Locally Sponsored Research

Guam Hydrologic Survey

Data Availability Reports

Chapter 1: Meteorological Data
by: Peter-Paul G. Dumaliang, Charles P. Guard, & Danko S. Taboroši

This chapter discusses meteorological data collection activities on Guam. Current points of contact for the agencies and activities that collect or archive groundwater data are summarized in Table 1.1.

Table 1.1. Meteorological data collection agencies, archives, and points of contact

Agency Point of Contact Contact
USGS Barry R. Hill, Asst. District Chief,
Hawaii, USGS
Phone: (808) 522-8290
brhill(usgs)usgs.gov?subject=Contact - USGS
NWS Dave Meek, Data Manager, NWS Phone: (671) 472-7397
Air Force
AGAN Keith Holder
Sgt. Ronald Bridges
Phone: (671) 349-5314
holder(navy)npmocw.navy.mil?subject=Contact - Navy
Phone: (671) 366-5230
bridgesr(andersen)andersen.af.mil?subject=Contact -Air Force
Private Sector Jane Jameson Williams
Clay Carlson
Kuentos Communications Inc.
Phone: (671) 477-9109
Fax: (671) 477-4218
info(kuentos)kuentos.guam.net?subject=Contact - Private Sector
Charles Guard, WERI Research Associate
Prem Singh, Professor
Phone: (671) 735-2695
cguard(uog)uog.edu?subject=Contact - WERI
Phone: (671) 735-2000
JTWC Edward Fukada, Technical Advisor Phone: (671) 349-5286/7
PEAC Ray Tanabe, Pacific ENSO Update Phone: (808) 956-2324

Abbreviations: USGS-United States Geologic Survey, NWS-National Weather Service, UOG-University of Guam, WERI-Water and Energy Research Institute of the Western Pacific, CALS-College of Agriculture and Life Sciences, JTWC-Joint Typhoon Warning Center, PEAC-Pacific ENSO Applications Center


Local Data Collection Activity & Points of Contact

Several different agencies collect meteorological data on Guam. Data collected range from local rainfall, wind, and temperature to regional rainfall and typhoon-related data. The primary collectors of local weather data are the US Geological Survey, National Weather Service, US Air Force, and the US Navy. The University of Guam and some private citizens collect local rainfall data as well. The National Weather Service (NWS) collects meteorologic data and reports on regional and local weather conditions. The Joint Typhoon Warning Center (JTWC) monitors tropical cyclone development and movement and issues tropical cyclone advisories for the U.S. Department of Defense. The Pacific ENSO Applications Center (PEAC) consolidates and archives regional and local data, including regional Pacific rainfall data, and also issues long-range rainfall forecasts for Micronesia, Hawaii and other Pacific islands. The locations and methods of collection vary. Data collection stations and the types of data collected are shown in Figure 1.1. Data collection activities are described below.


U.S. Geological Survey (USGS)

From 1954 to the present, the USGS has recorded local rainfall at various times from a total of 16 sites. As of September 1998, the USGS operates 6 rain gages on Guam. Three of these—the Fena Pump House, Almagosa, and Windward Hills gages—are operated for the US Navy. Gages at Mt. Chachao, Dededo, and Umatac are to be operated for WERI under the WERI/USGS data collection program beginning during FY 1999. All of the USGS gages are float-reservoir type gages. Data are recorded by electronic data loggers at 30-minute intervals. Personnel from the Saipan field office visit Guam at the beginning of each month to download data from the data loggers at the Navy sites. WERI/USGS sites are to be serviced quarterly by personnel from the Hawaii office. Historical data through 1989 have been published. Data since 1989 are available from the Honolulu office, but are considered preliminary.

National Weather Service (NWS)

The National Weather Service Office (NWSO) currently maintains thirteen rain gauges on the island, of which seven are automatic and six are manual (Figure 1.1 and Table 1.2). Data from the three Fisher & Porter automatic rain gauges at Dededo, Mangilao and Tiyan are sent monthly to the Pacific Region NWS headquarters in Honolulu, Hawaii. Data collected by the NWS’s HANDAR sites are not routinely archived, and only near real-time data can be obtained from NWS on request. The manual stations are cooperative sites, i.e., the gages are maintained by NWS but operated by cooperating agencies (Table 1.2). These are mostly manually measured 8-inch rain cans. Rainfall data archived by the NWS are stored in the National Climate Data Center (NCDC) database and in unpublished paper spreadsheets.

The NWS collects and archives selected satellite data for the region. The Doppler radar in Mangilao, owned and operated by the U.S. Air Force, collects cloud reflectivity and Doppler velocity (of the target) data. Primary data are processed, and secondary data, such as accumulated rainfall, are calculated. At the NWS office, archived data include temperature, wind speed and direction, atmospheric pressure, relative humidity, dew point, visibility, heat index, sky conditions, sunrise and sunset, cooling degree days, occurrence of thunderstorms and percent possible sunshine. These data are updated regularly and reported on the NWSO Guam web page (http://www.nws.noaa.gov/pr/guam/). They are also available in the Climatological Data Summaries published by the NCDC in Asheville, NC.

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Table 1.2
NWS and NWS-cooperative rain gages and description.

Automatic Tipping-Bucket Rain Gage Sites

Location Type of Station Database
Agat Fire Station Cooperative NCDC; NWSO Guam
Commercial Port NWS HANDAR Not archived; can be downloaded
Fena Lake (Naval Magazine) NWS* (rain gage only) Pacific Reg. HQ NWS Honolulu
Mangilao (Univ. of Guam) NWS HANDAR Not archived; can be downloaded
Merizo (Mayor’s Office) NWS HANDAR Not archived; can be downloaded
NASA Dan Dan (State Dept.) NWS HANDAR* Pacific Reg. HQ NWS Honolulu
Piti Fire Station Cooperative* Pacific Reg. HQ NWS Honolulu

* = Fischer & Porter Type Tipping-Bucket Rain Gage


Manual 8” Can Sites

Location Type of Station Database
WSFO Tiyan NWS Official NCDC; NWSO Guam
Dededo (Guam Waterworks A.) Cooperative NCDC; NWSO Guam
Inarajan (Agricultural Station) Cooperative NCDC; NWSO Guam
Mangilao (Dept. of Agriculture) Cooperative NCDC; NWSO Guam
Umatac (Guam Waterworks A.) Cooperative NWSO Guam
Yigo (Animal Shelter) Cooperative NCDC; NWSO Guam

Abbreviations: NCDC = National Climatic Data Center, NWS = National Weather Service,
NWSO = National Weather Service Office

Note: Talofofo Golf Course cooperative site was destroyed in Typhoon Paka, December 1997, and has not been reactivated.

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The US Air Force collects meteorological data at Andersen Air Force Base including rainfall variability, wind, temperature, dew point, pressure, and cloud cover. Data are collected in hourly increments and archived in the NCDC database (OK). The US Navy collects rainfall data at Nimitz Hill and at the Naval Magazine (Figure 1.1). These data are collected either manually or automatically at these sites, and are stored electronically in spreadsheets.

University of Guam

The University of Guam has four data collections sites: one in Talofofo, one at Andersen Air Force Base, one at Inarajan and one in Yigo (Figure 1.1). The Talofofo and the Andersen AFB sites are maintained by the Water & Energy Research Institute (WERI). The Talofofo site contains a tipping-bucket rain gauge and data logger, which collects and records rainfall data at one-minute intervals. Data collection at this site started on September 1st, 1986. The Andersen AFB site has 2 side-by-side tipping-bucket rain gauges and a datalogger that collects data at 0.01-inch intervals. Data collection at this site started June 1st, 1998. The Inarajan and Yigo sites are maintained by the College of Agriculture and Life Science (CALS). Inarajan site is located at the Inarajan Agricultural Experiment Station, and has been operating since 1984. Yigo site is located at ______ and data collection here started in _____, Both sites are equiped with tipping-bucket rain gages, with data loggers, which collect and record hourly rainfall. In addition, both sites collect data on the temperature, humidity, solar flux and wind speed and direction. [This info is from Dr. Singh’s assistant. I’m still waiting for an e-mail reply from Dr. Singh. (Danko)]


Three private data collection stations are currently maintained (Figure 1.1). Data collected and recorded are mainly monthly rainfall data. Most are currently recorded in electronic spreadsheets. Ms. Jane Jameson-Williams maintains a site on Nimitz Hill. Mr. Clay Carlson maintains rain gauges in Bili Bay, Merizo and Tinaga, Inarajan. They have generously provided data for several recent studies, most recently a soil erosion study (Dumaliang, 1998). Kuentos Communications Inc., a commercial communications company, maintains an automatic weather station in Maite. These data are made available for special studies, such as Typhoon Paka’s rainfall.

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Regional Meteorological Data Collection Activities

Typhoon-related data are currently being collected by the Joint Typhoon Warning Center JTWC at Nimitz Hill. Data are kept in both published reports and at the JWTC web site, http://metoc.npmocw.navy.mil/npmocw/prods/jtwc.html. The JTWC is scheduled to relocate from Guam to Pearl Harbor, Hawaii in January 1999. Rainfall Data for Micronesia and American Samoa are reported by the Pacific ENSO Application Center (co-located at the University of Guam and the University of Hawaii) in their Pacific ENSO Newsletter. Data can be accessed from their web site at http://naulu.soest.hawaii.edu/. WERI meteorologists also collect typhoon- and ENSO-related satellite data. WERI will have a real-time meteorological satellite imagery processing and display system beginning August 1998.

Data Archives

Meteorological data for Guam and the western Pacific region are archived in various locations and are accessible through different media. USGS published rainfall data report for the year 1989 in Volume 2 of Water Resources Data – Hawaii and Other Pacific Areas. Copies of these reports are held at GEPA, WERI, and at the UOG RFK Memorial Library. Reports can also be purchased from the US Department of Commerce (NTIS, 5285 Port Royal Road, Springfield, VA 22161). Published USGS data are also available on the USGS web site at http://waterdata.usgs.gov/nwis-w/HI/. Historical data are also available on a commercial CD-ROM database, Climatedata, prepared by Hydrosphere®. WERI maintains a subscription to Climatedata but there is typically about a one-year delay between data collection and publication in the CD-ROM database. Tables 1.1 summarizes the points of contact for agencies that collect and archive data.

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