FSL in Review 2001 - 2002

Cover/Title Page

Organizational Chart

Office of the Director

Office of Administration
and Research

Information and
Technology Services

Forecast Research

Demonstration Division

Systems Development

Aviation Division

Modernization Division

International Division


Acronyms and Terms

Figures Listing

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Nita Fullerton

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FIR 2001 - 2002 DD MastHead
Margot H. Ackley, Chief
(Supervisory Physical Scientist)

Web Homepage: http://www.profiler.noaa.gov

Norman L. Abshire, Electrical Engineer, 303-497-6179
Leon A. Benjamin, Programmer Analyst, 303-497-6031
Michael M. Bowden, Engineering Technician, 303-497-3260
James L. Budler, Engineering Technician, 303-497-7258
James D. Bussard, Information Systems Specialist, 303-497-6581
Michael A. Carrithers, Electronics Technician, 303-497-4376
Robert L. Cinea, Data Technician, 303-497-6200
Michael C. Foy, Systems Analyst, 303-497-4618
David J. Glaze, Electrical Engineer, 303-497-6801
Daphne M. Grant, PHASE Student, 303-497-5627
Seth I. Gutman, Physical Scientist, 303-497-7031
Kirk L. Holub, Systems Analyst, 303-497-6642
Bobby R. Kelley, Computer Specialist, 303-497-5635
Brian A. Koonsvitsky, Logistics Specialist, 303-497-3095
Michael J. Pando, Information Systems Specialist, 303-497-6220
Brian R. Phillips, Senior Engineering Technician, 303-497-6990
Alan E. Pihlak, Computer Specialist, 303-497-6022
Susan R. Sahm, Computer Specialist, 303-497-6795
Michael K. Shanahan, Electrical Engineer, 303-497-6547
Jebb Q. Stewart, Programmer Analyst, 303-497-6832
Scott W. Stierle, Systems Analyst, 303-497-6334
Richard G. Strauch, Electrical Engineer, 303-497-6385
Douglas W. van de Kamp, Meteorologist, 303-497-6309
David W. Wheeler, Electronic Technician, 303-497-6553

(The above roster, current when document is published, includes government, cooperative agreement, and commercial affiliate staff.)

Address: NOAA Forecast Systems Laboratory – Mail Code: FS3
David Skaggs Research Center
325 Broadway
Boulder, Colorado 80305-3328


The Demonstration Division evaluates promising new atmospheric observing technologies developed by the NOAA Research Laboratories and other organizations and determines their value in the operational domain. Activities range from demonstrations of scientific and engineering innovations to the management of new systems and technologies. In support of NOAA's environmental assessment and prediction mission, the division uses new upper-air observing techniques to create and disseminate reliable assessments of weather, climate, space environment, and geodetic phenomena. The data and techniques developed and implemented by the division also support seasonal to interannual climate forecasts as well as the prediction and assessment of decadal to centennial climate change. Due to a largely unanticipated synergy between the requirements for atmospheric remote sensing and the more traditional applications of the Global Positioning System (GPS; i.e., positioning, navigation, and time transfer), the GPS-Met Observing Systems Branch within the Demonstration Division also promotes safe navigation by providing GPS and other observations to the National Geodetic Survey network of continuously operating reference stations (CORS), the U.S. Coast Guard, U.S. Department of Transportation (DOT), and other GPS users in the public and private sectors.

These activities are an investment in scientific research, the development of new technologies to improve current operations, and in NOAA's preparation for the future. The division has successfully demonstrated all major elements of three reliable, low-cost continuous upper-air observing systems – wind profilers, Radio Acoustic Sounding System (RASS) temperature profilers, and ground-based GPS-Met observing systems – that complement other operational and future ground- and space-based observing systems. New information network tools and techniques have been adapted to acquire and process Cooperative Agency Profilers (CAPs), GPS, and surface meteorological observations from NOAA, and other public/private organizations and international partnerships. This capability allows rapid expansion of observing system coverage at extremely low cost. The division has been heavily involved in transferring environmental expertise/technologies to improve NOAA's ability to serve its customers and forge stronger ties with its partners, especially NOAA's National Weather Service (NWS), DOT, and Department of Defense (DOD).

Currently the division is engaged in the following major projects:

  • Operation, maintenance, and enhancement of the 35-station NOAA Profiler Network (NPN), including three systems in Alaska. (Figure 35 shows both NPN and CAP sites).
  • Collection and distribution of wind and temperature data from CAPs.
  • Assessment of the RASS for temperature profiling.
  • Redeployment of a profiler to a site near Austin, Texas, in support of NWS operations and the growing mesonet in Texas.
  • Upgrade of the grounding and lightning protection systems for all profiler sites.
  • Development and deployment of a surface-based integrated precipitable water vapor (IPWV) monitoring system using the ground-based GPS-Met.
  • Planning and support activities for a national observing system which will include profilers and GPS-Met systems.

Figure 35 - NPN Locations

Figure 35. Location of all 35 NOAA Profiler Network sites and Cooperative Agency Profiler (CAP) sites that provide data via the Profiler Website.

The division comprises five branches organizationally; however, the branches work in a fully integrated team mode in supporting the overall objectives of the division.

Network Operations Branch – Monitors systems' health and data quality, and coordinates all field repair and maintenance activities.

Engineering and Field Support Branch – Provides high-level field repair, coordinates all network logistical support, and designs and deploys engineering system upgrades. The branch also redeploys any GPS or profiler systems as needed.

Software Development and Web Services Branch – Provides software support of existing systems, develops new software and database systems as needed, provides Web support of the division's extensive Web activities, and designs software to support a national deployment of profilers.

GPS-Met Observing Systems Branch – Supports development and deployment of the GPS-IPWV Demonstration Network, and provides software development and scientific support.

Facilities Management and Systems Administration Branch – Manages all computers, data communications, network, and computer facilities used by the staff and projects of the division.

Network Operations Branch
Douglas W. van de Kamp, Chief


The Network Operations Branch is responsible for all aspects of NOAA Profiler Network (NPN) operations and monitoring, including the coordination of logistics associated with operating a network of 35 radars and surface instruments (Figure 36). The original concept for an operational profiler network envisioned the Doppler radar profiler as part of an integrated upper-air remote sensing system capable of measuring winds, temperature, and humidity. The Demonstration Division's progress toward these goals include the addition of the Radio Acoustic Sounding Systems (RASS) for temperature profiling in the lower troposphere at 11 NPN sites, and GPS integrated precipitable water vapor (GPS-IPWV) systems for moisture measurements at all NPN sites. In addition to the 35 NPN sites, another 175 NOAA and other-agency sites are monitored for timely GPS positions and surface observations to produce real-time IPWV measurements. Additional wind and RASS data have been acquired from a growing number of independently operated profiler sites, now totalling about 60. These Cooperative Agency Profilers (CAPs) include many lower tropospheric boundary layer profiler sites plus a few higher power profilers similar to NPN sites. The data from these CAP sites are now being made available to the meteorological community in real time via the division's Webpage. Along with the four other branches within the division, this branch maintains and improves the NPN and BLP real-time data availability to the National Weather Service (NWS) and other worldwide users. The Network Operations Branch directly supports NOAA's mission of improving weather products and services by providing real-time comprehensive, high quality upper-air and surface observations to NWS forecasters and numerical weather prediction models.

Figure 36 - NPN Maps

Figure 36. The NOAA Profiler Network of 35 radars and surface instruments. The Alaska sites are shown at the left. Circles show location of NPN sites;
stars show location of NPN sites with RASS.


The availability of hourly NPN winds to the NWS remained high through 2001, averaging about 95%. A summary of the overall performance of the network for the past 11 years is presented in Figure 37. It is interesting to note the general pattern of decreased availability of hourly winds each year during the spring and summer months, compared to slightly higher availability during the fall and winter months. This pattern has been analyzed and is attributed to increased lightning activity and severe weather during the convective season (cause of more commercial power and communications problems), along with profiler hardware damage from nearby lightning strikes and site air conditioner failures during the summer. From this trend analysis, additional lightning suppression and communications equipment protection are being added to the profiler sites by the Demonstration Division's Engineering and Field Support Branch.

Figure 37 - NPN Data Return

Figure 37. NOAA Profiler Network 404-MHz profiler data availability from January 1991 – January 2002.

A significant portion of personnel time involves the day-to-day operations and monitoring tasks related to the hardware, communications, and meteorological data quality aspects of the NPN, resulting in the high data availability rates for the past few years. Other tasks include initial diagnosis of equipment failures, coordination of all field repairs and maintenance activities, and maintenace of logs of all significant faults that cause an outage of profiler data. Figure 38 shows the total number of hours of profiler data lost by fault type (such as component failures, scheduled downtime for maintenance, and power and air conditioner failures) for the past three fiscal years. The duration of each data outage is broken down into many different states, including how long it took to identify a failure, diagnose and evaluate the problem, wait for repair parts to be sent and received, restore commercial power or communications, and document when and how the fault was ultimately repaired. Figure 39 shows the distribution of these categories of downtime (normalized over the past five years). Analysis of all these states reveals important information regarding operation of the network, and was discussed in detail in last year's annual report. In addition to the data monitoring tasks, there are the financial aspects related to the continued operation of the NPN, including tracking land leases, communications, and commercial power bills for the profiler sites.

Figure 38 - NPN Data Loss

Figure 38. NOAA Profiler Network data lost by fault type for the
past three fiscal years.

Figure 39 - NPN Downtime

Figure 39. Distribution of NOAA Profiler Network downtime by categories (normalized over five years from 1997 – 2001).

Personnel in the Profiler Control Center (PCC) routinely monitor the NPN, currently noncommissioned by the NWS, only during normal working hours, 8:00 AM – 5:00 PM local time (27% of the total hours in a week). The remainder of the time, the profilers, dedicated communication lines, and Profiler Hub computer system operate unattended. The division has made significant improvements in its ability to remotely monitor activity within the NPN, Hub processing, and data communications via displays available on the Web and other tools. Activities that are now routinely monitored on the Web include information on profiler real-time status, data flow to the NWS Telecommunications Gateway (NWSTG), and ingest of profiler data into the Rapid Update Cycle (RUC) model at the NWS National Centers for Environmental Prediction (NCEP). These tools are used to remotely diagnose problems as they arise outside of normal work hours and have increased the availability of NPN data.

Examination of several years of data showed that a significant number of lost hours of data were attributed to the local main power breaker (200 amp) being tripped to the off position, usually caused by lightning related power surges. Simply resetting the breaker would restore operation, but still required a site visit. From this analysis, the Engineering and Field Support Branch designed and installed the capability to remotely reset the main breaker via a phone call to the site. This marked the first full year of the availablity of this capability. The Network Operations Branch routinely uses this method to restore profiler operations, as well as "power cycling" a site in an attempt to clear software "hangs" and other problems. The breaker reset capability was activated 108 times outside normal work hours to restore operations. It was successful 68 times (63% of the time), resulting in an additional 1,310 hours of profiler and GPS-IPWV data availability to profiler customers. These resets performed outside normal work hours alone increased data availability by 0.4%.

Staff investigated the time (in minutes) at which the hourly averaged NPN data became available following processing by the Profiler Hub, and when the data became available to NWS forecasters across the country and at NCEP. The results (Figure 40) show that the NPN data became available on the Hub at an average time of 14 minutes past the hour. The profiler data (plotted in red) are available as early as 10 minutes past the hour, given no communications problems with the incoming 6-minute data from all NPN sites. If there are any communications problems, the Hub waits for backup data to become available from the GOES link; this can delay data availability to as much as 17 minutes past the hour (when waiting for the latest GOES minute used in the NPN). The NWSTG automatically picks up these data from the Hub, and then queues them for transmission to all NWS offices and FSL. Branch staff monitored when the profiler data (plotted in green) were received back at FSL via the NWS NOAAPORT. Inherent communications delays were found to add a minimum of 4 minutes to the return receipt time of the data (evidenced by the first returned data becoming available at 14 minutes after the hour). The two unique spikes in each plot (hourly data available from the Hub at 11 and 16 minutes after the hour) are reproduced (and smoothed by independent communications delays) with a 4-minute delay in the NWS return receipt times (visible at 15 and 20 minutes after the hour). It is interesting to note the much longer delays of 30 to 60+ minutes at times. These delays (Figure 41) show the mean times of NPN data availability (in minutes past the hour) plotted as a function of the hour of the day. It can be seen that following completion of Hub processing (the nearly constant line at 14 minutes after the hour), NPN data are generally available to NWS offices within 6 to 7 minutes, except for two time periods each day. These two periods of significant delays, separated by 12 hours and centered around 0500 and 1700 UTC, are apparently due to the transmission of numerical model output data to all NWS offices, saturating the NWSTG. Since the NPN is currently a noncommissioned system, its data are given lower priority and queued for later transmission. After discussions with NWS, these delays have been reduced, but significant delays still exist at times.

Figure 40 - NPN Data Availability

Figure 40. Hourly NOAA Profiler Network data availability,
from 17 October 2000 – 19 January 2001.

Figure 41 - NPN Data Availability as Function of Time of Day

Figure 41. Hourly profiler data availability as a function of time of day,
from 17 October 2000 – 19 January 2001.

Two additional NPN sites (Neodesha, Kansas, and Jayton, Texas) were equipped with RASS for temperature profiling this past year. Eleven NPN sites now have RASS capabilities, typically providing measurements up to 2.5 – 4 km above the ground. In general, the velocity of the lower tropospheric wind limits the maximum height coverage of RASS by advecting the acoustic signal outside the radar beam. Each RASS-equipped site has four acoustic sources that are located inside the antenna field fence near the corners of the wind profiler antenna. Ongoing experiments are being conducted at Platteville, Colorado, and Purcell, Oklahoma, to investigate the impact of acoustic sources placed 35 – 140 m upwind of the profiler sites. Typical improvements of 500 – 1000 m in the RASS height coverage are observed when the 70 – 140 m upwind acoustic sources are activated. Prior to the latest RASS installations at Neodesha and Jayton, tests were conducted with the acoustic sources located (approximately 30 m from the profiler antenna) in the far corners of the profiler site's acre of land. No consistent improvements in RASS height coverage were observed; therefore the sources were placed in their normal configuration within the fence. Investigation continues concerning the optimum acoustic source location (distance upwind) and acoustic output power.

Low-power profilers that measure winds and temperature in the boundary layer to the lower troposphere (60 m to ~3 km above ground) have begun operating in greater numbers around North America in recent years. They primarily support air quality measurements and meteorological research programs, and typically operate independently or in small groups. Approximately 60 CAPs are currently operating and providing data to the Profiler Control Center in Boulder. The division is working in cooperation with other agencies to acquire BLP wind and temperature data that are processed into hourly and subhourly quality-controlled products, and are ultimately distributed along with products from the NPN. CAPs data are used for air quality monitoring and research, and have application to numerical weather prediction and subjective weather forecasting in support of NOAA's mission. The use of CAPs data from the Profiler Website was mentioned for the first time ever in an Area Forecast discussion from the NWS Wakefield, Virginia, office during a high wind event in December 2001.

A new data quality control algorithm was investigated and designed, and the specifications were sent to the Software Development and Web Services Branch for implementation. The algorithm detects and identifies RASS temperatures and radial velocity data contaminated by internal interference.

The division received 11 DEC (now Compaq) Alpha computers this past year that will be used to replace aging MicroVAXs at profiler sites. The Network Operations Branch participated in testing and validating the new systems. These systems could lend themselves to acquiring raw Doppler spectra, which will lead to improved data quality related to reduced ground clutter and internal interference, and enhance existing bird detection software.

The impact of ground clutter can be minimized using both software processing and hardware modifications. An expert in ground clutter suppression with NWS radars completed an initial analysis from a limited spectral dataset, and investigated the antenna structure height to fence geometry. A decision was made to increase the height of the security fence around the perimeter of the profiler site installed near Austin, Texas.


The Bird Contamination Check algorithm will be examined for possible additional improvements. The original algorithm analyzed only the hourly averaged north and east beams to detect the broader spectral widths caused by migrating birds. Recently the spectral width from the vertical beam was incorporated into the algorithm. The next significant improvement is likely to involve more sophisticated processing of the 6-minute moment data.

The division will continue to operate and maintain the 11 RASS-equipped profiler sites. Experiments will continue at Platteville and Purcell to investigate the optimum acoustic source locations (distance upwind) and acoustic output power. Improvements are expected in the quality control of RASS data, primarily during periods of internal interference, and in the presentation (i.e., contouring specific temperatures) of RASS data on the Profiler Webpage.

The CAP Hub will continue to be operated and used to acquire additional tropospheric profiler data from targets of opportunity, provide quality control for these data, and distribute that data to users via the Web and the NWSTG. Support will be provided to the Northeast Temperature and Air Quality Forecasting Pilot Program. Work is underway to acquire CAP data from a newly installed 25-station network operated by the Japanese Meteorological Agency.

The branch will support all aspects of planning, installation, activation, and evaluation of two relocated NPN profilers. The original 404-MHz profiler located near Platteville, Colorado, will be disassembled, transported, and reassembled at a site near Austin, Texas, in cooperation with the NWS Southern Region and the Lower Colorado River Authority in Texas. The 404-MHz profiler located at the Vandenberg Air Force Base in California was modified several years ago to operate at the official operational profiler frequency of 449 MHz, and was acquired last year for installation at the Platteville site to replace the original 404-MHz profiler.

Meteorological training for NWS forecasters in Alaska will be conducted, and will include theory of operation, use of profiler data, quality control issues, etc. Also, the possibility of developing an NWS COMET teletraining module related to wind profilers will be investigated.

Continued collaboration with others in the division to support the operations and maintenance of the NPN will help to maintain consistently high data availability statistics. This ultimately supports NOAA's mission of improving weather products and services, resulting in reduced loss of life and property damage from weather related events.

Return to Top of Demonstration Division Section

Engineering and Field Support Branch
Michael K. Shanahan, Chief


The primary focus of the Engineering and Field Support Branch is to carry out the operation, maintenance, and improvement of the NOAA Profiler Network (NPN). Through collaboration with the Profiler Control Center (PCC) at FSL, the 35-site network is monitored to assure data quality and reliability. Constant network upgrades, identification of network problems (using remote diagnostics analysis), and prompt corrective actions result in increased data availability.

In accordance with network maintenance agreements, the National Weather Service (NWS) Electronics Technicians do most of the preventive and remedial maintenance. The PCC uses the remote diagnostics capabilities to recognize failed components, order Line Replaceable Units (LRUs), and coordinate with the NWS electronics technicians regarding field repairs. More complex problems are handled by a team of specialized engineer/technicians, called Rangers, who are experienced in the design and operation of the profiler systems. Based in Boulder, the Rangers can be mobilized to the field on short notice to repair the profilers.


Alaska Profiler Network – Experiments were performed to find a solution to the ground clutter problems affecting the profiler at Central, Alaska. A temporary clutter fence was erected, and then extended 4 feet vertically. This provided a small but noticeable reduction in the clutter, and data quality improved slightly. (Figure 42 shows data availability from January 2000 – March 2002 at the 449-MHz Alaska Profiler Network.) A more permanent fence will need to be constructed at the site to withstand the snow loading and wind forces.

Figure 42 - Alaska Profiler Data Availability

Figure 42. Data availability from January 2000 – March 2002 at the 449-MHz profiler network in Alaska.

The 449-MHz power amplifier and antenna documentation and drawings were distributed to the Alaska NWS offices. All the spare parts to support the 449-MHz profiler network in Alaska were delivered and stocked at the National Logistics and Support Center in Kansas City, Missouri. With a new 449-MHz test bed, both 404-MHz and 449-MHZ profiler equipment can be tested and repaired on site.

Other NPN Sites – Profiler sites at Neodesha, Kansas, and Jayton, Texas, were equipped with Radio Acoustic Sounding Systems (RASS), bringing 11 of the 35 profiler sites configured with RASS.

The Vandenberg Air Force Base 449-MHz profiler (Figure 43) was moved to Platteville, Colorado, for installation in 2002. It will be used to test the functional requirements for a national network.

Figure 43 - 449 MHz Platteville, CO Profiler

Figure 43. Profiler shelter arriving at Platteville, Colorado, from Vandenberg AFB. This site will be used as a test bed for a national 449-MHz profiler network.

The Engineering and Field Support Branch designed a new digital surface meteorological instrument, the Profiler Surface Observing System II (PSOS II) to replace the current PSOS and GSOS (GPS Surface Observing System) instruments. Featuring a 10-meter mast with an anemometer and a rain gauge, the PSOS II is capable of measuring surface air temperature, relative humidity, precipitation, barometric pressure and wind speed and direction. The Rangers helped install 17 GSOS units.

Implementation of a newly designed grounding and lightning protection plan will continue, and all profiler sites will be tested and upgraded to meet the design specifications. Additional lightning and surge protection will be installed at the sites to safeguard the sensitive communications from damage.

The 404-MHz RF drivers were reconfigured to eliminate the dependence on obsolete components. Eleven new data processors were accepted, and will boost the current number of spare data processors.


A 404-MHz profiler complete with RASS, PSOS II, and GPS will be installed in the Austin, Texas, area in support of the NWS Southern Region and the growing Texas Mesonet. The Platteville, Colorado, profiler will be moved to Austin, and the 449-MHz profiler from Vandenberg AFB will resume operation at the Platteville location.

The grounding at wind profiler sites will be tested and modified from the current configuration to meet new design specifications. A uniform and organized grounding scheme for current and future electronics will be provided, and transient voltage and surge protection for all RS-232 communications will be added.

An all-digital surface meteorological sensor package (PSOS II) will be installed to replace the GSOS units currently operating at some profiler sites. This will be the first step toward providing uniformity among the 35 profiler sites and adding more surface meteorological data.

More experiments will be conducted to help reduce the amount of clutter that affects certain profiler sites in Alaska and the central U.S. Training will be provided to the Electronic Technicians in the Alaska region.

Return to Top of Demonstration Division Section

Software Development and Web Services Branch
Alan E. Pihlak, Chief


The Software Development and Web Services Branch is responsible for providing software support for existing systems, developing new software and database systems as needed, providing Web support for the division's extensive Web activities, and designing software to support a national deployment of profilers. A current priority involves improving the NPN Website, http://profiler.noaa.gov, so that it is the first place to go for wind profiler data. Another focus is improvement of the timeliness of profiler data delivery and distribution, through work on existing software systems and development of new software. The Profiler Website provides historical archives of wind, temperature, and other profiler information beneficial to researchers for forecasting and modeling both long-term and short-term climate change. (Figure 44 shows a sequence of screen shots from the main NPN Website of the installation of the profiler at the Ledbetter, Texas, site.)

Figure 44 - Ledbetter, TX Profiler Site - 1

Figure 44 - Ledbetter, TX Profiler Site - 2

Figure 44 - Ledbetter, TX Profiler Site - 3

Figure 44 - Ledbetter, TX Profiler Site - 4

Figure 44. Photos showing some phases during construction of the profiler at Ledbetter, Texas. a) top figure, antenna support in progress, b) second from top, radar weld finished, c) third from top, antenna and RASS (crown-like structures) in place and fence being installed, and d) bottom, completed profiler. The NPN Website http://profiler.noaa.gov shows every sequence of construction at this profiler site.


During the last year the NPN Website was completely "overhauled," with improvements to the look and feel of the pages and in compliance with Section 508 guidelines. The Linux operating system and new hardware were acquired to improve the service level and to meet future capacity predictions. Web software was ported from legacy systems to these new systems and upgraded. Data from all profilers operated by the NPN as well as profilers operated by cooperative agencies were made available to the public via the Profiler Webpages. Division Web servers provided access to an average of 126 pages per day.

Significant progress was made on development of a software "toolkit" (using the Java language) consisting of low-level, reusable, independent software building blocks that can be assembled quickly into larger systems. Many of these components have been used in completing the first phase of the project to improve delivery of data to the NWS and NCEP. These data are now arriving an average of 6 minutes faster each hour than before, when data would occasionally arrive too late to be used in the NCEP numerical weather models. This was accomplished by changing the format of the data sent to NWS from conglomerate to individual per-station messages. GPS precipitable water vapor measurements are also being delivered to the NWS twice each hour.

Significant progress progress has been achieved in development of the Wind Profiler Processing Platform. The standard hardware and software configuration of these systems was determined. Software central to the platform was developed and is in use in the production environment.

The number of Boundary layer profilers (BLPs) that measure up to 5 kilometers of the lower atmosphere is increasing each year. For example, at the beginning of 2001 there were about 12 BLPs processed, and about 40 at the end of the year.


The division Website should have a minimum of one year's data from NPN and BLP profilers online and available for downloading or viewing during 2002.

The first field-operational Wind Profiler Processing Platform (WPPP) prototype will be installed at a local profiler. It will support a new high-data-rate GOES transmitter and emulate the old GOES transmitter to the profiler. It will provide a Web-based Portable Maintenance Terminal (PMT) interface for local or remote operation of the profiler. The SARSAT (Search and Rescue Satellite-Aided Tracking System) schedule delivery, verification, and maintenance will be supported. Hourly quality-controlled winds will be processed on the WPPP and distributed directly to the local WFO Local Data Acquisiition and Dissemination (LDAD) system, and indirectly to other consumers. Another task that will be finalized is development of new, reusable graphics software for displaying winds, temperatures, and moments from either the Web or local or remote datasets.

Return to Top of Demonstration Division Section

GPS-Met Observing Systems Branch
Seth I. Gutman, Chief


The GPS-Met Observing Systems Branch was formed in response to the need for improved moisture observations to support weather forecasting, climate monitoring, and research within NOAA. The activities of the branch primarily support NOAA's environmental assessment and prediction mission. It creates and disseminates reliable assessments of weather, climate, the space environment and geodetic phenomena using a new upper-air observing system technique in support of advance short-term warning and forecast services. The data and techniques developed and implemented by the branch also support seasonal to interannual climate forecasts as well as the prediction and assessment of decadal to centennial climate change. Due to a largely unanticipated synergy between the requirements for atmospheric remote sensing and the more traditional applications of the Global Positioning System (i.e., positioning, navigation, and time transfer), the branch's activities also promote safe navigation by providing GPS and other observations to the National Geodetic Survey (NGS) Continuously Operating Reference Station (CORS) network, the U.S. Coast Guard (USCG), U.S. Department of Transportation (DOT), and other GPS users in the public and private sectors.

The primary objectives of the GPS-Met Observing Systems Branch are to define and demonstrate the major aspects of an operational ground-based Global Positioning System (GPS) integrated precipitable water vapor (IPWV) monitoring system, facilitate assessments of the impact of GPS meteorological data on weather forecasts, assist in the transition of GPS-Met data acquisition and data processing techniques to operational use, and encourage the use of GPS in atmospheric research and other applications. The work utilizes the resources and infrastructure established to operate and maintain the NOAA Profiler Network (NPN) in achieving these objectives at low cost and risk. The branch collaborates with other FSL divisions (especially the Forecast Research Division, Aviation Division, International Division, Systems Development Division, and the Director's Office which includes the Information and Technology Services group) to achieve objectives of mutual interest and benefit the laboratory, its customers, partners, and stakeholders.

This work represents an investment in scientific research, the development of new technologies to improve current operations, and assistance in helping NOAA prepare for the future. The branch has successfully demonstrated all major elements of a reliable, low-cost, continuous upper-air observing system that complements other operational and future ground- and space-based observing systems. New information network tools and techniques have been adapted to acquire and process GPS and surface meteorological data from NOAA and other public private and international partnerships. This capability has permitted rapid expansion of GPS-Met coverage at extremely low cost. The branch has been heavily involved in developing and implementing environmental expertise and technologies to improve NOAA's ability to serve its customers and forge stronger ties with its partners, especially the National Weather Service (NWS), Department of Transportation (DOT), and Department of Defense (DOD).


The development and implementation of real-time data processing techniques last year is a hard act to follow. Seen in context, it formed the basis of this and all future years' operational GPS-Met activities. In 2001, the branch concentrated on expanding the GPS-Met demonstration network, improving data quality and availability to forecasters and modelers, enhancing the display of data and products, and supporting scientific research. Continued support was also provided for ongoing assessment of the impact that GPS-Met data has on weather forecast accuracy.

Expansion of the GPS-Met Demonstration Network

The addition of 22 sites to the GPS-Met Demonstration Network brought the size of the network to 76 stations, an increase of about 36% (Figure 45). The main reason for this growth during 2001 was the implementation of an agreement with the DOT that permits FSL to acquire GPS Surface Observing System (GSOS) sensor packages from the NWS National Data Buoy Center (NDBC) and install them at all DOT NDGPS sites throughout the United States. Seventeen NDGPS sites received GSOS packages last year, bringing the total number of NDGPS sites in the demonstration network to 21. When the DOT project started in 1997, the first NDGPS site to be built was located at Appleton, Washington (Figure 46). At the lower right corner of the picture is Mt. Hood in the Cascade Range. (One of the benefits of working on the GPS-Met project is being able to visit sites like this.)

Figure 45 - GPS-Met Network Growth

Figure 45. A chart showing 8 years of the growth of the GPS-Met Demonstration Network. The addition of 22 sites last year brought the size of the network
to 76 stations, an increase of about 36%.

Figure 46 - DoT NDGPS Site

Figure 46. Photo of the Department of Transportation NDGPS site in Appleton, Washington. Mt. Hood is seen on the right side.

In addition to the 17 NDGPS sites, 5 other GPS-Met sites were added to the network:

  • The NPN site near Neodesha, Kansas, was moved and reestablished.
  • The CORS site at the U.S. Naval Observatory (USNO) in Washington, D.C., which will also be used to improve USNO time transfer.
  • A NASA site on the Chesapeake Light Ocean Platform, Virginia, which will also be used to calibrate and validate Advanced Infrared Sounder (AIRS) data from the Aqua (EOS-PM) Spacecraft in 2002.
  • A tide monitoring site belonging to NGS at Bar Harbor, Maine.
  • A DGPS site in the City of Grand Junction, Colorado, belonging to the Mesa County Colorado DOT for surveying, 911 response, and infrastructure support. This site is the first nonfederal government site incorporated into the GPS-Met network, and paves the way for expanded cooperation with state and local government agencies in the future.

In 2001, FSL signed an interagency agreement with USCG and U.S. Army Corps of Engineers (USACE) that allows FSL to install GSOS packages at up to 55 maritime Differential GPS (DGPS) sites throughout the U.S. and its Territories. This agreement sets the stage for a substantial increase next year in the number of sites in the Mississippi and Ohio River Valleys, and along the Great Lakes.

Improving Data Availability and Quality

The branch collaborated with NGS and implemented a 30-minute data acquisition cycle for most of the CORS sites in the network. GPS and surface meteorological data were formally acquired at a variety of intervals ranging from 30 minutes at NPN sites to hourly at DGPS and some NGS sites, to daily at other NGS sites. Under the current scheme, data are acquired at two minutes and 32 minutes after the hour, reducing the latency of GPS-Met data and products to modelers and forecasters.

The branch developed a scalable distributed processing system using fast and inexpensive personal computer workstations running the Linux operating system. The basic architecture was validated this year, and some minor improvements were implemented to improve performance. In general, processor speed continued to increase in 2001 as prices fell, resulting in a significant improvement in network performance, throughput and cost effectiveness.

The entire Demonstration Division is cooperating with the NWS Telecommunications Gateway and the National Centers for Environmental Prediction (NCEP) to make GPS-Met and boundary layer profiler (BLP) data available to models and forecasters in real time. This work just began late last year, and much progress is expected in the coming year.

GPS-Met has three basic quality issues: orbit accuracy, zenith tropospheric delay (ZTD) estimation accuracy, and surface data accuracy. Orbit accuracy is determined by comparing calculated or predicted GPS satellite orbits with International Geodetic Service (IGS) final orbits. The GPS-Met project currently uses 2-hour predictions derived from Scripps Orbit and Permanent Array Center (SOPAC) hourly orbits. SOPAC produces these orbits with 1-hour latency, and provides the orbital parameters to the project for use in real-time data processing. SOPAC hourly orbit predictions have a mean error of less than 20 cm at the 2 sigma level with respect to the IGS final orbits. However, since the orbits are calculated from data supplied to SOPAC by a subset of the IGS global tracking network, and problems sometimes occur acquiring or processing these observations, predictions longer than 2 hours with uncertain impact on ZTD estimation accuracy may have to be used. In general, orbit errors introduce a slow degradation of ZTD accuracy and are difficult to detect. The branch asked SOPAC to investigate techniques to perform on-the-fly quality control, at least to provide an orbit quality flag for use in data processing. Unfortunately, all techniques investigated proved to be unreliable, and so the branch has implemented two levels of qualitative protection. The first involves notification that hourly orbit delivery has stopped and the orbits are more than three hours old. The second involves comparing the RMS scatter in the ZTD estimates (commonly referred to as the ZTD Formal Error or FERR) of stations very far apart. It was found that FERR generally increases as orbit quality degrades, and that if the FERR of stations very far apart (and at widely spaced magnetic latitudes) are highly correlated, then a bad orbit is usually responsible.

On occasion, ZTD accuracy at a site can degrade dramatically in a short period of time. This can be caused by data gaps that are usually associated with equipment malfunctions or communications interruptions, and electromagnetic (EM) interference. Detecting the former is usually straightforward, and is accomplished with high reliability by automatic monitoring of the data acquisition/data processing cycle. Errors caused by the latter are much harder to detect, especially if the level of interference does not cause a complete loss of data continuity. In fact, the only long-term solution to EM interference may be to move the site or terminate the source of interference. In view of the growing importance of GPS in national defense, aircraft navigation, and public safety, the latter may be the preferable course of action, especially when the interference occurs near an airport or sensitive facility.

Degradation of surface data quality causes errors in the retrieval of the hydrostatic signal delay from surface pressure, or estimation of the wet signal delay mapping function used to scale the wet delay into its water vapor equivalent. The branch, in cooperation with the Systems Development Division, has implemented methods to continuously monitor surface met sensor data quality and take as-required remedial action using a tool called the Mesoscale Analysis and Prediction System (MAPS) Surface Analysis System or MSAS (see http://msas.noaa.gov/qcms.html).

Enhancing the Display of GPS-Met Data and Products

The branch initiated a redevelopment of its Web page, http://gpsmet.noaa.gov, to improve the utility and availability of GPS-Met data to operators, forecasters, and researchers. Improvements include a real-time data collection monitor, a virtual status board, a quick-look option that shows seven days of data and products from all sensors at a site, and an interactive browser that permits the user to retrieve historical data as an image or a text file.

Many forecasters looking at the GPS-Met data on the Web comment that it would be very useful to be able to view GPS data on meteorological workstations, especially AWIPS. Clearly it would be useful to have map-view displays of the GPS-Met data and products to assist in subjective forecasting and facilitate data fusion. The International Division agrees that FX-Net would be an ideal platform to prototype the look and feel of GPS-Met workstation displays and functionality, and will begin to investigate ways to accomplish this in 2002.

Supporting Scientific Research

The GPS-Met Observing Systems Branch participated in two major scientific experiments, and began planning for two major field experiments in 2002. As was done during the CALJET experiments in 1997 and 1998, the branch participated in the 2001 PACJET experiment led by the Environmental Technology Laboratory. GPS-Met data were acquired, processed, and analyzed as part of a study to improve short-term forecasts of land-falling Pacific winter storms on the U.S. West Coast. Results from CALJET and PACJET 2001 are now appearing in conference and journal articles, and the lessons learned are being applied to the 2002 field campaign, which will include an expanded network of GPS-Met sensors.

Support was also provided for an experiment conducted by the Aeronomy Laboratory to detect the presence of the hypothesized water Dimer, and describe its attributes and distribution in the free atmosphere. GPS water vapor observations taken along a line from Boulder to Sterling, Colorado, provided an important constraint on the data analysis. GPS-Met data comparisons at five sites along this line are presented in Figure 47.

Figure 47 - GPS-Met Data Comparisons

Figure 47. GPS-Met data comparisons of GPS water vapor observations taken along a line from Boulder to Sterling, Colorado, during an Aeronomy Laboratory summer 2001 experiment to detect the presence of the
hypothesized water Dimer.

Finally, the branch submitted a successful joint proposal to the NASA Jet Propulsion Laboratory with the National Environmental Satellite, Data, and Information Service (NESDIS) Office of Research and Applications. The project involves the use of data from the GPS-Met network to calibrate and validate observations from the Atmospheric Infrared Sounder (AIRS) aboard the Aqua (formally EOS-PM) spacecraft, expected to be launched in April 2002.

Ongoing Assessment of the Impact of GPS-Met Data on
Weather Forecast Accuracy

Evaluations of the impact of GPS-IPWV observations on weather forecast accuracy have been conducted since 1997 within the Forecast Research Division. Results from 2000 and 2001 show 3-hour relative humidity forecast improvement (Figure 48) achieved by assimilating GPS-Met data into the Rapid Update Cycle (RUC). The difference between the two experiments was the number of sites in the assessment: 56 in 2000, and 67 in 2001. It shows the improvement in 24-hour precipitation forecasts achieved by assimilating GPS-Met data into the RUC in 2000 and 2001. Improvement in forecast accuracy is defined in terms of the Equitable Threat Score, Probability of Detection, and Bias.

Figure 48 - 24-Hour Precipitation Forecasts

Figure 48. Graphs showing improvement in 24-hour precipitation forecasts achieved by assimilating GPS-Met data into the RUC in 2000 and 2001. Improvement in forecast accuracy is defined in terms of the
Equitable Threat Score, Probability of Detection, and Bias.


GSOS is expected to be installed at about six new NDGPS sites during early 2002. Capitalizing on the signed agreement with the USCG and USACE last year, plans are to also install approximately 22 GSOS at maritime DGPS sites along the West Coast, Great Lakes, and in the Mississippi and Ohio River Valleys.

The GPS-Met Observing Systems Branch is cooperating with NGS in a Center for Operational Oceanographic Products and Services (CO-OPS) program to use GPS to monitor the levels of the Great Lakes and its tributaries. Other participants include the Ohio State University, NOS Office of Ocean and Coastal Resource Management, NOS Office of the Coast Survey, OAR Great Lakes Environmental Research Laboratory, Canadian Hydrographic Service, and the National Resources Canada Geodetic Survey Division. This project may provide an additional 22 sites to the network.

The branch has been involved in an informal outreach activity to educate many federal, state, and local government entities about GPS-Met, convince them that it is in both their and NOAA's interest to jointly use these data, identify GPS sites belonging to these agencies, and persuade them to make their data available to FSL in near real time. Some of these efforts are progressing, but require a more formalized technical and programmatic outreach effort in order to reach completion. These goals are being accomplished through cooperation with the FSL Aviation Division. In concert with this activity, the branch will investigate ways of using only the tropospheric delays calculated at these sites, without the benefit of collocated surface meteorological sensors. GPS-Met processing at these sites will be tightly coupled to data provided by nearby (but not collocated) surface met sensors, and numerical models for quality control and bias corrections. To facilitate the incorporation and display of GPS-Met data on operational workstations, the branch will work with various FSL divisions to use FX-Net to prototype GPS-Met workstation displays and functionality.

The branch will participate in three major experiments next year: IHOP, the New England High Resolution Temperature and Air Quality Forecasting Pilot Program, and the Aqua AIRS CAL-Val. To increase the amount of GPS-Met data available to forecasters, modelers, and researchers, all available SuomiNet data from UCAR will be acquired, processed, added to data from the Demonstration Network, and made available in real time to the teams conducting these experiments.

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Facilities and Systems Administration Branch
Bobby R. Kelley, Chief


The objectives of the Facilities and Systems Administration Branch are to manage and support the Demonstration Division communications and computer requirements. Duties include performing systems operations, systems maintenance, systems administration, network administration, NOAA Profiler Network (NPN) telecommunications administration, and support of the Global Positioning System Integrated Precipitable Water Vapor (GPS-IPWV) demonstration project. (Figure 49 shows a screen from the GPS-Met Demonstration Network main Webpage.) These responsibilities continue to cover a broad range of computers and communications equipment.

Figure 49 - GPS-Met Webpage

Figure 49. A screen capture of the GPS-Met Demonstration Network
main Webpage, http://www.gpsmet.noaa.gov/jsp/index.jsp.


NPN processing continues to be accommodated on 13 micro-VAXs configured in two clusters, primary and backup. Meanwhile, a development environment of networked PCs running Linux has been implemented to facilitate ongoing development of the modernized NPN processing system. Other data processing and Webpage hosting are in the process of being moved from a Sun E3000 server to a PC-based server running the Linux operating system, and this transition will be completed during 2002. GPS-IPWV processing has been moved to a network of PCs running the Linux operating system. Eighteen PCs running Linux are used for GPS-IPWV data acquisition, processing, and distribution. The division's file and e-mail server has been transferred to a PC-based server running the Microsoft Windows 2000 advanced server, which provides connectivity to more than 30 PCs running Microsoft Windows 9x, NT 4, or 2000. An improved backup file system was implemented to ensure rapid recovery in the event of system failures. Backup communications for NPN data acquisition continues to be provided through an Intel 386-based PC running SCO Unix that is connected to a DOMSAT receiver. Work is ongoing to replace this system with a PC running the Linux operating system and the new DOMSAT data acquisition software.

Telecommunications responsibilities cover 38 NPN data circuits within the lower 48 states and in Alaska. Day-to-day work continues to include new component installations and systems configuration on the division network, network problem isolation and maintenance, system configuration modifications to meet division requirements, system problem isolation and maintenance, in-house telecommunications maintenance or coordination for contracted maintenance, peripheral installation and configuration, computer and network security, preventive maintenance, information technology purchasing, and routine file system backups. Another primary focus of the Facilities Management and Systems Administration Branch is computer and network security responsibilities: ensuring system and data integrity and maintaining dependable NPN and GPS-IPWV data acquisition, processing, and distribution. Full-time (24/7) operations coverage continues to be provided during normal workdays through the Profiler Control Center in Boulder, and via pager during nights, weekends, and federal holidays.

Since an uninterruptable power system (UPS) was installed in the computer room and connected to the building emergency generator two years ago, maintenance of electrical power for the NPN and GPS-IPWV processing systems during adverse conditions has become virtually worry-free. Maintaining necessary computer room air conditioning is the next task at hand, and work to alleviate this shortcoming will be accomplished in 2002 with the installation of a stand-alone computer room air conditioning unit.

The table below shows data acquisition, processing, and distribution statistics for the past two calendar years. Improvements that were made prior to and during 2000 were proven maintainable throughout 2001. Development of the modernized NPN processing system is targeted to meet and exceed these statistics.

Year 2000
Year 2001
Average Communications Systems Uptime 96.8% 96.5%
Average NPN Processing Systems Uptime 99.3% 99.6%
Average Data Delivery to NWS 94.4% 94.6%


Job one is ensuring continuous and dependable acquisition, processing, and distribution of NPN and GPS-IPWV data. Plans are to maintain current operations and ensure continued timely data delivery to all customers. Further development, testing, and implementation of the modernized NPN processing system will continue. Success continues to be realized with a low-cost, high-performance approach of using off-the-shelf PCs running the Linux operating system. A stand-alone air conditioning unit is being installed in the computer room to help ensure NPN and GPS-IPWV data availability under adverse conditions or situations that might result in downtime of the building cooling systems.

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