THE CDDIS DATA CENTER — NASA'S SPACE GEODESY DATA ARCHIVE

Carey Noll and Maurice DubeNASA GSFC

120°105°90° 165°150°135°75°60°45°30°15°0°-15°-30°-45°-60°-75°-90°-105°-120°-135°-150°-165°

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30°

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60°

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GPS SiteGLONASSSLR SiteVLBI SiteDORIS Site

Fortaleza

Arequipa

Bogotá

Santiago

Brasilia

La Plata

Kourou

Easter Island

Galapagos Islands

Limón

Tahiti

Kokee Park

Mauna Kea St. Croix

Barbados

Key Biscayne

McDonald

North Liberty

Greenbelt

Ottawa

Lac du Bonnet

EnsenadaPie Town

Quincy

Albert HeadAlgonquin

Colorado SpringsWestford

Mammoth Lakes

St. John's

Washington, D.C.Southern California

Integrated GPS Network(over 50 sites)

Churchill

Schefferville

Penticton

Fairbanks

Flin Flon

HolbergNanoose Bay

Priddis

Ucuelet

Whitehorse

Williams Lake

Whistler

Yellowknife Reykjavík Höfn

Thule

Kangerlussuaq

O'HigginsPalmer

Casey

MawsonDavis

McMurdo

Auckland

Hobart

TidbinbillaPerth

Yaragadee (2)

Karratha

Jabiru

Townsville

NouméaAlice Springs

Macquarie Island

Chatham Islands

PretoriaHartebeesthoek

Sutherland

Rabat

Bahrain

Ascension

Maspalomas

Diego GarciaSeychelles

Cocos Islands

Singapore

Bakosurtanal

Kwajalein

Guam

Taipei

Tsukuba

Shanghai

Kunming

Xi'anWuhan

UsudaTaejonSuwon-shi

Gough Island

AnkaraMadrid

Nicosia

Borowiec

Brussels

Cagliaril'Ebre

KievOndrejov

Grasse

Graz

Herstmonceux

Innsbruk

Bangalore

IrkutskJozefoslaw

Kiruna

Kitab

KootwijkOlsztyn

Malindi

Matera

Mendeleevo

Medicina

Metsahovi

Noto

Yerevan

Ny Ålesund

Oberpfaffenhofen

Onsala

Penc

Mitzpe Ramon

San Fernando

SofiaToulouse

Tromsø

Padova

Villafranca

Westerbork

Zimmerwald

Zweningorod

Zelenchukskaya

Yakutsk

AlmatyBishkek

Petropavlovsk-Kamchatsky

Lhasa

Magadan

Krasnoyarsk

Sanae

-30°

Kerguélen

Genova

Chesapeake Bay(3 sites)

Bermuda

Eastport

Tiksi

South Pole

Urumqi

Wettzell

Yebes

Effelsberg

Simeiz

KashimaMiuraKoganeiTateyama

Mizusawa

Syowa

Fort Davis

Green Bank

Hancock

Brewster

Los Alamos

Owens Valley

Kitt Peak

Goldstone

Bar Harbor

Potsdam

Maidenak

Riyadh

Helwan

Katzively

Komsomolsk

Changchun

Beijing

Simosato

Mt. Stromlo

Haleakala

Monument Peak

Svetloe

Tokyo

Riga

Quezon CityKaygabok Taal

Bilibino

KumtorkalaTalasKhantau Chumysh

ShamsiGebze

Bucharest

Yamoussoukro

Rio Grande

Cordoba

Salta

Aguascalientes

Riobamba

Ohrid

VeneziaOsijek

Arti

Dubrovnik

Santiago de Cuba

Esteli

Chiliwack

Tegucigalpa

ManaguaSan LorenzoGuatemala City

San Salvadore

Richard's Bay

AmmanMetzoki Dragot

Yuzhno-Sakhalinsk

Noril'sk

Ceduna

Darwin

DiyarbakirTrabzon

Istanbul

Kingston

Libreville

Boras

Marion Island

Tristan de Cunha

Rothera

Amsterdam Island

Sainte-Helene

Cachoeira Paulista

La Reunion

DjiboutiColombo

Mt. Everest

Arlit

Ponta Delgada Dionysos

Cibinong

Dakar

Solcorro Island

Rapa

Richmond

Badary

Purple Mountain

Manila

Port Moresby

Terre Adéle

Novosibirsk

Woodinville

Visby

GjØvik

Neustrelitz

Maartsbo

Sèvres Mattersburg

Teddington

WroclawDelft

Mitaka

Lindfield

Brisbane

Poltava

Braunschweig

MbararaFranceville

Caucete

Coyhaique

Punta Arenas

Valparaiso

Faleolo

Futuna

HiloHonolulu

Lihue

Manzanillo

Freeport

Male

Lae

SuvaKoumac

Palmeira

Fredericton

LvivUzhgorod

American Samoa

La Rochelle

Resolute

Holman Island

Inuvik

Gatineau Huegelheim

DresdenFrankfurtTitz

Huegleheim

LeipzigHelgoland

Dunedin

GLOBAL GPS, GLONASS, LASER, VLBI, AND DORIS NETWORKS

CDDIS OVERVIEWThe Crustal Dynamics Data Information System (CDDIS) is a dedicated data center supporting the international space geodesy community, providing easy and ready access to a variety of data sets, products, and information about these data. The data center was established in 1982 as a dedicated data bank to archive and distribute all Crustal Dynamics Project-acquired data and information about these data. Today, the CDDIS continues to serve as the NASA archive and distribution center for space geodesy data, particularly Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), laser ranging, Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) data. The specialized nature of the CDDIS lends itself well to enhancement to accommodate diverse data sets and user requirements. The CDDIS serves as one of the primary data centers for the following International Association of Geodesy (IAG) services:•International GPS Service (IGS)•International Laser Ranging Service (ILRS)•International VLBI Service for Geodesy and Astrometry (IVS) •International Earth Rotation Service (IERS)•International DORIS Service (IDS) Operational data centers deposit data to individual user accounts on the CDDIS host computer. All data are processed to ensure data integrity and to extract pertinent metadata. These metadata are loaded into a relational database for data tracking and query purposes. Data are then copied to public directories and made available to the user community through anonymous ftp and the web. The CDDIS is operational on a UNIX server with over 550 Gbytes of on-line disk storage. A majority of the archive is devoted to the archive of GPS data and products. In 2001, over 2.2 million files totaling over 150 Gbytes in size were downloaded each month from the CDDIS on-line archive. More than 6,700 distinct hosts in 95 countries accessed and downloaded data from the CDDIS last year. Over 120 institutions in over sixty countries supply data to the CDDIS on a daily basis for

DORIS on-board receiverIDS web site photograph

DORIS antenna located inHartebeesthoek, South Africa

IGN web site photograph

DORIS satellite antennaAVISIO web site photograph

IDS DATA AND PRODUCTSThe DORIS system, developed in France, is based on the measurement of Doppler shifts in radio signals, transmitted by ground beacons to a DORIS receiver on-board the satellite. Like GPS and SLR, precise satellite orbits, positions of and distances between observing stations, and Earth rotation, orientation, and polar motion values can be derived from DORIS measurements. The primary objective of the International DORIS Service (IDS) is to foster the DORIS technique to support international geodetic, geophysical, and other research and operational activities.

DORIS Data:•Files containing one "cycle" (~ten days) of data (computedrange measurements), sorted by satellite, in DORIS-specific format•Seven satellites have on-board DORIS receivers that receive transmitted signals from a network of nearly 50 beacons•Approximately 5 Mbyte/satellite/cycle (compressed) •CDDIS DORIS data archive: 1992 through present; all data available on-line

IDS Products (future):•Precise satellite ephemerides•Site coordinates and velocities; position time series•Earth rotation parameters•Special products-Ionosphere information-Time varying geocenter coordinates

Network Stations Continuously operational Timely flow of data

Data Centers Interface to network stations Perform QC and data conversion activities Archive data for access to analysis centers and users

Analysis Centers Provide products to users (e.g., station coordinates, precise satellite orbits, Earth orientation parameters, atmospheric products, etc.)

Central Bureau Management of service Facilitate communications Coordinate activities

Governing Body General oversight of service Future direction

DATA FLOW FOR INTERNATIONAL SERVICES

Space Geodesy Network Stations

GPS GLON SLR VLBI DORIS

Operational/Regional Data Centers

Analysis Centers/User Community

Global Data Centers

Compressed Data Files (in data type-specific formats)

Compressed Data Files (in data type-specific formats)

Raw Data

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CEN 05/17/2002

FOR FURTHER INFORMATIONCarey NollManager, CDDISNASA GSFCGreenbelt, MD 20771USACarey.Noll@gsfc.nasa.gov

Maurice DubeRaytheon ITSSLanham, MD 20706USAmdube@pop900.gsfc.nasa.gov

CDDIS Web Site: http://cddis.nasa.gov or http://cddisa.gsfc.nasa.gov

IVS DATA AND PRODUCTSProducts generated by International VLBI Service for Geodesy and Astrometry (IVS) contribute to research in many areas, including solid Earth, tides, studies of the vertical, and VLBI technique improvement. The objectives of IVS are to provide a service to support geodetic, geophysical, and astrometric research and operational activities, to promote research and development for VLBI, and to interact with users of VLBI products

VLBI Data:•VLBI data bases in DBH and NGS card formats•Auxiliary files (e.g., log, met data, schedule, cable info, correlator notes, etc.)•Currently, over 40 antennas participate in the IVS•Approximately 2-3 Mbyte/data base file(compressed)•CDDIS VLBI data archive: 1979 through present; most data holdings available on-line

IVS Products:•Intensive and session Earth orientation parameter series (EOP-I and EOP-S)

VLBI antenna at Fairbanks, AKIVS web site photograph

Part of the celestial reference frame defined by VLBIIVS web site photograph

ILRS DATA AND PRODUCTSThe International Laser Ranging Service (ILRS), operational since 1998, provides global satellite and lunar laser ranging data and their related products to support geodetic and geophysical research

an accurate International Terrestrial Reference Frame (ITRF). The service develops the necessary global standards/specifications and encourages international adherence to its conventions. The ILRS collects, merges, archives and distributes Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) observation data sets of sufficient accuracy to satisfy the objectives of a wide range of scientific, engineering, and operational applications and experimentation.

Laser Data:• Daily and monthly files containing on-site normal points,

sorted by satellite, in ILRS normal point format• Hourly files containing on-site normal points from all

satellites, in ILRS normal point format retained for five days

• Daily and monthly full-rate data files from a subset of the global network, sorted by satellite, in ILRS full-rate format

• Currently, 26 satellites and four sites on the moon are tracked on a routine basis by 40 SLR and LLR stations

• Approximately 1 Mbyte/day on-site normal point data (uncompressed); 2 Mbytes/day full-rate data (compressed)

• CDDIS laser data archive: 1976 through present; approximately 90% of data holdings available on-line

ILRS Products (future):• Precise satellite ephemerides

Retroreflector array on Jason, GFO-1, ICEsat, and ADEOS-IIILRS web site photograph

LAGEOS satelliteILRS web site photograph

SLR 2000 prototype system at Greenbelt, MDILRS web site photograph

IGS DATA AND PRODUCTSThe main mission of the International GPS Service (IGS) is to provide a service to support geodetic and geophysical research activities through GPS data and products. This service has been operational since 1994. The current network consists of nearly 300 permanently occupied, globally distributed sites that provide GPS data to IGS data centers on a daily, hourly, and near-real-time basis. These GPS data are used by the IGS analysis centers to generate products such as precise satellite ephemerides and clock information.

GPS (and GLONASS) Data:•Daily files containing 30-second sampled GPS data in RINEX format-200+ GPS (and ~50 GLONASS) stations/day-Approximately 0.35 Mbytes/site/day in size (compressed)-Data since January 1997 on-line•Hourly files of 30-second sampled GPS data in RINEX format-115+ GPS (and 16 GPS/GLONASS) stations/day-Approximately 0.02 Mbytes/site/hour in size (compressed)-Data retained for three days•Fifteen-minute files of one-second sampled GPS data in RINEX format-40+ GPS stations/day-Approximately 0.45 Mbytes/site/hour in size (compressed)-Data since May 2001 on-line•Daily files of ten-second sampled satellite-borne GPS receive data in RINEX format-Two satellites (SAC-C, CHAMP); JASON, GRACE to be archived -Approximate 2.5 Mbytes/satellite/day in size (compressed)-Data since January 2002 on-line

IGS Products:•Precise GPS satellite ephemerides (<5 cm accuracy)•Earth rotation parameters •IGS tracking station coordinates and velocities •GPS satellite and IGS tracking station clock information• Global ionosphere maps of total electron content (TEC)

IGS

GPS satelliteSmithsonian Institution photograph

GODE GPS antenna at Greenbelt, MDCDDIS photograph

FAIR GPS antenna at Fairbanks, AKIGS photograph

CDDIS ARCHIVE STATISTICS

North AmericaSouth AmericaEuropeAsiaAfricaAustraliaPacific

Number of GPS, GLONASS, Laser, VLBI, and DORISFiles Retrieved in 2001

(By Geographic Area)

Number of GPS, GLONASS, Laser, VLBI, and DORISFiles Retrieved in 2001

(By Geographic Area)

57%

9%

29%

1%

4% <1%<1%

CommercialEducationGovernmentNetworkNon-ProfitUnknown

Number of GPS, GLONASS, Laser, VLBI, and DORIS Files Retrieved in 2001

(By Host Type)

Number of GPS, GLONASS, Laser, VLBI, and DORIS Files Retrieved in 2001

(By Host Type)

62%

11%

26%

1% <1%<1%

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100,000

1,000,000

10,000,000

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Number of GPS, GLONASS, Laser Ranging, VLBI and DORIS Files Retrieved from the CDDIS(2001)

Number of GPS, GLONASS, Laser Ranging, VLBI and DORIS Files Retrieved from the CDDIS(2001)

GPS GLONASS Laser VLBI DORIS