport configuration files, test alert outputs, etc. to aid companies in the implementation and testing of the LLWAS Phase-3 algorithm.

Consulting

Wind shear experts in RAL provide consultancy services to public and private organizations and governments around the world to help them understand wind shear and various wind shear detection system solutions. The consultancy services include identifying the exposure to wind shear, providing technical information on wind shear detection system solutions, siting systems, training aviation personnel on the impacts of wind shear on aviation, preparing technical specifications for wind shear systems, supporting the tendering process, and assisting with the implementation of wind shear detection solutions. For more information go to our page on wind shear system consultancy services.