INTRODUCTION

1.1 Purpose. The National Plan for Tropical Cyclone Research and Reconnaissance satisfies a provision of Public Law 102-567, the National Oceanic and Atmospheric Administration (NOAA) Authorization Act of 1992, Section 107, para c(2). The provision requires a follow-on management plan to provide for continued tropical cyclone surveillance and reconnaissance which will adequately protect the citizens of the coastal areas of the United States. The initial plan was sent to Congress in January 1994.

The program to collect operational and reconnaissance data, conduct research, and analyze data on tropical cyclones to assist forecast and warning programs and to increase the understanding of the causes and behavior of tropical cyclones is a longstanding one. Under the sponsorship of the Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM), the Working Group for Tropical Cyclone Research, an interagency group of tropical cyclone research scientists, managers, and operational meteorologists, prepared this document as a revision of the National Plan for Tropical Cyclone Research, FCM-P25-1992, which was published in July 1992. The purely operational aspects of the hurricane reconnaissance program are published annually in the National Hurricane Operations Plan (NHOP), which is often referenced in this plan. The 34th edition of the NHOP was published in May 1996. In addition, the OFCM hosts an annual Interdepartmental Hurricane Conference (IHC) which provides an excellent forum to exchange ideas, present proposals and developments on tropical cyclone research and reconnaissance, and coordinate changes to the overall program. In March 1996, the OFCM hosted the 50th meeting of the IHC.

1.2 Operational Forecast Agencies. The tropical cyclone warning service is an interdepartmental effort to provide the United States and designated international recipients with forecasts, warnings, and assessments concerning tropical and subtropical weather systems. The National Oceanic and Atmospheric Administration (NOAA) of the Department of Commerce (DOC) is responsible for providing forecasts and warnings for the Atlantic and for the eastern and central Pacific while the Department of Defense (DOD) provides the tropical cyclone forecasts for the remaining global tropical cyclone basins.

Tropical cyclone warning centers operated by U.S. agencies have some characteristics that set them apart from other national tropical cyclone warning agencies. The most significant of these are:

• In the Northern Hemisphere, they issue tropical cyclone forecasts out to 72 hours vice a maximum of 48 hours.

• Sustained winds are given as a 1-minute averaged wind vice a 10-minute averaged wind that is used by the remainder of the world.

• They all have access to several unique pieces of equipment such as the Weather Surveillance Radar-1988 Doppler (WSR-88D) and the Automated Tropical Cyclone Forecast System (ATCF).

• Several unique platforms are used for surveillance (the general monitoring of the entire area of responsibility to identify specific suspicious target areas) and reconnaissance (the process of gathering specific, highly accurate data over a relatively small target area). The U.S. is the only nation in the world that uses manned aircraft for hurricane reconnaissance.

1.2.1 NOAA's Tropical Prediction Center (TPC). NOAA's TPC has forecast and warning responsibility for the Atlantic Ocean and for the eastern Pacific east of longitude 140W. Under the new National Weather Service (NWS) Modernization Plan (Friday 1994; McPherson 1994), the former National Hurricane Center (NHC) is now incorporated into the Tropical Prediction Center, one of seven service-oriented centers and two central support activities that comprise the National Centers for Environmental Prediction (NCEP)--formerly the National Meteorological Center (NMC). To stimulate collaborative research activities, the Modernization Plan also calls for collocation of NWS operational offices with universities (Auciello and Lavoie 1992). Accordingly, TPC and the Miami Weather Service Forecast Office (WSFO) moved to the campus of Florida International University, Miami, Florida, in May 1995.

The TPC was structured in recognition of the fact that the mission of the former NHC was concerned with much more than tropical cyclones. The TPC is also a World Meteorological Organization (WMO) Regional Specialized Meteorological Center (RSMC). In this capacity, the TPC provides general weather guidance as well as specialized products for aviation and marine interests in the tropics. Because of the strong relationships between the TPC and the meteorological services of Mexico, the Caribbean, and Central American countries, the TPC will host, in the future, a tropical cyclone desk--a training and developmental function involving personnel from those services.

The TPC, with a staff of 41 people, consists of three major components:

• The Hurricane Specialist Unit, which comprises the NHC.

• The Technical Support Branch.

• The Tropical Analysis and Forecast Branch.

This staff is supplemented by a 4-person contract unit for satellite operations and on-site computer support; a 3-person Air Force Unit, known as the Chief, Aerial Reconnaissance Coordination, All Hurricanes (CARCAH), for reconnaissance coordination; two meteorologists from Caribbean area countries; a public affairs officer; and visiting scientists or foreign meteorologists assigned to TPC for periods of up to 1 year. Also transiently present are several scientists from the nearby Hurricane Research Division (HRD) of the Atlantic Oceanographic and Meteorological Laboratory (AOML). It is also expected that the TPC will interact with Florida International University (FIU) faculty and students. FIU recently established an International Hurricane Center that will focus on research associated with hurricane damage and mitigation. Some additional details are provided by Sheets (1995).

1.2.1.1 Hurricane Specialist Unit (National Hurricane Center). Hurricane forecasting is accomplished by the Hurricane Specialist Unit. During the "off" season, and as time permits during the season, the hurricane specialists prepare and write storm reports and seasonal articles, revise operational manuals, and respond to thousands of requests for information and assistance from public officials, other government agencies, the media, the private sector, and the general public. A considerable amount of time is spent in preparing and giving training courses for WMO and disaster preparedness officials. As time permits, the hurricane specialists also conduct applied research.

1.2.1.2 Technical Support Branch (TSB). TSB is responsible for technique development to improve forecaster efficiency and forecast accuracy. Activities include storm- surge studies, developing and maintaining various statistically based track and intensity prediction models, evaluating applications of atmospheric numerical models, conducting forecast verification studies, and data archiving. The branch is also responsible for internal TPC computer operations.

1.2.1.3 Tropical Analysis and Forecasting Branch (TAFB). The TAFB has the year-round responsibility for forecast, warning, and guidance products for large regions of the tropics. This responsibility includes aviation and marine forecasts and warnings, marine facsimile products, surface analyses, satellite interpretive and diagnostic products, and tropical weather discussions. TAFB meteorologists also support the NHC by analyzing GOES and METEOSAT satellite data and performing Dvorak technique classifications of tropical cyclones.

1.2.2 The Central Pacific Hurricane Center (CPHC). CPHC has the forecast and warning responsibility for the central North Pacific from 140W to the international date line. The CPHC is a component of the Weather Service Forecast Office (WSFO), Honolulu, Hawaii, which, in accordance with the goal of the National Weather Service Modernization Plan (Aucielo and Lavoie 1992) to collocate operational centers with universities, has moved to facilities at the University of Hawaii. The Meteorologist-In-Charge WSFO Honolulu is also the Director of the CPHC. The charter and direction for the CPHC are given in the National Hurricane Operations Plan (NHOP) (OFCM 1996).

1.2.2.1 CPHC Operations. The WSFO Honolulu has no authorized manpower for the specialized hurricane operations of the CPHC. Thus, the CPHC is activated only when a tropical cyclone crosses into the area between 140W and the international date line. Designated WSFO personnel who fill key positions at the CPHC are the Director, Deputy Director, Warning Coordination Meteorologist, Science and Operations Officers, and the hurricane forecaster. WSFO personnel must work increased shifts until the center is deactivated after tropical cyclone warnings are discontinued.

1.2.2.2 CPHC Support. Most outside support, such as model and techniques development and aerial reconnaissance, is provided through the same infrastructure that supports the TPC. Satellite reconnaissance is provided in-house by WSFO satellite specialists, and out-of-house by the Synoptic Analysis Branch of the National Environmental Satellite, Data, and Information Service (NESDIS), or from Department of Defense satellite analysis facilities (see section 2.2 for satellite and other technical capabilities). WSFO technicians maintain the equipment for the CPHC. During periods of outage, the TPC backs up the CPHC, and similarly, during outage periods at TPC, the CPHC provides backup for the eastern North Pacific.

1.2.2.3 International Forecasting Responsibilities. The Honolulu WSFO, in addition to its domestic forecasting and warning responsibilities, has the responsibility to issue international aviation and marine forecasts for the central North Pacific and marine forecasts for the central North Pacific and the South Pacific. It also prepares specially tailored analyses for American Samoa. The CPHC names all tropical cyclones that develop between 140W and the international date line using prescribed name lists given in OFCM (1996).

1.2.3 Joint Typhoon Warning Center (JTWC). The Joint Typhoon Warning Center (JTWC) was activated in May 1959 by the U.S. Commander-In-Chief, Pacific (USCINCPAC) as a joint Air Force/Navy tropical cyclone forecasting center that replaced more than six separate western North Pacific tropical cyclone warning centers. JTWC is collocated with and under the command of the Commanding Officer, Navy Pacific Meteorology and Oceanography Command Center (NAVPACMETOCCEN) West; the JTWC Director is an Air Force officer. JTWC is a full-time tropical cyclone warning center, manned by meteorologists from both the Air Force and Navy. JTWC gets its direction from the U. S. Commander in Chief, Pacific Instruction (USCINCPACINST) 3140.1 (latest of series), which is the DOD equivalent of the National Hurricane Operations Plan.

JTWC's charter is to:

• Continuously monitor all tropical weather activity in the its area of responsibility and issue appropriate advisories and alerts when tropical cyclone development is anticipated.

• Issue forecasts for all significant tropical cyclones.

• Determine requirements for tropical cyclone reconnaissance and assign responsibilities.

• Perform post-storm analysis of all significant tropical cyclones.

• Cooperate with the Naval Research Laboratory (NRL), Monterey, CA, on operational evaluation of models and aids, and on the development of new techniques.

It should be noted that the Base Realignment and Closure (BRAC) Commission has recommended that the NAVPACMETOCCEN West be deactivated, and that the JTWC move to Pearl Harbor, HI and become aligned under the NAVPACMETOCCEN. This move should not impact research support to JTWC.

As a result of the closure of the Naval Air Station at Agana, Guam, and the subsequent closure of the Naval Oceanography Command Detachment at Agana, the National Weather Service has established a Weather Forecast Office (WFO) at Tiyan, Guam. Effective June 1, 1996, the WFO Tiyan is the responsible office for issuing public typhoon advisories and statements (based on guidance provided by JTWC) for other U.S. government, territorial, and Micronesian government agencies.

1.2.3.1 JTWC Operations. JTWC is manned around-the-clock with an authorized staff that consists of a Director, a Deputy Director, and seven (4 Navy and 3 Air Force) tropical cyclone forecasters, although all seven are rarely trained and certified at one time. Eleven Navy and Air Force observers assist the forecasters as needed. The tour length at JTWC is from 15 months (unaccompanied) to two years (accompanied), but some forecasters and observers opt to stay longer.

JTWC is the world's largest tropical cyclone forecasting center in terms of its area of responsibility and the number of tropical cyclones for which it issues advisories. The forecast area of responsibility covers approximately 53 million square miles of the north and southwestern Pacific Ocean and the Indian Ocean. The area contains seven unique tropical cyclone basins. As tropical cyclone activity is winding down in one hemisphere, it is picking up in the other, and thus there is no "off season" for the JTWC.

Since the 1987 deactivation on the 54th Weather Reconnaissance Squadron in the western North Pacific, satellite imagery has become the primary reconnaissance tool. These data are provided from a multitude of sources:

• An Air Force contingent of 7 satellite analysts collocated with JTWC provides over 4000 tropical cyclone "fixes" and intensity estimates per year from geostationary and polar-orbiting satellite imagery, including analysis of microwave imagery data.

• Additional sites at Kadena Air Base (Okinawa, Japan) and Osan Air Base (Korea) provide several hundred fixes per year from polar-orbiting satellite imagery.

• Nearly 2000 satellite-based fixes and intensity estimates per year are received from the Air Force Global Weather Center (AFGWC), Offutt AFB, Nebraska, primarily in areas where JTWC does not have polar-orbiting satellite coverage. AFGWC is also the largest producer of microwave imagery information concerning tropical cyclone location and the distribution of gale-force winds.

• Fixes, based on polar-orbiting satellite data, are obtained from secondary sites; among them are Diego Garcia, Kwajalein Atoll, and U.S. aircraft carriers.

• Additional fix information is collected from other worldwide non-DOD satellite analysis centers, including NESDIS and foreign analysis centers, when available.

JTWC issues forecasts in regions in which many other international agencies are also issuing forecasts. This requires considerable interface with other international warning centers, especially when a tropical cyclone is impacting a heavily populated area common to the two centers. JTWC has the WMO responsibility for naming tropical cyclones in the western North Pacific. A more comprehensive description of JTWC operations is given in Guard et al. (1992). Additional operational aspects of JTWC are discussed in later sections of this document.

1.2.3.2 JTWC Support. The large JTWC mission, relatively small number of on-site personnel, and reliance on highly sophisticated computer models, require that JTWC receive considerable outside support. As discussed above, a great deal of the satellite support comes from external sources. Virtually all of JTWC's numerical model computer support comes from Fleet Numerical Meteorology and Oceanography Center (FNMOC)at Monterey, CA. Computer maintenance for JTWC automation is provided by on-site Navy technicians of NAVPACMETOCCEN West. Likewise, maintenance for Air Force automation is provided by on-site Air Force technicians who are augmented by Air Force technicians from Andersen Air Force Base, 20 miles to the north. This automation is discussed in more detail in Chapter 2. Research support is discussed below and in later chapters.

1.2.4 Central South Pacific. Warnings for U.S. interests in the central South Pacific are issued by NAVPACMETOCCEN Pearl Harbor, Hawaii. The unit is also the alternate Joint Typhoon Warning Center (AJTWC). Operational and research support are the same as that for JTWC.

1.3 Research Groups. In contrast to the three clearly defined operational centers, numerous groups are engaged in various forms of tropical cyclone research. Although 100 percent of groups conducting tropical cyclone research are not included, a good cross-section of current research focus in hurricanes and tropical meteorology is provided by an analysis of the 263 papers presented at the American Meteorological Society 21st Conference on Hurricanes and Tropical Meteorology, held in Miami in April, 1995 (AMS 1995).

Another index of current research is the 21 presentations given at the 49th Interdepartmental Hurricane Conference (IHC), held in Miami during February 1995 (OFCM 1995). However, most of the papers presented at the IHC were also given in one form or another at the AMS Conference held 2 months later. Therefore, a separate listing would not be fruitful. Some of the more significant research efforts reported at the IHC but not at the AMS Conference included work on the Special Sensor Microwave/Imager (SSM/I) gale wind radius estimates at Air Force Global Weather Center (C. Holliday, AFGWC); use of Air Force over-the-horizon radar to obtain hurricane wind speeds (T. M. Georges, NOAA/ETL); damage assessments from hurricanes for the Federal Emergency Management Agency (FEMA) (J. Bruno, Science Applications International Corporation); typhoon Fujiwhara interaction (LCDR Petzrick, JTWC); use of scatterometer data (C.S. Hsu and W.T. Liu, Jet Propulsion Laboratory); and quality assessment, integration, and use of reconnaissance data at NCEP (C. Nelson, NCEP).

Some additional domestic research on tropical cyclones was not reported at either of the two above cited conferences. This would include work at the University of Massachusetts on remote sensing of hurricane surface winds (HRD/AOML 1994), and proprietary work being done by the private sector.

1.3.1 Overview of AMS Papers. Tables 1.1, 1.2, and 1.3 address lead-author affiliations. Table 1.1 gives an overall lead-author affiliation breakdown of papers presented at the AMS Technical Conference and also shows the number of tropical cyclone papers sponsored or partially sponsored by the Office of Naval Research. Although many of the papers presented at the conference relate directly to tropical cyclone understanding and prediction, others were related more to general tropical meteorology. Many of the latter can have some indirect benefit in providing a better understanding of tropical cyclones. Most of the general tropical meteorology and tropical cyclone-related papers (57 percent) were presented by lead authors associated with domestic or foreign universities.

Almost all of the university tropical cyclone research is supported by government agencies such as the Office of Naval Research (ONR) or other DOD agencies, National Science Foundation (NSF), NOAA, National Aeronautics and Space Administration (NASA), etc. Approximately 45 percent of all (U.S. and foreign) tropical cyclone-related papers were funded by ONR. Research by the foreign universities, notably, the University of Munich (7 papers), Monash University and a few other Australian universities (7 papers), and the City University of Hong Kong (4 papers) is also at least partially supported by ONR grants as well as local sources. Since most of the other agencies listed in Table 1.1 are government agencies, most of current tropical cyclone research reported at the conference is being supported by the U.S. government.

Table 1.1. Lead-author affiliation of the 263 general papers and 137 tropical cyclone-related papers originally scheduled for presentation at the AMS 21st Conference on Hurricanes and Tropical Meteorology. Domestic universities include eight tropical cyclone papers from the U.S. Naval Postgraduate School (NPS).

1.3.2 NOAA. Table 1.2 is a breakdown of the rather large number of papers (45) presented by NOAA groups. Of these, 32 were tropical cyclone-related, and more than half (20) of these papers are from the NOAA HRD/AOML. Although the number of papers from the former National Hurricane Center is rather small, it should be pointed out TPC is primarily a forecasting rather than a research center.

1.3.3 U.S. Universities. Table 1.3 is a breakdown of the lead-author affiliation of the 32 U.S. universities represented at the conference. Colorado State, Pennsylvania State, Florida State, the U.S. Naval Postgraduate School, and several other universities are quite involved in research associated with tropical cyclones and tropical meteorology.

Table 1.2. Numbers of papers presented by NOAA-affiliated lead authors.

Table 1.3. Numbers of papers presented by U.S. university-affiliated authors, including students.

Listing includes the U.S. Naval Postgraduate School and universities in Guam and Puerto Rico.

Certainly, other universities not listed in Table 1.3 are conducting research related to tropical cyclones but, for one reason or another, did not participate in the conference. An example would be the University of Massachusetts, which is collaborating with the NOAA HRD/AOML and NASA on the use of Stepped-Frequency Microwave Radiometer (SFMR) and C-band Scatterometer (C-SCAT) data in determining surface wind fields in tropical cyclones.

1.3.4 Foreign Meteorological Services. There were a substantial number of papers from foreign meteorological services. The countries represented were: Australia, France, Russia, Britain, Taiwan, and the People's Republic of China. As is typical for conferences of this type, the authors from some of the foreign meteorological services did not appear at the conference, presumably because of lack of funding. It is also noted in Table 1.1 that the number of lead authors from the private sector is very small.

1.4 Sources of Research Support (Summary). As pointed out earlier, tropical cyclone research is conducted at scores of national and international universities, at federal laboratories and technical agencies, and at national meteorological centers. Funding comes from several sources. The leading contributors are ONR, NOAA, NASA, and NSF. Other sources include the U.S. Army, the Federal Emergency Management Agency (FEMA), and various power companies and insurance companies. In the DOD, the Navy is tasked to provide research leading to the basic understanding of tropical cyclone motion and structure, and with improving tropical cyclone prediction.

1.4.1 TPC. For a number of years, the TPC has maintained a small in-house staff of techniques development meteorologists responsible for improving forecaster efficiency and forecast accuracy. Activities include storm surge studies, developing and maintaining statistical-dynamical and other hurricane track prediction models, evaluating regional and global numerical models, conducting forecast verification studies and data archiving. The unit was reorganized as part of the Technical Support Branch (TSB) with a branch chief and responsibilities have been expanded to include internal TPC computer operations (see section 1.2.1).

There are many advantages in having an in-house staff of techniques development meteorologists. As at other centers, the TPC uses numerous diagnostic and prognostic aids that continually need monitoring and updating. The ability to recognize technical guidance problems as they occur and immediately correct them or take steps to correct them without going through various time-consuming channels is one of these major advantages.

For the most part, the TPC techniques development efforts are strictly applied. A much more in-depth research effort is provided by the HRD/AOML. Although HRD/AOML is not physically collocated with the TPC, the two units are only a few miles apart, and active cooperation exists between the two groups. HRD/AOML tests experimental forecast and analysis tools at TPC and regularly assigns researchers to assist TPC during periods of tropical cyclone activity.

For a number of years, the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey, has been developing a hurricane model in support of the NOAA hurricane forecasting mission. As documented later in this document, the GFDL model is now the official NOAA hurricane model. GFDL will continue to work on improvements to this model.

Work in support of the NOAA hurricane mission is also conducted at NCEP's Environmental Modeling Center (EMC) and at NESDIS. Several universities also conduct NOAA and ONR supported research aimed at improved tropical cyclone prediction.

1.4.2 CPHC. The CPHC basically uses the same research and technique development channels as the TPC, namely the resources of HRD/AOML and the TPC/TSB. Additional tropical cyclone model research is obtained from GFDL. Other research resources are available through a unique association with the Department of Meteorology at the University of Hawaii. The CPHC also uses the results of research funded outside of NOAA.

1.4.3 JTWC. Although several research channels exist for JTWC and NAVPACMETOCCEN, the primary source is through ONR for basic research and through the Naval Research Laboratory (NRL) for applied research. ONR invests about $2.4 million per year in tropical cyclone research through its Marine Meteorology Office, which evaluates proposals, primarily from U.S. and foreign universities, and selects the proposals that most closely satisfy the needs of the Navy. In addition to universities, proposals from meteorological centers and research laboratories are also entertained. In DOD budgetary terms, this basic research is designated as 6.1-type funds.

ONR also supports some applied research initiatives, employing funds designated as 6.2. These focus on improving meteorological prognostic models. Another current initiative employs a multispectral approach to improving knowledge about tropical cyclone structure and structure change. Further applied research is funded by the Navy Space and Warfare Systems Office (SPAWRS). This funding is in the realm of 6.3 and 6.4 prototype and techniques development.

JTWC also uses results of research conducted by other agencies and universities not directly funded by the DOD. This includes national and international research from universities, environmental research laboratories, tropical cyclone warning centers, etc.

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