ObjectivesThe Meteorological Applications Branch performs diagnostic studies of weather related phenomena, including clear-air turbulence, winter snowstorms, downslope windstorms, atmospheric soundings, and mesoscale convective systems. The diagnostic tools that are developed are applicable to observed fields and model grid point data, and they utilize statistical methods, fundamental dynamical relationships, and derived parameters that relate to unobserved variables. These studies often result in products of value to forecasters and are transferred to the National Weather Service. Additionally, the research-quality datasets that are assembled to support the branch's activities are also shared with other NOAA laboratories and NWS research groups.
Forecasting Clear-Air Turbulence
Diagnostic Turbulence Forecasting Algorithms – Branch scientists continue research on algorithms for diagnosing atmospheric turbulence, a hazard to aviation. Some algorithms have been proposed for forecasting turbulence, including the traditional empirical algorithms (e.g., Ri, Ellrod Index, etc.) and those with better physics (e.g., the Diagnostic Turbulence Function series DTF3, DTF4, and DTF5) developed at FSL. In order to compare the performance of these algorithms, an Algorithm Development System (ADS) was designed to calibrate, compare, and verify several algorithms with the same turbulence observations (pilot reports, PIREPS), the same model output (RUC-2), and for the same time period. The ADS is a RUC-2 model output archive of the basic variables (pressure, temperature, winds, height, and explicit turbulence kinetic energy around each PIREP) in a 4x4 grid column (40 levels) format that allows for computation of the turbulence variable from any algorithm. Furthermore, each algorithm can be calibrated by changing its internal parameters to obtain the best performance in the probability of detection of yes- and no-turbulence. The ADS data archive covering 1 November 1997 to 30 June 1998 was implemented and used to calibrate, compare, and verify algorithms Ri, Ellrod Index, DTF3, DTF4, and DTF5. The main conclusion from the comparison was that all the algorithms showed the same performance despite the fact that DTF3, 4, and 5 are based on better physics when compared with Ri, Ellrod Index, and other empirical diagnostic algorithms. These and other results were presented at the American Meteorological Society Eighth Conference on Aviation, Range, and Aerospace Meteorology. The unexpected results could be attributed to factors such as coarse vertical and horizontal resolutions of the operational model, interactions of diffusion and turbulence formulations, inadequate verification techniques, ambiguities in the PIREPs, and simplifications in the physics of the turbulence algorithms. A plan has been submitted to the Federal Aviation Administration (FAA) to investigate each of these possible factors in order to better understand and improve the algorithms. Also, the DTF3, DTF4, and DTF5 algorithms have been made available for a long-term verification and comparison using the Real-Time Verification System (RTVS) at FSL. These algorithms were also provided to NCAR-RAP for inclusion in the Integrated Turbulence Forecasting Algorithm (ITFA).
Another task of branch staff is to improve and maintain the turbulence forecast product on the FSL Web page. This product consists of the eddy dissipation rate of turbulence generated with the algorithm DTF5 using 40-km RUC-2 output. Several Center Weather Service Unit (CWSU) forecasters at some of the main airports have found effective use of the turbulence forecast product. Improvements in the forecast product display have been made as a result of suggestions from these forecasters. A hypothesis is being checked out at FSL that the use of this product has contributed to the reduction of pilot reports of severe turbulence. This is possibly due to the fact that pilots can now use the algorithm to avoid regions of turbulence, along with the guidance provided by the forecaster. The FSL Web display of DTF5 is the first product to provide information about the possible turbulence intensity that aircraft could encounter.
Diagnostic algorithms for forecasting turbulence related to convection and turbulence from gravity wave breaking (GWB) were developed for use with output from the RUC-2 operational numerical model. These algorithms have been subjectively verified and will be made available to the RTVS for a long-term verification.
The explicit turbulence forecast product from RUC-2 has been subjectively verified using PIREPs. The explicit turbulence field is based on the Burk- Thompson level 3.0, second-order closure formulation (BT3.0), which is being verified with PIREPs in the RTVS. A turbulence forecast product was implemented on an FSL Website.
Prognostic Turbulence Forecasting – Turbulence forecasting has also been investigated with parameterizations running in numerical weather models. Several formulations (Mellor-Yamada, Burk-Thompson, TKE-epsilon) have been tested, with special emphasis on the 1.5-order closure formulation implemented in the SALSA model and the Advanced Regional Prediction System (ARPS). Two- and three-dimensional simulations with ARPS (a high-resolution, nonhydrostatic model developed at the University of Oklahoma) using initial conditions from severe windstorm and convective regimes have demonstrated that the simple 1.5-order closure formulation is able to describe turbulence from gravity wave breaking associated with windstorms, shear instabilities and convection-induced turbulence (CIT). These results demonstrate unequivocally that a single parameterization can be used to describe several sources of turbulence. As in the case of CIT forecasts, accuracy of the turbulence forecast depends on the initial conditions and model performance.
Northeast Colorado Front Range Windstorm Research
Another area of research involves better prediction of severe downslope windstorms and the mechanisms that produce them. During Fiscal Year 1998, this research became more interactive with ongoing model development work within the Forecast Research Division, and more inclusive of other mesoscale terrain-driven flow phenomena as it became apparent that RUC-2, which became operational at NCEP during the year, produces much more mountain-wave activity than either its predecessor, RUC-1, or the operational NCEP Eta model. During the RUC-2 field tests in December 1997 and January 1998, NWS field forecasters noted surprisingly large vertical velocity centers in the vicinity of three mountain ranges: the Rockies, the Appalachians, and the Sierra.
Investigation of this situation led to some important conclusions:
• The vertical motions produced by RUC-2 during and after the NWS field test are consistent with what is anticipated from the theory of vertically propagating mountain waves, though the amplitude may be larger than expected.
• RUC and Eta both produce vertically propagating mountain waves, but the structure of these waves differs systematically between the two models. In the Eta, waves are almost always of lower amplitude than those in RUC-2, and, contrary to theory, the Eta also usually fails to bring accelerated flow down the lee slopes of the terrain.
The first conclusion points to the need for more forecaster education regarding mountain waves (and gravity waves in general), and other mesoscale terrain effects that are appearing in models (gap flows, wakes, etc.). Most meteorologists lack complete understanding in this area, since it is rapidly developing and often not part of the standard meteorological curriculum for undergraduate and graduate students. To this end, a few lectures were given to students and forecasters on various aspects of this subject, with emphasis on the interpretation of operational models. Interestingly, in the last year or two, the third conclusion as it relates to the Eta model has been reached by a number of investigators independently. It points to a basic problem with the lower boundary condition associated with the "step-mountain" formulation in the Eta model; this particular aspect is being investigated at NCEP and elsewhere.
Other windstorm research involved continued gathering of windstorm verification data for future studies and interactions with some forecasters in the NWS Western Region regarding this problem. Also, in collaboration with the University of Oklahoma, a proposal was submitted to and consequently funded by the COMET Outreach Program to provide an opportunity for a graduate student to upgrade the forecast aid for Boulder and Fort Collins WNDFCST in long-term use at the Denver NWSFO (described in earlier annual reports). The wind verification data used for WNDFCSTcovers only three years; it is being extended at FSL using a number of data sources. Construction of this dataset involves combining and normalizing the reports from several individual sites with relatively short wind records to provide a long-term summary dataset that is reasonably representative of the windier parts of Boulder.
The Global Air-ocean IN-situ System (GAINS) Project
The Global Air-ocean IN-situ System (GAINS) is a program to develop the systems needed for an operational, global, in-situ observing system. The operational program, intended to begin in 2006, is conceived as a network of 400 high-tech balloons evenly distributed over the globe. Floating between 60,000 and 75,000 feet for one year with an initial payload of 500 pounds, these superpressure balloons are the vehicle for dropping sondes from the lower stratosphere to monitor Earth's meteorological, oceanic, and atmospheric chemistry environment. The observing capabilities of GAINS support the mission of NOAA to describe and predict change in the Earth's environment.
Four years ago FSL began work on a system designed to increase the number of operational soundings taken over ocean areas. The aim was to develop a "shear-directed" balloon to take soundings in the troposphere; the goal was to improve U.S. weather forecasts by the addition of these sounding data. As recent field experiments have shown, of critical importance to an accurate 24- to 48-hour forecast in the western United States (and a 5-day forecast for the East Coast) are meteorological soundings in the data-sparse Pacific Ocean. Results from recent field experiments by other organizations attest to the value of high-resolution, targeted sounding data taken in upper jets and frontal systems heading toward the West Coast. The tropospheric sounding balloon was meant to fill that need. The initial concept of a tropospheric balloon ran up against insurmountable difficulties related to engineering limitations and aviation safety issues. The balloon itself was the sounding device, taking meteorological data as it ascended and descended two times per day between 150 feet and 35,000 feet. However, pump requirements of high flow rates coupled with low weight and low power requirements ruled out almost all pumps on the market, and those that were available severely restricted possible soundings to one per day, at most. Moreover, the safety hazard these vertically ascending and descending balloons posed to general and commercial aviation, even over the less-traveled ocean regions, was too great a risk. However, there were viable aspects, and these have been recast as a stratospheric platform for environmental monitoring.
The GAINS balloons fill a void in the current global observing systems. Radiosondes and surface stations give detailed and accurate in-situ readings over land areas, while coverage of oceans and polar regions is quite poor. Remote sensing from satellites provides good coverage of the entire globe, but the nature of remote sensing often results in indirect measurement and averaging over large volumes with associated lack of detail. By providing high accuracy sondes distributed over the global atmosphere, GAINS could make existing satellite observations more useful by "anchoring" them to known values. More formally, a Kalman filter analysis shows that the best observations over extended areas come when very accurate point observations are combined with horizontal and vertical gradient information. The satellite and balloon-based systems would represent a truly complementary global observing system, where each can sense the environment in ways the other cannot, and whose combination offers much of the detailed knowledge of oceans and atmosphere needed for future science. While GAINS has much to offer NOAA's operational services that are oriented toward real-time use of data for shorter-term weather forecasts or longer-term climate assessments, the GAINS platform could have a significant role to play in developing and testing new environmental sensors, and in acquiring datasets difficult to collect otherwise.
During Fiscal Year 1998, an exhaustive set of tests was conducted (as shown in the table below) in preparation for long-term flights in the stratosphere. A majority of the experiments took place in the laboratory environment, where individual components and various configurations could be tested under simulated flight conditions. Indoor laboratory tests generally were performed in an environmental chamber to determine the capability of insulated subsystems to operate under extreme cold temperatures and very low pressures. The purpose of the outdoor laboratory tests was to determine performance of transmitters and receivers over distance and to confirm electromagnetic compatibility of the radios and their transmission/reception protocols. Two experimental flights on zero-pressure balloons were made in collaboration with the Physical Science Laboratory of New Mexico State University. These flights tested the capability of the GAINS instrument package to operate in the radiation environment of the lower stratosphere, as well as our ability to recover the payload (Figures 10 and 11). The GAINS package successfully weathered the 7-hour daytime and 12-hour night-to-daytime test, neither overheating during daylight hours, nor cooling below design-point temperatures of 0oC for the batteries and -20oC for the instruments on the overnight test. The final sequence of tests in Fiscal Year 1998, including a tethered test at the University of Colorado-Boulder East Campus (Figure 11), was preparatory to a short flight of the GAINS 16-foot prototype II balloon from Tillamook, Oregon, for testing termination on command and monitoring balloon performance on descent.
Figure 10. Balloon recovery is an integral part of GAINS operations. Here the Recovery Team inspects the GAINS package at the northeastern New Mexico landing site of the 12–13 May 1998 flight. The white crush pads easily took the impact, and no payload instruments were damaged in landing.
Figure 11. A tethered test of the 16-ft prototype II balloon. An upward pointing video camera is being tested to monitor balloon performance and transition at termination.
Balloon Drift Simulations for GAINS Using a Simple Shear-directed Steering Model Forecast System
In creating a balloon management strategy for the GAINS project, an initial set of numerical experiments has begun for developing automatic control algorithms. Preliminary balloon management studies have been aimed at defining the problem in a tractable form, and in developing low-level control algorithms (for single balloons) to be used by higher-order control structures (for balloon networks). The objective of the control algorithm is to maintain the balloon on a designated latitude circle by adjusting its altitude.
Year-long trajectories have been computed using the 1997 National Centers for Environmental Prediction (NCEP) reanalysis data to simulate the effects of stratospheric winds. Reanalysis data are available every 6 hours at 17 mandatory sounding levels on a global 2.5o latitude by 2.5o longitude grid. The 6-hour kinematic data are interpolated linearly to the particular temporal and spatial location of the balloon to simulate balloon drift. The release point for all balloon simulations is Tillamook, Oregon (45.42oN 123.813oW), and the integration time step to compute the balloon's trajectory is 0.1 hour.
If no corrections are made in flight levels, the balloon drifts uncontrollably over most of the Northern Hemisphere (Figure 12). Restoring a balloon to a preselected latitude is achieved by selecting an altitude that has favorable winds for driving the balloon back to the designated latitude. One method tested was the following. At each synoptic time (0000 and 1200 UTC), a correction in flight level is introduced instantaneously by selecting the maximum or minimum value of the meridional component of the wind which most quickly would restore the flight track to the desired latitudinal circle. This simple steering model is able to keep the balloon on track for most of the year except for a few deep circulations that the balloon encounters, which throw it well off course (Figure 13).
Figure 12. A simulated trajectory for one year for a balloon released from Tillamook, Oregon, on 1 January 1997 0000 UTC at 70 mb and allowed to drift at that level without any further controls.
Figure 13. As in Figure 12, but the flight level is changed every 12 hours at synoptic sounding times (0000 UTC and 1200 UTC) by selecting the level at which there is the fastest restoring meridional current to a desired drift latitude (30oN). Blue represents westerly tracks/winds and red represents easterly tracks/winds.
For the second method, a change in altitude can again be made at 0000 and 1200 UTC. However, the balloon trajectory for the next 12 hours is "forecast" for four flight levels (150, 100, 70 and 50 mb) assuming no change to the analyzed winds in the 12-hour period. The pressure level which takes the balloon closest to the specified latitudinal circle is the selected flight level. This algorithm (Figure 14) gives superior results compared to the other two plots. The best control of drift latitude is obtained near the equator (Figure 15). Control deteriorates for balloons approaching poleward latitudes because the effects of extratropical cyclones make it more difficult to keep the trajectory within a few degrees of the specified latitude.
Figure 14. As in Figure 13, but the flight level is changed every 12 hours at synoptic sounding times (0000 UTC and 1200 UTC) by selecting the level at which persistence forecast of 12 hours (stationary pattern of flow) generates a corresponding trajectory that approaches closest to the target latitude in 12 hours.
Figure 15. A series of balloon drift latitudes that make use of restoring 12- hour persistence trajectories for target latitudes of 10o, 20o, 30o, 40o, and 50o N as functions of the Julian day (1997).
Quasigeostrophic vertical motion is being used to evaluate and compare the performance of various numerical weather prediction (NWP) models. In general, the vertical motion fields from two different NWP models do not correlate very well. At initial times, the RUC-2 and Eta model omega fields may have no better correlation than 50% on each pressure level.
QG vertical motion (QG omega) computed from the adiabatic omega equation approximates the Rossby component of model vertical motion. NWP models such as 48-km Eta, Aviation, and RUC-2 are found to be in substantial agreement in QG omega at mid topospheric levels, but differ significantly in other components of omega. If the QG omega field is removed on each level as a principal component, the residual components have a no better than 25% correlation between the two models. In other words, there is a consensus in NWP models on what constitutes the Rossby component of vertical motion, but there is disagreement in defining vertical motion associated with the fast modes and convection. These latter components reflect the various ways that models characterize roughness, surface heating, and evaporation, and how they parameterize and resolve convection and gravity waves.
Research Quality Datasets
Hourly Precipitation Data on CD-ROM – During 1998, several tasks required prior to the production of Hourly Precipitation Dataset (HPD) CD-ROMs were completed. The first was the design and development of a local FSL Web page where CD-ROM software to access the data on CD-ROM and display it will be disseminated. Second, several prototype CDs produced at the National Climatic Data Center were carefully examined and subsequently revised. Third, a CD slipcover with accompanying information was designed and provided to NCDC (Figure 16). Improvements were also introduced to the Web browser-based Java display routine that will be provided to users to display data from the HPD. These included enhancements to the time-series display at individual stations, and the interactive utility to create precipitation totals for selectable time periods directly from the time-series display. Performance of the Java applet was also improved. The entire display package can be examined here.
Figure 16. CD slipcover, front and back, location at http://precip.fsl.noaa.gov/hpd/.
Data Quality and Other Characteristics of Real-time Hourly and Daily Precipitation – As part of an effort to evaluate real-time hourly gauge precipitation measurements for use in national-scale analyses, observations from the Hydrometeorological Automated Data System (HADS) were systematically compared with higher-quality retrospective hourly data from the Hourly Precipitation Dataset (HPD). For a data-rich region in the Ohio River Valley, a measure of analysis credibility (essentially the percentage difference, averaged across all gridpoints in the domain, between several pairs of analyses , where each analysis is created by randomly eliminating a few gauges in each grid area) shows that data quality is a critical issue in the value of analyzed precipitation fields. The possible complicating effect of differing gauge resolutions was addressed during a 20-year period when the sensitivity of gauges at HPD sites was changing from a hundredth to a tenth of an inch. As Figure 17 shows, the gauge resolution has little effect on the distribution of extreme values of precipitation. However, rainfall frequencies change dramatically when precipitation is observed in increments of 0.1 inch instead of 0.01 inch (Figure 18). Obviously, this effect must be considered when gauge networks are used to examine precipitation frequency. More details of this comparison are available on an FSL Website.
North American Radiosonde Database – In collaboration with NCDC, an update to the radiosonde data archive for North America has been completed. GTS and NCDC archive data are processed and merged into an archive at FSL. Enhancements to the archive include modifications to make this dataset and related software Y2K compliant, and reprocessing of data from 1994 through 1997 to include all data levels (previously we only took data up to 100 mb pressure). This reprocessing led to the creation of a fifth CD (1994–1997), to augment those data from the first four CDs (1946–1996). Software to access the data is available for DOS, VMS, and many UNIX operating systems, including HPUX, SUNOS, DEC/RISC, IBM/RISC and DEC/ALPHA. Users can access the data in either time-series or station-series sorts, and by station identifier (WMO or WBAN), or by geographic location. Data can be output in FSL, FAA604, or netCDF formats; online help and documentation are provided with the software.
Figure 17. The effect of gauge resolution on the distribution of extreme values of precipitation. Shown are percentiles (90th, 95th, and 99th) for the distributions of daily total precipitation between 1965 and 1986 at all hundredths- and tenths-measuring Hourly Precipitation Dataset (HPD) gauge sites in a data-rich region of the Ohio Valley.
Figure 18. The effect of gauge resolution on precipitation frequencies. Shown are percentages of hours in July with measured precipitation observed by hundredths-inch and tenths-inch measuring HPD gauges.
Hungary Extreme Precipitation Project
A three-year project (funded jointly by Hungary and the United States) to improve the forecasting of severe weather and extreme precipitation in Hungary will end in July 1999. During visits of staff from the Hungary Meteorological Service (HMS) to Boulder and FSL personnel to Budapest, several of the project objectives were accomplished. First, the utility of a real-time precipitation estimate called the Probable Maximum Precipitation (PMP) was assessed for three dangerous convective storms in Hungary during the summer of 1998. Second, satellite estimates (using the Griffith-Woodley satellite rain estimation technique) for these cases were produced and compared with gauge-measured precipitation totals. A novel application was the introduction of model-generated thermodynamic profiles into a procedure to adjust these estimates. Rainfall patterns were accurately depicted by the satellite rainfall fields, but questions regarding the magnitude of the rainfall and processing of satellite data require further investigation. Third, gauge measurements for summer 1997 were assembled for later use in studies of the diurnal pattern of precipitation and the overall distribution of 6-hourly rainfall in different geographical regions of Hungary. One goal of this last effort will be to determine if the diurnal pattern and rain rate distribution suggest a significant contribution by mesoscale convective systems.
The Parallelizing Preprocessor (PPP) is a text translation tool built to simplify the process of parallelizing Fortran codes targeted for massively parallel processor (MPP) systems. Directives, in the form of comments, are inserted into the sequential code and processed by PPP to create the parallel code. A directive-based approach was chosen for several reasons. Since directives take the form of a Fortran comment, the preprocessed version of the code produces the same results, with minimal impact to the original code. Ideally, development and changes to the code would be done on the preprocessed version, since it is still familiar to its author. Then when an MPP version is needed, the PPP is used to process the SMS directives to create the parallelized code. PPP directives have been designed to generate code to handle data decomposition, data movement, loop parallelization, local and global translation, reduction operations, and I/O operations. Upgrades to PPP have eliminated some directives while increasing the scope and translation capabilites of others. This parallelization tool is now being used to parallelize the Navy's COAMPS and the Taiwan Central Weather Bureau's GFS models, with efforts planned for FSL's RUC and QNH.
ACARS Website – A Website that displays weather data from automated sensors on commercial aircraft has been substantially upgraded by using the Java computer language. This site displays data from approximately 50,000 observations per day, acquired by sensors on approximately 700 aircraft operated by six airlines, and transmitted to FSL via the Aeronautical Radio, Inc. (ARINC) Communications Addressing and Reporting System (ACARS). Because the data are considered sensitive by the airline companies, access to real-time data is restricted to government and research organizations and participating airlines. However interactive demonstration versions of the displays are available here. By developing the ACARS displays as a Java applet, users need only access the FSL Web server once per time period investigated. Users can download the data to their computers to be displayed in a variety of different ways without further access to FSL. Thus, Internet delays are less problematic than they are when using the original (non-Java) Web displays, which require an access to FSL whenever the display is changed. Figure 19 shows data for a typical 24-hour period over the Continental United States, superimposed on an infrared satellite image. As the user moves the cursor across the map, the data under the cursor are shown. Also, the user may zoom any portion of the map by dragging the mouse across the desired region. In addition, the color bar on the right is interactive; by clicking and dragging with the mouse on one of the orange balls, the altitude range shown may be changed. Buttons above the display control additional display options. By clicking on any ascending or descending portion of a flight track, a sounding may be generated, such as that shown in Figure 20. This sounding is also interactive; data under the cursor is displayed as the cursor is moved over the sounding, and the sounding may be zoomed to reveal greater detail. The "load non-ACARS soundings" button allows users to load soundings from the MAPS/RUC-2 model output, and from RAOBs or wind profiler observations.
Because the Website provides the only way to access ACARS data from NWS field offices, it is the primary data source for an operational assessment of the use of ACARS in weather forecasting sponsored by NOAA's North American Upper Air Observing System Program. More than 15 NWS field offices are participating in this program, which is scheduled to run through the spring of 1999. Reports already submitted to this NAOS assessment already indicate that the site has been highly valuable in several forecasting situations.
In one case of note, forecasters at the Miami Center Weather Service Unit were called upon to help an airliner crossing the Atlantic that was facing a possible "fuel exhaustion" situation. Forecasters used the Website to identify an altitude with substantially lower headwinds. The airliner was directed to this new altitude and completed its flight without incident. A related Website, developed in 1998, allows users to download data in binary netCDF format to facilitate further analysis at their own organizations. Several sites are downloading these data on a daily (or hourly) basis.
Figure 19. Aircraft data for a typical 24-hour period (starting at 2200 UTC on 14 June 1999) over the continental United States, superimposed on an infrared satellite image.
Figure 20. An interactive sounding generated from ACARS data from a humidity- sensing aircraft descending into Oakland (OAK), California, touching down at 1046 UTC on 15 June 1999. Data at the altitude of the cursor shows pressure, altitude, bearing and range from the airport, observation time, dewpoint, temperature, and wind speed and direction.
Interactive Soundings Website – A Website was developed that interactively displays past and forecasted future soundings from a variety of sources. Data as high as 10 mb may be displayed, and the sounding plots can be zoomed to provide a detailed look at smaller altitude ranges. Soundings from the MAPS/RUC-2 analyses and forecasts are available for the past 36 hours, and for up to 36 hours into the future. RAOB data from the past two years may also be displayed. Data from multiple sources, times, and stations may be overlaid to facilitate comparison.
National Hourly Precipitation Website – We have continued to develop and upgrade a Website that displays hourly precipitation data that are provided by the National Centers for Environmental Prediction. Data are displayed on a national map, which 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 and thereby observe detailed local structure of precipitation events. The site can be accessed here (sample screen, Figure 21); it was awarded a "Top 5%" award from the Java Applet Rating Service, a recognition that it is among the most advanced and useful Web applications written in the Java computer language. In 1998, substantial improvements were accomplished in the speed with which this Website loads, particularly for those who are accessing the site via modem.
Figure 21. Sample screen from the FSL National Hourly Precipitation Website.
National Satellite Image Looper Websites – In a team effort with the other two branches in FRD, Websites that use the Java language to display satellite image loops have been upgraded and expanded. The original site received a "Top 5%" award from the Java Applet Rating Service, a recognition that it is among the most advanced and useful Web applications written in the Java computer language. These sites may be accessed here and here. These display time lapse images of satellite data in any of five spectral ranges. Images are available in both Lambert Conformal Conic Projection, a map projection that is commonly used in meteorology, and native satellite projection. Users receive automatically updated images, and can stay logged on for as long as they wish to maintain a constant watch on weather patterns as revealed by satellite. Users establish more than 250 sessions per day with our server, with each session lasting from a few minutes to as long as desired. The longest continuous access we have seen so far is 8 hours. Because the site is written in the Java language, most processing takes place on the users' computers, minimizing the load on the FSL Web servers. During 1998, the Java software that supports this display was adapted to several other functions, including producing timelapse loops of output from these FSL models: MAPS/RUC-2, LAPS, and QNH.
National METAR Website – Using the Java language, we have developed a Website that interactively displays observations from more than 2500 METAR sites in North America (Figure 22). Data are displayed on a national map, which optionally includes rivers and county boundaries. Moving the mouse over a METAR site reveals the temperature, dew point, wind and pressure at that site, as well as the time of the latest observation. Clicking on a site reveals the full raw METAR report in a separate window. The site may be accessed here. Although the development and maintenance of this site has not been a high priority, it is currently accessed more than 25 times per day by a variety of government and commercial users.
Figure 22. Screen from the FSL National METAR Website.
QNH Model Pages – QNH model results may be found on the web here. It is planned to store up to two years' worth of output from this model on the web, thereby making the on-line equivalent of a traditional weather map room. The user can select a desired date as well as a desired run-type, and this brings up an extensive menu of available products for that day. Products consist of static maps (sample in Figure 23) as well as time-lapse loops.
Figure 23. Screen from the Quasi-Nonhydrostatic Model Website showing forecast valid times for 10 June 1999.
Web-based Email Discussion Forums – Software from elsewhere was adapted to establish several Web-based discussion forums, for the MAPS/RUC-2 model, the WRF model, Turbulence and ACARS pages, among others. This year, the software was upgraded to allow users to post messages to the forums by sending email; it is no longer required to access the forums' Web pages to post messages.
Supporting Software – Two tools to support web efforts were developed during 1998. A menu-generator is used by both the MAPS and QNH Websites to facilitate changes to extensive product menus that appear on these sites. An on-line presentation generator has been used in both the MAB and LAPS branches to facilitate the development of overhead-transparency-like groups of web pages that can be used when giving presentations.
ACARS Quality Control System – A computer program to flag, and in some cases correct, weather data from automated sensors on commercial aircraft (ACARS) has been upgraded. The quality control system uses temporal and spatial consistency along each flight track, as well as altitude-adjusted climatological consistency, to discover errors. It also interpolates locations and times for high-resolution observations taken during ascent and descent, enabling these data to be used in numerical weather prediction model research and in weather forecasting. In 1998, the ACARS quality control system was upgraded to:
• accommodate a new format for eddy dissipation rate (turbulence) data,
• take advantage of the origin and destination airports in order to facilitate the generation of soundings in the Java-based ACARS display system, and
• improve processing for water vapor data.
In Fiscal Year 1999, the Meteorological Applications Branch will be involved in the following activities and studies.
Turbulence Parameterization and AIV Development
• Calibrate, compare, and verify (with PIREPs, vertical accelerometer, and in-situ eddy dissipation rate data) turbulence diagnostics (DTF3, DFT4, DTF5, Elrod Index, and Ri) using RUC-2 output during winter 1997–1998.
Front Range Windstorms
• Begin statistical analysis of upper air and verification data for purposes of deriving a more reliable, accurate version of WNDFCST for NWS application.
• Continue to investigate the performance of operational and experimental numerical weather prediction models (in collaboration with other groups within and outside FSL), particularly their ability to anticipate downslope windstorms or the conditions known to be favorable for them.
• Demonstrate the PIII instruments and balloon at 60,000 feet for 48 hours with over-the-horizon communications and sounding capabilities.
• make more obvious recent data and flight tracks that are likely to produce useful sounding data,
• provide more thermodynamic information on sounding plots,
• implement a world map for the Java-based display, and
• automatically ingest new data.
RTVS Website – The Aviation Division's Real-Time Verification System is a UNIX-based system that generates primarily graphical output showing model results statistically compared with verification data such as pilot reports. A Web-based interface will be developed for this system so that qualified users anywhere can use this analysis tool.
Interactive Soundings Website – This site will be upgraded to include data from profilers, RAOBS, and model soundings.
National METAR Website – This site will be upgraded to load more quickly, to be more robust (particularly on older browsers), and to display data more clearly.