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The Forecast Research Division comprises three branches:

• Regional Analysis and Prediction Branch (RAP)
  
• Local Analysis and Prediction Branch (LAPB)
  
• Meteorological Applications Branch (MAB).

The Regional Analysis and Prediction Branch develops and supports the following research programs:

Rapid Update Cycle (RUC) – A complete analysis/forecast system for hourly assimilation of meteorological observations over the United States into a numerical prediction model, the RUC has been implemented as an operational forecast system at the National Centers for Environmental Prediction (NCEP). The branch develops and tests improvements to the RUC and its research counterpart, the Mesoscale Analysis and Prediction System (MAPS), in the following areas:
• Data Assimilation – Improved techniques for estimating meteorological parameters on a regular grid, combining information from in situ and remote observations with that from a forecast model. Investigation of uses for new data sources.

• Numerical Prediction – Design, testing, and implementation of improvements to the RUC/MAPS numerical prediction model, with a major emphasis on improving representation of processes near the surface and in clouds, which exert a strong control on mesoscale forecasts.

• Analysis and Model Verification – Statistical and subjective evaluations of RUC/MAPS analysis and forecast products for standard atmospheric variables, surface conditions, aviation-impact variables, clouds, and precipitation.

• Data Sensitivity Studies – Studies conducted, using the RUC, to determine the effects of different types of observations on short-range numerical forecasts.

Well-Posed Model – Development of an accurate multiscale, limited-area forecasting model that is not sensitive to errors in the initial, boundary, and forcing data.

Local Analysis and Prediction System (LAPS) – Incorporation of new datasets into numerical models for the production of very detailed analyses of local weather conditions and short-range forecasts. The model is updated with new observations at least hourly. LAPS plays a major role in FSL's Aviation Program, particularly in diagnosing and predicting aviation terminal weather.

LAPS Observation Simulation System (OSS) – Evaluation of new observation technology or siting of existing observational systems. This system has been employed to assess the potential of new satellite systems for the Department of Defense (DOD) and instrument placement around eastern and western space centers of the U.S. Air Force and the National Aeronautics and Space Administration (NASA).

Satellite Products – Development and evaluation of workstation products derived from atmospheric soundings aboard the Geostationary Operational Environmental Satellite (GOES). WFO-Advanced Support – Full support of an operational version of LAPS on the WFO-Advanced workstation, including both analysis and prediction. The WFO-Advanced forecaster workstation is used to demonstrate Advanced Weather Interactive Processing System (AWIPS) functions in support of future Weather Forecast Office (WFO) operations.

The Meteorological Applications Branch conducts research to increase the understanding of synoptic-scale and mesoscale weather systems. Scientists develop and improve conceptual and diagnostic models of the atmosphere using data from conventional instruments and new state-of-the-art sensors. Many research results are applicable to operational weather forecasting. Specific research areas under investigation are:

GAINS Project – Investigation of a concept for routinely sounding Earth's atmosphere over oceanic areas, as in the Global Air-Ocean IN-situ System (GAINS) program.

Diagnostic Turbulence Forecasting – Development, testing, and verification of numerical weather model computer code and parameterizations for forecasting variables of interest to aviation, especially turbulence.

Research Quality Datasets – Production of hourly precipitation data, North American radiosondes, and meteorological data from commercial aircraft (ACARS) on CD-ROMs and the Web.

Real-Time Precipitation Gauge Observations – Assessments of and improvements to the set of hourly precipitation measurements utilized for verification purposes by the Real-Time Verification System (RTVS).

ACARS Quality Control System – Development of and upgrades to a computer program to flag and correct weather data from automated sensors (ACARS) on commercial aircraft.

Potential Vorticity Streamers – Studies of the dynamic link between potential vorticity on the synoptic scale and heavy precipitation in mesoscale systems.

Websites for FSL Data – Development of Websites for ACARS data, interactive soundings from the MAPS/RUC-2 forecast model, satellite image loopers, and other data.

The RUC has a unique role within the NWS in that it is the only operational system that provides updated national-scale numerical analyses and forecasts more often than once every 6 hours. It was developed in response to the needs of the aviation community and other forecast users for high-frequency, mesoscale analyses and short-range forecasts covering the conterminous United States. It is a critical part of the NWS modemization program, and has become widely used in NWS Forecast Offices, NWS centers for aviation weather and storm prediction, the FAA, and other facilities. Evaluations of the RUC have clearly demonstrated its advantage in providing high-frequency, recently initialized forecasts based on the latest observations. The RUC is a key part of the Aviation Weather Program, since commercial and general aviation are both critically dependent on accurate short-range forecasts. The RUC will continue to improve over the next several years, perpetuating the successful collaboration between FSL and NCEP.

In collaboration with other government agencies (e.g., NCAR, NESDIS) and universities (e.g., University of Miami, University of Oklahoma), scientists develop improved data assimilation and modeling methods foruse in the RUC. New datasets are assimilated as they become available, so that all potentially useful observations can be incorporated to define the current atmospheric and surface conditions, thereby producing the most accurate forecast possible. The branch also interacts with other FSL staff in implementing optimal computing methods with RUC software, making the model as efficient as possible on modem computing platforms.

Following the implementation of the 40-km RUC-2 at NCEP in April 1998, scientists in the RAP Branch have worked on development of a new version of the RUC planned for implementation at NCEP in late 2001. The higher horizontal resolution of the new version takes advantage of the improved computing capability at NCEP on its IBM SP computer. This new version has four key aspects: finer (20-km) horizontal and vertical (40 – 50 levels) resolution (requiring about 10 times the computations ofthe 40-km version for the forecast model), an improved version ofthe RUC forecast model, assimilation of GOES-based cloud-top pressure to improve the initial RUC cloud and precipitation fields for each forecast, and use of a three-dimensional variational analysis (3DVAR), replacing the current optimal interpolation analysis.

Resolution and Domain – The increase in horizontal resolution to 20 km provides considerable improvement in accounting for the effects of topography and land-surface variations on wind and precipitation. In addition to much improved orographic precipitation forecasts, the smaller grid volumes in the 20-km RUC allow improved depiction of cloud and more representation of mesoscale convective cloud/precipitation systems at the resolved grid scale. These smaller grid volumes also improve the ability of the RUC to resolve clouds and areas with super-cooled liquid water with potential for icing. The 20-km resolution also allows the RUC to better delineate areas with potential for turbulence, whether of clear-air, mountain-wave, orconvective origin. The 20-km RUC uses 50 vertical levels, with 7 levels added in the upper troposphere and 3 in the lower troposphere. It continues to use the same hybrid isentropic/terrain-following coordinate used successfully in previous versions. In the 20-km version, the isentropic spacing is 2-3 K for reference potential temperature from 270 – 352 K. The top level is now at 500 K (approximately 40 – 60 hPa). The spacing near the surface is 2, 5, 8, and 10 hPa in the first 4 layers, with an explicit model calculation level at 5 in above the surface.

Improvements to the 20-km RUC Forecast Model – The 20-km RUC forecast model has incorporated many improvements that, even without the change in horizontal resolution, result in better RUC forecasts. The key areas of improvement are:

• Improved convective (subgrid-scale) precipitation from an ensemble closure/feedback convective parameterization by Grell and Devenyi, including effects of shallow convection, and fixes to problems with the model interface to the convective scheme. The Grell/Devenyi scheme currently uses 8 closure assumptions and 9 feedback assumptions, as implemented in the 20-km RUC model. This scheme also detrains cloud water and ice directly to the RUC cloud microphysics, a feedback absent in the 40-km RUC.
  
• Revised version of explicit mixed-phase cloud microphysics used in the RUC and MM5 in collaboration with NCAR/RAP. The key changes in the RUC microphysics are improved representation of supercooled liquid water, reduced exaggerated amounts of ice/graupel, and improved forecast precipitation type at the surface.
  
• Improvements to the land-surface/vegetation/snow model, including provision for frozen soil and a 2-layer representation of snow, and much more detailed land-surface data. The previous land-use and soil datasets used in the 40-km RUC were from 1-degree resolution data, whereas the 20-km datasets are aggregated from 1-km resolution data. The RUC land-surface model has been tested extensively in long-term one-dimensional simulations, which show that the frozen soil and snow model changes will decrease surface temperature biases in transition seasons. The prescribed values for thermal conductivity are also changed, leading to a more accurate diumal cycle for soil temperature.

These changes in the 20-km RUC forecast model have led to some significant improvements in near-surface and precipitation forecasts. The 40-km RUC has had some underestimate ofthe diurnal temperature cycle, but this problem is much reduced in forecasts from the 20-km RUC (Figure 1). This change results from the improved land-surface model, improved cloud fields, and an improved diagnosis of 2-m temperature in the 20-km RUC. Precipitation predictions of heavier amounts are important for severe weather and hydrological forecasting, but have been underestimated in the 40-km RUC. The 20-km RUC provides substantial improvement in these forecasts as shown in Figure 2, with a much improved equitable threat score (at all precipitation thresholds from 0.5 inches/24 hours and above) and bias score at all thresholds.

The RUCIMAPS Website (http://ruc.fsl.noaa.gov) – Continued enhancements were made to the RUC/MAPS Website, including products from the test version of the 20-km RUC, and the use of the 20-km RUC grids in the FSL interactive sounding program.

Development of the Well-Posed Model – Work continues on the development of a well-posed fourth order accurate limited area model. As the final step in showing how to apply the Bounded Derivative Theory to atmospheric flows evolving on the adjective timescale anywhere on the globe, a manuscript has been submitted to the open literature which shows that slowly evolving equatorial motions at any length scale satisfy the same balance between the vertical velocity and heating as in the midlatitude mesoscale case (earlier publication). Thus, any gravity waves that are generated at the equator play only a minor role in the evolution of the associated storm; for example, Bounded Derivative Initialization (BDI) can be applied to the initial data to ensure that the fast waves will be removed from the ensuing solution without significant impact on the storm. The research shows how the projection of equatorial data onto the normal modes of the adiabatic system is misleading as to the amount of energy in equatorial gravity waves. The inappropriate projection of the dominant component of the solution onto gravity waves by this method is the source of the confusion about the relative importance of latter waves. Current research also shows how BDI can be applied to multiscale flows in a global model or in an open boundary limited-area model anywhere on the globe. In addition, FSL is collaborating on a project to apply these initialization techniques to the Canadian global weather forecasts.

Complete Implementation of the 20-kilometer RUC – This higher resolution version is expected to improve RUC accuracy in many areas, especially for cloud, precipitation, and surface forecasts.

Continued Development of a National-Scale Cloud Analysis – Development and real-time testing will continue for further improvements to the RUC national-scale cloud analysis, with the addition of radar and surface observations to satellite cloud-top data. Experiments will be carried out testing assimilation of a GOES imager-based multilevel cloud product.

Refinement and Testing of Improved Physical Parameterizations for Soil/Vegetation Processes, Turbulence, Convective Clouds, and Cloud Microphysics – Some of this work will be done in collaboration with NCAR, since the RUC model uses some MM5 parameterizations. Also, some of these same parameterizations will be options for the WRF model.

Development of the Three-Dimensional Variational Analysis – Development and real-time testing will continue on the 3DVAR analysis, both for incorporation into the RUC and toward the development of the 3DVAR analysis for the WRF model.

Testing of the Nonhydrostatic Generalized Vertical Coordinate Model – Testing of this model will continue, in collaboration with the University of Miami and NCAR, as part of FSL's contribution to the overall multiagency development of the WRF model.

Other Activities

Observation Sensitivity Experiments Using RUC for the PACJET Experiment – RUC cycles will run with and without special observations designed to improve mesoscale forecasts of winds and precipitation along the United States West Coast in winter storms. A 10-km RUC model will run in a nest inside these domains, allowing improved prediction of orographic effects.

Participation in GEWEX – Collaboration will continue on the GEWEX/GAPP program, with the focus on development of a coupled atmospheric/landsurface assimilation system that uses an optimal combination of radar and satellite observations to modify clouds and precipitation along with model forecasts in regions where observations are unavailable.

Contribution of RUC 60-hour Forecasts to an NCEP Short-Range Ensemble Forecast – As part of an expansion to NCEP's Short-Range Ensemble Forecast (SREF) project, FSL will set up a version of the RUC model to run out to 63 hours on a 40-km grid over the North American Eta domain.

Development of the Well-Posed Model – Research will continue on the Well-Posed Model's Bounded Derivative Initialization applications.

The branch is charged with the research and development of the Local Analysis and Prediction System (LAPS) and the implementation of mesoscale forecast models. The primary objective is to provide real-time, three-dimensional, local-scale analyses and short-range forecasts (0 – 24 hours) for operational weather offices or facilities. Activities cover four broad areas:

Data Acquisition – Includes identifying, collecting, and quality-controlling any kind of atmospheric or earth surface measurement, such as those provided by satellites, radars, mesonets, aircraft, GPS, balloons, and profilers. This activity also includes developing interfaces to "national" datasets, such as the gridded data services provided via the Satellite Broadcast Network (SBN) data feed and similar military systems. LAPS is coupled with the Local Data Acquisition and Dissemination (LDAD) system, which stores portable applications that retrieve and render AWIPS weather data into images and graphical displays for dissemination.

Data Analysis – Accomplished using an integrated software package containing well-documented objective analysis schemes that spatially represent atmospheric conditions, perform spectral filtering, and ensure vertical consistency. This analysis capability has been demonstrated in National Weather Service (NWS) forecast offices as part of the AWIPS Application Software Suite, and in global windows to support Department of Defense (DOD) operations. A prototype system has been developed in conjunction with Lockheed and Raytheon Systems Corporation for installation at the space launch centers at Vandenberg Air Force Base and Cape Canaveral.

Mesoscale Model Implementation – Accomplished using an expanding variety of mature nonhydrostatic modeling systems, such as the Regional Atmospheric Modeling System (RAMS – developed at Colorado State University), the FSL-developed parallel version of RAMS termed the Scalable Forecast Model (SFM), MM5 (the Mesoscale Model developed jointly by NCAR and Pennsylvania State University), and the hydrostatic version of Eta developed at the National Centers for Environmental Prediction (NCEP). These models have been configured to be initialized by LAPS analyses and with time-dependent boundary conditions furnished by all operationally available gridded datasets (RUC, Eta, Aviation, and the U. S. Navy Operational Global Atmospheric Prediction System (NOGAPS)). Implementation of the LAPS system at some NWS forecast offices has demonstrated the portability and effectiveness of running models locally. FSL's collocation with the Denver-Boulder National Weather Service Forecast Office has demonstrated the effectiveness of locally run models throughout the past few years, as LAPS initialized mesoscale models have been run on their local AWIPS hardware and on FSL's High-Performance Computing System for operational evaluation.

Dissemination – Includes delivery of weather products and basic fields developed from LAPS to users in operational forecast offices and state and local government agencies, including emergency managers and other users specializing in fields such as ground transportation, aviation and space operations, and military operations such as those mentioned later.

The LAPS package has been incorporated as an integral element of the WFO-Advanced workstation. It now runs as an application within AWIPS and allows a variety of gridded fields to be combined with satellite imagery and radar on state- and local-scale displays. The LAPS in AWIPS serves the LDAD system operating outside the AWIPS network. The independent LAPS quality control system will supplement the LDAD quality control system to ensure that local data are monitored and properly employed. In preparation for AWIPS 5.0, running at all Weather Forecast Offices (WFOs), staff developed the capability to create and install a grid domain centered on each forecast office, and to automatically execute LAPS functions using the local datasets available at each location.

The WFO-Advanced workstation in Boulder receives MM5 model output from twice daily model runs on exactly the same grid and projection as the LAPS analysis. This permits the mesoscale model output to be displayed in a fully integrated fashion, along with radar, satellite, and surface data. Forecasters can check the quality of a model run by comparing model output with observations directly. The model is running experimentally in the Denver WFO on a system within the AWIPS application hardware suite. The model runs in automated mode with little intervention required.

U.S. Air Force Support

FSL continued to work with the U.S. Air Force Weather Agency (AFWA) in the maintenance and implementation of analysis and prediction capabilities to support operations in 14 global theaters. AFWA has taken advantage of LAPS relocatability and resizability capabilities to support operations worldwide for any contingency. The version of LAPS installed uses a three-dimensional variational method to constrain the analysis toward geostrophy while optimally matching observations. LAPS analyses are used as targets for a 6- to 12-hour MM5 nudging procedure to provide fields for model intialization. Currently, LAPS is running in the continental United States, Europe, Southwest Asia, Asia, Alaska, and tropical windows.

The LAPS branch worked on a complete shadowing system for any AFWA window that downloads AFWA data, performs a complete LAPS analysis, and initializes and runs the same version of MM5. The new HPTI system can easily support the processing requirements of this system.

The Range Standardization and Automation Project

The LAPS group continued collaboration with Lockheed Martin, Inc. to help design and build an automated data assimilation and forecast system for installation at the U.S. space launch facilities located at Vandenberg Air Force Base and Cape Canaveral. This system will make up the weather component of the larger Range Standardization and Automation (RSA) system, which must serve the needs of launch weather support, daily operations, range safety, and other activities.

Key technical recommendations were provided that will lead to long-term sustainability and simplified paths to future technology upgrades. These changes include the use of relatively inexpensive Linux PC clusters by the data assimilation and forecast system, full integration with a standard release of AWIPS for visualization, and use of the public domain MM5 forecast model. Additionally, the new LAPS diabatic initialization method was demonstrated and will be used in the system to provide improved short-range forecasts of clouds and precipitation. The LAPS Four-Dimensional Data Assimilation (4DDA) system will allow the ranges to take advantage of the varied and complex local observing systems to produce the required analyses and forecasts with very high spatial (1-km grid spacing) and temporal (30-minute updates) resolution.

Basic Analysis System Development

Three-Dimensional Variational Methods – LAPS has made progress in applying variational methods in its analysis. Using radiance models, RTTOVS [Radiative Transfer (RT) model for Television Infrared Orbiting Satellite (TIROS) Operational Vertical Sounder (TOVS)] and the newer Optical Test Transmittance (OPTRAN), radiance fields from the LAPS first guess can be compared to the actual sensed radiances and adjustments made to the moisture and temperature structure. The functional used in the moisture analysis is being expanded to include more terms and data sources. The functional now includes terms for three-layer GOES integrated water, full column GPS integrated water, and cloud data, in addition to radiance and background terms. (Web page http://laps.fsl.noaa.gov/birk/newvar.htm gives a more comprehensive review of the current functional.)

Research continues on a one-dimensional variational method, the application of the GOES imager/sounder radiances to LAPS upper-level moisture. This technique shows greater promise than using the data to describe total precipitable water, as has been attempted in the composite image trial. A 50 – 70% reduction in RMS error was consistently demonstrated when comparing LAPS with and without GOES data to the Denver RAOBS.

Another variational implementation involved development of a scheme that goes beyond geostrophic constraints. Here the analysis seeks to minimize the Eularian time tendencies of horizontal motion. The technique utilizes equations with the nonlinear terms and functions represented. The scheme improves the model initial condition, since minimized local velocity tendencies provide a smooth model start in the first few time steps. Another feature of the analysis is imposition of mass continuity over the domain with allowance made for input of cloud overhead motions derived from a separate cloud model, which operates within cloud domains defined by the LAPS analysis. The completed analysis includes three-dimensional motions that sustain the clouds and a direct feedback into the mass field via dynamic constraints.

Water in all Phases (WIAP) Analysis – A goal for LAPS is to provide a complete national-scale product that describes the atmospheric water distribution from vapor to cloud droplets to precipitation, both liquid and frozen. The Water in all Phases (WIAP) analysis will improve model initialization and offer quarter-hour, 5-kilometer resolution analyses of water species in all phases over the continental United States. This analysis will utilize all conventional data, along with satellite, radar, and GPS data. The routine is based on the LAPS cloud analysis, but then seeks to quantify all water substance. The laboratory's supercomputer, Jet, is necessary to run this analysis. Currently, 13- and 10-km hourly analyses are being generated on the CONUS scale.

LAPS Quality Control Using the Kalman Filtering Scheme – Quality control of observations is a continuing focus of LAPS analysis development. The Kalman filtering scheme allows users to optimally exploit local model output and past station trends and buddy trends to produce check values for surface stations. An aim of LAPS is to support a three-dimensional 30-minute analysis cycle. The Kalman scheme can provide a continuously updated and accurate set of observations at times when data density is poor. This is an appropriate approach where a user requires good product time continuity but has high variability in observation count from cycle to cycle.

Basic Model System Development

The FSL High-Performance Computing System (HPCS) has made it possible for the LAPS group to perform many real-time and test model runs (Figure 7). The new LAPS diabatic initialization scheme has been used to initialize real time forecast runs of the NCAR/PSU MM5 model four times per day to produce 24-hour forecasts since the summer of 2000. These grids have been provided to the Denver-Boulder NWS Forecast Office for operational use and evaluation, and feedback from the forecasters has been very positive. Additional runs using more traditional initialization techniques were also performed, and quantitative comparisons demonstrate the diabatically initialized forecasts of clouds and precipitation have significantly more skill, particularly for the 0 – 6 hour forecast period. A LAPS real time assimilation and forecast system based on this technique is being developed by the LAPS group for the RSA project and for a prototype installation at three NWS forecast offices in the Southern Region (San Antonio, Texas; Jackson, Mississippi; and Albuquerque, New Mexico). The portability of LAPS and relatively inexpensive high-performance Linux PC clusters make the LAPS analysis coupled with a mature mesoscale forecast model (e.g., MM5, RAMS, Eta, and WRF) an attractive option for improving short range explicit NWP forecasts for local operations nationwide.

Figure 10. Domain of the Regional Nature Run (RNR). a) top. Solid contours show the temperature at 5-km elevation from the ECMWF output valid 1800 UTC 14 February 1993. The contours are drawn every 4 degrees (K). The grid spacing used in the ECMWF RNR is about 62 km. b) bottom. Same as a), except from MM5 output (RNR domain) valid at the same time from a 90-hour forecast initialized at 0000 UTC 11 February 1993. The grid spacing used in the MM5 is 10 km.

The main goal of this study is to assess the impact of spaceborne lidar winds on regional forecasts and compare the results with those of the global lidar OSSE. The related activities include performing the RNR with the independent MM5 model for 11 days, 0000 UTC 11 – 22 February 1993; extracting and archiving data using the OSS; ingesting data by the RUC assimilation system; ensuring continuous assimilation of forecast for the test period; and validating RUC with lidar and nonlidar data. The RUC model is being used to test the impact on its forecast with simulated lidar data assimilated into the RUC initialization procedure. A comparison can be established between the lidar and nonlidar RUC forecasts, and similar tests can be conducted using simulated data for other instruments. Preliminary tests of the MM5 model are underway to ascertain that the RNR forecasts do not differ unreasonably from the counterpart ECMWF Nature run, from which the boundary conditions for MM5 have been taken throughout the whole execution of the run. A more quantitative comparison between the two Nature run forecasts is ongoing.

U. S. Army Profiler Assessment

The U.S. Army plans to remove balloons from the battlefield. Traditionally, artillery units used rawinsonde balloons to develop atmospheric profiles of wind and temperature (or equivalent density) to provide data to targeting algorithms. These efforts were time consuming and could compromise the tactical position. The question concerns whether a comprehensive analysis system like LAPS with mobile profiling units provides enough accuracy in temperature and winds to allow for the computation of accurate trajectories. A study using archived LAPS analyses and nonused rawinsondes will answer this question. Also under study are the systematic errors in profiling when considering downwind, crosswind, and upwind trajectories.

High-Performance Computing

The LAPS group was one of the first users of FSL's new HPCS when it became available for use in the spring of 2000. Since then, the HPCS has been a critical resource for all of the branch's numerical modeling activity as well as the national-scale Water In All Phases (WIAP) analysis project. This experience provided important feedback to the system developers and maintainers regarding configuration issues and future upgrade plans for the FSL HPCS. Also, benchmarks developed through the use of this system were used to design smaller Linux PC cluster systems that will run the LAPS analyses and model forecasts for three NWS forecast offices as well as for the RSA system.

Projections

During Fiscal Year 2001, the Local Analysis and Prediction Branch plans to:

• Continue to support LAPS in AWIPS, interacting with the AWIPS contractor, Litton PRC Inc., and the NWS to achieve this goal, and support builds in the six series.
• Continue the cooperative effort with Raytheon Inc. and Lockheed in developing the RSA weather support systems for the space flight centers at Cape Kennedy and Vandenberg Air Force Base.
• Demonstrate LAPS capabilities on the new high-performance multiprocessor, continue investigating hot start techniques, and perform an assessment on the use of 3DVAR and adjoints for local analysis.
• Develop a multimodel ensemble using the three models being run: Eta, RAMS, and MM5; determine the optimum configuration for best forecasts and user-friendly products.
• Complete control runs for the Lidar Assessment Experiment.
• Complete the WRF standard Initialization and contribute to 3DVAR/4DVAR development.
• Continue Lidar OSSE studies, and development and testing of the OSS.

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Meteorological Applications Branch
Cecilia M.I.R. Girz, Chief

Objectives

The Meteorological Applications Branch performs diagnostic studies of weather-related phenomena, including mesoscale convective systems, clear-air turbulence, and downslope windstorms. A springboard of these studies is the development of diagnostic tools that are applicable to observed fields and model gridpoint data, and that utilize statistical methods, fundamental dynamical relationships, and derived parameters relating to unobserved variables. These studies often result in products of value to forecasters and are transferred to the National Weather Service (NWS). Research quality datasets of operational sounding and precipitation data and of commercial aircraft atmospheric data are assembled to support FSL modeling and diagnostic activities, and are shared with other NOAA laboratories and NWS research groups. The branch also conducts field tests and computer simulations to study the impact of balloon-based, in situ observing systems on atmospheric and oceanic monitoring for environmental prediction and climate observations.

Accomplishments

Global Air-ocean IN-situ System (GAINS)

GAINS is an Earth observing system of 400 regularly spaced platforms from which in-situ sounding of the atmosphere and ocean, and in-situ collection of air chemistry samples can be performed. Two types of vehicles, operating between 18 and 23 km, make up the GAINS low-Earth-orbit constellation (Figure 11). Shear-directed balloons deliver the sensors in the summer hemisphere, where abundant sunshine powers the system and less intense weather systems permit maintenance of a grid of platforms. In the midlatitude and polar regions, where baroclinic weather systems force balloons out of a regular network, remotely operated aircraft (ROA) are employed. GAINS vehicle developments continue to emphasize the superpressure balloon. The objectives during Fiscal Year 2000 were to (1) develop and test the Balloon Envelope Recovery System (BERS), (2) perform preflight tests of the PIII balloon and radio systems in preparation for a 48-hour flight, (3) begin development of a pump for altitude control, and (4) quantify climate trends in current temperature and humidity datasets.

The DTF3 and DTF5 algorithms were evaluated during the Turbulence Intercomparison Experiment conducted from 16 January – 31 March 2000 (complete results are at http://www-ad.fsl.noaa.gov/fvb/rtvs/turb/archive/200001-200003/index.html). The performance of the algorithms showed a day-to-day variability in detecting positive turbulence; however, the probability of detecting negative turbulence is above 80%. Studies are also in process to investigate the conditions under which the DTF algorithms do and do not predict turbulence well. Evaluation of the prediction algorithms is difficult, because voice pilot reports (PIREPs in the U.S. and AIREPs in Europe) are the only turbulence data routinely available. To compensate for this lack, a time-space conversion was used. From GOES water vapor imagery, circulation features are identified that can be tracked and for which propagation velocities can be computed. PIREPs for an entire 24-hour period surrounding a turbulence event have been advected forward and backward relative to their timing in relation to that of the event. Using this compositing method, relationships can be seen among the weather patterns (manifested as clouds and winds in satellite imagery or numerical weather model output), the predicted turbulence, and pilot reports of turbulence. Specifically, when composited in this way, PIREPs form clusters around upper atmospheric structures such as fronts, jets, and cyclones. DTF3 forecasts of turbulence at 50-hPa intervals between 450 – 200 hPa are found to be collocated with the majority of PIREPs in a case study of 7 February 1999. Most of the misses occurred over bright regions of the water vapor satellite image, suggesting that these misses represent convection-induced turbulence. The DTF3 algorithm is not designed to detect turbulence associated with convection.

Selected turbulence cases from the National Transportation Safety Board (NTSB) database were studied for further examination of DTF3. One of three criteria has to be met for a case to be included in the NTSB database: 1) structural damage occurred to the aircraft, 2) a passenger or crew member suffered a serious injury, or 3) a person onboard the aircraft died as a direct result of the incident. Three turbulence events occurred during the period of study (26 January – 12 February 1999). Turbulence occurred in two cases as a result of shear instabilities in the atmosphere, placing the position of the report within the envelope of algorithm-predicted turbulence, or on the edge. For the third case, a meteorological analysis indicated prevalence of gravity waves in the region. This source of turbulence is not accounted for in DTF3, and so the event was not predicted. This study also indicated the sensitivity of the model to complete initialization data. In one of the shear-instability cases, wind data were missing from several NWS soundings upstream of the event of both synoptic times preceding the event. This loss of input data to the model caused the predicted winds and temperatures at the time of the event to be significantly underforecast, and, consequently, the forecast turbulence intensities were similarly underpredicted.

Research Quality Datasets

A two-CD dataset was jointly produced by FSL and the National Climatic Data Center (NCDC) encompassing 50 years of hourly rain gauge data, Hourly Precipitation Data (HPD). This dataset, archived at NCDC, was formally released and announced in the Bulletin of the American Meteorological Society. The HPD dataset encompasses all TD3240 series NCDC data from 1900 – 1997, accompanied by FSL-designed and produced access and display utilities for use on a wide variety of computing platforms. These utilities provide users with options to randomly access the HPD data, select local or universal time, and choose several popular output formats, including the one to facilitate data display using a Java-based routine. Standard Web browsers use these display routines to provide a graphical view of the data with a variety of options. After release, in response to suggestions and error reports from users, FSL continued to correct and upgrade these routines. Further information about this CD-ROM, including output examples and links to NCDC with ordering information, are available at the FSL Website http://precip.fsl.noaa.gov/hpd/. From this link, utilities to use the HPD CDs can be downloaded. Enhanced Website features, including examples of the potential output products and geographical displays available to plot the observations, were included in the site graphics.

Assessing the Quality of Real-Time Precipitation Gauge Observations

As part of an ongoing precipitation verification project, the branch continued to assess and improve the set of hourly precipitation measurements utilized for verification purposes by the Real Time Verification System (RTVS). Two procedures were established to provide a reliable set of hourly stations for short-term model verification. First, the full unfiltered set of Hydrometeorological Automated Data System (HADS) observations were collated with the daily first cut set of stations that River Forecast Centers (RFCS) introduce into the datastream of 24-hour accumulated observations. Second, recognizing that this procedure occasionally filters many stations whose observations appear valid, especially in the western and northwestern U.S., the full set of hourly stations was qualitatively examined using a parallel clustered time series of observations. Approximately 150 new stations were identified in this way in the otherwise sparsely observed north-central and northwestern U.S.

Other studies of the network of one-per-day real-time gauge observations revealed reporting characteristics that have potentially negative impact for precipitation analyses. In particular, a tendency for a significant fraction of observers in some regions to fail to report zero rainfall can bias area-averaged or median precipitation toward inaccurately large values. Figure 15 demonstrates this characteristic over about a 50,000 km2 region in the southern U.S. by showing a strong inverse relationship between the total number of stations that reported nonzero precipitation on a given day and the number of stations that are missing. As further confirmation, two days during this period, one generally rainy and one essentially dry, are shown in Figure 16. Review of the percentage of rainy days during the month at the individual stations in the region (Figure 17) showed that fully 20% of the sites have an unrealistically high percentage of rainy days, suggesting that zero days at these stations were not reported. The implication of the unreported zero observations for analyses is a bias toward grid area values that are systematically too large on days of mixed zero-nonzero precipitation.

GAINS Website (http://www-frd.fsl.noaa.gov/mab/sdb/) – Results from recent experiments and discussion of future plans have been added this year to the GAINS Webpage. A section discussing global drift simulations is also new. Links to the Fiscal Year 2000 and Fiscal Year 1998 GAINS Technical Review materials and recent conference presentations give additional information on the project's process.

National Hourly/Daily Precipitation Website (http://precip.fsl.noaa.gov/hourly_precip.html) – Staff continued to develop a Website that displays hourly and daily precipitation data from NCEP. Data are displayed on a national map that optionally shows rivers and county boundaries. Moving the cursor across the map reveals the available data, and a mouse click provides a daily time series of the data. Users can zoom and roam on the map for detailed local structure of precipitation events. Years of precipitation observations are available at the site. Simplified scripts were written to reconstruct the display datastreams for days when data delivery is delayed. The updating of metadatasets necessary for accurate plotting of precipitation observations has been automated, with help from the Facility Division.

Hourly Precipitation Data CD-ROM Utility Website (http://precip.fsl.noaa.gov/hpd/) – With release of two CDs of the hourly precipitation data (HPD) gauge observations, a local Website was opened. This Website provides utility programs to download HPD data from the CD and display these data via Web-based browsers. The site was enhanced to include in the graphics such features as examples of the potential output products and geographical displays available to plot the observations.

North American Radiosonde Database (http://raob.fsl.noaa.gov/Raob_Software.html) – This site provides access to the most recent two years of radiosonde data from the North American Radiosonde Database. Upgrades last year included the provisional data from 714 international sites that are accessible from a list of specific countries. Data can now be accessed by specific states within the U.S.

ACARS Website (http://acweb.fsl.noaa.gov/) – The following upgrades were made to this site, which displays weather data from automated sensors on commercial aircraft:

• The zooming function was completely rewritten so that each zoom generates a new Lambert conformal conic projection with one standard parallel. The standard parallel is taken as the center of the zoomed region; thus, north will always be directly up in the center of any map.

• A long-term error in wind directions was corrected both on the Java and non-Java displays. Previously, wind directions were not corrected for the angular deviation of compass directions away from the center of the projected map; for example, north winds always pointed straight up, whereas the north direction varied with longitude. With the correction, wind directions are consistent with geographic directions everywhere.

• Color coding by wind speed was added as an option, as was an additional slider bar that controls the range of wind speeds displayed.

• For soundings, the flight track is optionally shown instead of the hodograph in the soundings window.

• It is now possible to select the display of only aircraft reporting vertical gust data.

• Loading of data is more robust, and loading no longer stops when encountering a missing hourly report.

Though access to real-time data is restricted at the airlines' request, use of the site has continued to increase. In a recent month, the site was accessed by more than 80 sites, such as airlines, United States and foreign forecast offices, and research institutions. These sites requested more than 2,200 data loads, and looked at more than 4,600 soundings.

Interactive Soundings Website (http://www-frd.fsl.noaa.gov/mab/soundings/java/) – This Website was upgraded, and interactively displays past and forecasted soundings from a variety of sources. Data as high as 10 hPa may be displayed, and the sounding plots can be zoomed to provide a detailed look at smaller altitude ranges. Soundings from analyses and forecasts are available for the past 36 hours, and for up to 36 hours into the future.

Radiosonde data from the past two years may also be displayed, and so can current profiler data and ACARS data ( for authorized users).

Data from multiple sources, times, and stations may be overlaid. To facilitate forecasting of severe weather events, thermodynamic stability indices are generated for all soundings that include humidity information. Also, interactive parcel trajectories may be generated which provide information about Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) for any expected maximum temperature and humidity. This page is becoming increasingly popular, with more than 25,000 accesses from 249 sites in January. The easily adaptable Java code that runs this site has been requested by several organizations, and has been released to them under FSL's new open-source software license/disclaimer.

National Real-Time Precipitation Website (http://precip.fsl.noaa.gov/hourly_precip.html) – Development and upgrades continue on this Website, which displays data that are provided by the National Centers for Environmental Prediction (NCEP). Data are displayed on a national map that optionally displays rivers and county boundaries. Data under the cursor are revealed as the cursor is moved across the map, and daily time-series of the data are available with a click of the mouse. The user can zoom and roam on the map to observe detailed local structure of precipitation events. Currently, several years of precipitation observations are available at the Website. Simplified scripts were written to reconstruct the display datastreams for days when data delivery is delayed. The updating of metadatasets necessary for accurate plotting of precipitation observations was automated, with help from the Facility Division.

National Mesonet Website – Using Java, a national mesonet Website was developed to interactively display observations from six mesonets and the METAR network. More than 3,000 stations are typically reporting from an area that covers Mexico, Canada, and the United States. At the request of the mesonet operators, this site is currently restricted. The site displays weather data and quality control information from FSL's Meteorological Assimilation Data Ingest System (MADIS).

The Java code that supports the geographic mapping on this site was upgraded from FSL legacy code to include the entire world, and uses the Lambert conformal conic projection in every case except when the entire world is displayed, when it uses a cylindrical equidistant projection. The maps are fully zoomable, including across the dateline and over the poles, and rivers are optionally shown in the United States, Mexico, and Canada. Background map data are compressed for faster downloading. The code is compliant with Java version 1.1; Java version 1.2 was not chosen because it is not yet supported by most browsers. The code has also been modularized for easier use in other display applications.

Quasi-Nonhydrostatic Model Website (http://www-frd.fsl.noaa.gov/fsl/qnh/) – QNH model results are available on the Web. Plans are to store up to two years of output from this model on the Web, thereby creating an online equivalent of the traditional weather map room. The user can select a desired date and a run type to bring up an extensive menu of available products for that day. Products consist of static maps as well as time-lapse loops. This page was upgraded to include forecasts for every 3 hours out to 36 hours.

Publications Website (http://www.fsl.noaa.gov/publications/index.html) – FSL publications are now supported by a maintained database and a search engine. This Website, run by perl cgi scripts, allows searching for FSL's publications based on specific criteria. Data entry functions for the database are performed over the Web via a restricted site, and several enhancements have been made to streamline the entry of new publications.

GAINS – The GAINS PIII balloon will be demonstrated in a 48-hour flight, and laboratory tests of an experimental pump will be completed. Software will be developed to verify trajectory forecasts. Balloon trajectory software based on RUC-2 winds will be completed.

Forecasting of Clear-Air Turbulence – Investigations will continue of the meteorological conditions under which the DTF algorithms did not predict turbulence. A field program in 2001 will be conducted using research aircraft, sounding data, and additional operational weather data to characterize the atmosphere around jets and fronts that produce clear-air turbulence.

Research Quality Datasets – Additional software corrections will likely be added as further error reports are received. When these changes reach a substantial amount, a revision description will be posted to the CD-ROM Website. At that time, more discussions will be initiated with NCDC to locate a mirror website there to provide access to the HPD utilities when either Website is disabled. Depending on available resources (possibly an ESDIM proposal during 2001), an updated CD with recent observations may be produced, and additional options for data display may be developed and incorporated into the CD software. The HPD CD-ROM Website will link a page with software revisions and corrections to the existing user Website to present information about changes and fixes in the access and display software. In addition, revisions to the Website will be made to 1) indicate the timing of release of a hoped-for updated CD with observations after July 1998 and 2) add display capabilities for observations in Hawaii, Alaska, and Pacific and Caribbean Islands.

Radiosonde Data Archive – Complete radiosonde data processing for 2000 and incorporate these data into the North American Radiosonde Data archives.

PV Streamers – The concept of a dynamical linkage between PV streamers and heavy-rain-producing MCCs with high-resolution numerical simulations will be tested. Staff will continue diagnostic studies of mesoscale convective systems that form in association with PV streamers.

FSL Websites

GAINS Website – This site will be updated with recent experimental and field tests results.

National Hourly Precipitation Website – A page of software revisions and corrections will be linked to the existing user Website to present information about changes and fixes in the access and display software. In addition, revisions to the Website will be made to 1) indicate the timing of release of a hoped-for updated CD with observations after July 1998 and 2) add display capabilities for observations in Hawaii, Alaska, and the Pacific and Caribbean islands.

ACARS Website – The Java display will be enhanced to include a world map for displaying ACARS data over Europe and Asia. Impact studies will continue regarding the robustness of ACARS soundings during inclement weather.

National METAR Website – The translation of raw METAR reports will be improved, and user suggestions for general enhancements to the site will be incorporated.

Interactive Soundings Website – The color coding will be changed to support users with color-impaired vision, and user suggestions to enhance the site will be implemented.

National Satellite Image Looper Website – Additional satellite image channels will be implemented as they come online.