Le système d'assimilation des données terrestres (LDAS, Land Data Assimilation System) combine plusieurs sources d'observations (telles que les données des pluviomètres, les données satellite et les mesures radar des précipitations) pour produire des estimations des propriétés climatologiques à la surface de la Terre ou à proximité.
Cet ensemble de données est le fichier de forçage principal (par défaut) (fichier A) pour la phase 2 du North American Land Data Assimilation System (NLDAS-2).
Les données sont espacées d'un huitième de degré sur la grille et la résolution temporelle est d'une heure.
NLDAS est un projet collaboratif entre plusieurs groupes : le Centre de modélisation environnementale (EMC) de NOAA/NCEP, le Centre de vol spatial Goddard (GSFC) de la NASA, l'université de Princeton, l'université de Washington, l'Office of Hydrological Development (OHD) de NOAA/NWS et le Centre de prévision climatique (CPC) de NOAA/NCEP. NLDAS est un projet essentiel soutenu par le programme de prévision climatique pour les Amériques (CPPA) de la NOAA.
Température de l'air à 2 mètres au-dessus de la surface
specific_humidity
Fraction massique
0*
0,02*
mètres
Humidité spécifique à 2 mètres au-dessus de la surface
pressure
Pa
61 847,6*
105338*
mètres
Pression de surface
wind_u
m/s
-27,93*
27,54*
mètres
Composante U du vent à 10 mètres au-dessus de la surface
wind_v
m/s
-27,45*
35.13*
mètres
Composante V du vent à 10 mètres au-dessus de la surface
longwave_radiation
W/m^2
72.18*
545.11*
mètres
Rayonnement de grandes longueurs d'onde descendant à la surface
convective_fraction
0*
1*
mètres
Fraction des précipitations totales qui sont convectives : à partir de NARR
potential_energy
J/kg
0*
76666.2*
mètres
Énergie potentielle de convection disponible (J/kg) : à partir de NARR
potential_evaporation
kg/m^2
0*
2.76*
mètres
Évaporation potentielle : à partir de NARR
total_precipitation
kg/m^2
0*
124.19*
mètres
Précipitations totales par heure
shortwave_radiation
W/m^2
0*
1368.54*
mètres
Radiation à ondes courtes descendantes en surface : biais corrigé
* valeur minimale ou maximale estimée
Propriétés des images
Propriétés de l'image
Nom
Type
Description
end_hour
DOUBLE
Heure de fin
start_hour
DOUBLE
Heure de départ
Conditions d'utilisation
Conditions d'utilisation
La distribution des données du Goddard Earth Sciences Data and Information Services Center (GES DISC) est financée par la Science Mission Directorate (SMD) de la NASA. Conformément à la politique de la NASA sur les données et informations scientifiques sur la Terre, les données de l'archive GES DISC sont disponibles sans frais pour la communauté des utilisateurs.
Pour en savoir plus, consultez la page Règles concernant les données du GES DISC.
Citations
Citations :
La source de l'ensemble de données doit être correctement citée lorsque les données sont utilisées. Référence formelle au format suivant : \<auteurs\\>, 2012, dernière mise à jour 2013 : \. NASA/GSFC, Greenbelt, MD, USA, NASA Goddard
Earth Sciences Data and Information Services Center (GES DISC).
Accessed \ at \<doi\\> is suggested following
Parsons et al. (2010), doi:10.1029/2010EO340001.</doi\\></authors\\>
Le système d'assimilation des données terrestres (LDAS, Land Data Assimilation System) combine plusieurs sources d'observations (telles que les données des pluviomètres, les données satellite et les mesures radar des précipitations) pour produire des estimations des propriétés climatologiques à la surface de la Terre ou à proximité. Cet ensemble de données est le fichier de forçage principal (par défaut) (fichier A) pour la phase 2 de la …
[null,null,[],[[["\u003cp\u003eThe NASA NLDAS FORA0125 H002 dataset provides hourly estimates of climatological properties like temperature, humidity, and precipitation across North America.\u003c/p\u003e\n"],["\u003cp\u003eIt combines observations from various sources, including precipitation gauges, satellite data, and radar measurements, to generate these estimates.\u003c/p\u003e\n"],["\u003cp\u003eThis dataset covers the period from January 1, 1979, to December 9, 2024, with a spatial resolution of 1/8th degree.\u003c/p\u003e\n"],["\u003cp\u003eNLDAS is a collaborative project involving NOAA, NASA, and several universities, and it serves as the primary forcing dataset for the North American Land Data Assimilation System (NLDAS-2).\u003c/p\u003e\n"],["\u003cp\u003eData is freely accessible and can be used for research, education, and nonprofit purposes through platforms like Google Earth Engine.\u003c/p\u003e\n"]]],["The dataset, provided by NASA GES DISC, covers 1979-01-01 to 2025-02-18 with hourly cadence. It's the primary forcing file for NLDAS-2, offering 1/8th-degree grid spacing, and it compiles data from various sources like gauges, satellites, and radar. Key climatological properties are available, including temperature, humidity, pressure, wind, radiation, and precipitation, among others. The data is available for free use under NASA's Earth Science Data and Information Policy. Users can access and analyze the data using Google Earth Engine.\n"],null,["Dataset Availability\n: 1979-01-01T13:00:00Z--2025-09-01T12:00:00Z\n\nDataset Provider\n:\n\n\n [NASA GES DISC at NASA Goddard Space Flight Center](https://doi.org/10.5067/6J5LHHOHZHN4)\n\nCadence\n: 1 Hour\n\nTags\n:\n [climate](/earth-engine/datasets/tags/climate) [evaporation](/earth-engine/datasets/tags/evaporation) [forcing](/earth-engine/datasets/tags/forcing) [geophysical](/earth-engine/datasets/tags/geophysical) [hourly](/earth-engine/datasets/tags/hourly) [humidity](/earth-engine/datasets/tags/humidity) [ldas](/earth-engine/datasets/tags/ldas) [nasa](/earth-engine/datasets/tags/nasa) [precipitation](/earth-engine/datasets/tags/precipitation) [pressure](/earth-engine/datasets/tags/pressure) [radiation](/earth-engine/datasets/tags/radiation) [soil](/earth-engine/datasets/tags/soil) [temperature](/earth-engine/datasets/tags/temperature) [water-vapor](/earth-engine/datasets/tags/water-vapor) [wind](/earth-engine/datasets/tags/wind) \nnldas \n\nDescription \nLand Data Assimilation System (LDAS) combines multiple\nsources of observations (such as precipitation gauge data, satellite\ndata, and radar precipitation measurements) to produce estimates\nof climatological properties at or near the Earth''s surface.\n\nThis dataset is the primary (default) forcing file (File A) for\nPhase 2 of the North American Land Data Assimilation System (NLDAS-2).\nThe data are in 1/8th-degree grid spacing; the temporal resolution\nis hourly.\n\nNLDAS is a collaboration project among several groups: NOAA/NCEP''s\nEnvironmental Modeling Center (EMC), NASA''s Goddard Space Flight\nCenter (GSFC), Princeton University, the University of Washington,\nthe NOAA/NWS Office of Hydrological Development (OHD), and the\nNOAA/NCEP Climate Prediction Center (CPC). NLDAS is a core project\nwith support from NOAA''s Climate Prediction Program for the Americas\n(CPPA).\n\nDocumentation:\n\n- [Readme](https://hydro1.gesdisc.eosdis.nasa.gov/data/NLDAS/README.NLDAS2.pdf)\n\n- [How-To](https://disc.gsfc.nasa.gov/information/howto?tags=hydrology)\n\n- [GES DISC Hydrology Documentation](https://disc.gsfc.nasa.gov/information/documents?title=Hydrology%20Documentation)\n\n- [GES DISC Data Rods Documentation](https://disc.gsfc.nasa.gov/information/tools?title=Hydrology%20Data%20Rods)\n\nBands\n\n\n**Pixel Size**\n\n13915 meters\n\n**Bands**\n\n| Name | Units | Min | Max | Pixel Size | Description |\n|-------------------------|---------------|-----------|-----------|------------|---------------------------------------------------------------|\n| `temperature` | °C | -49.79\\* | 51.2\\* | meters | Air temperature at 2 meters above the surface |\n| `specific_humidity` | Mass fraction | 0\\* | 0.02\\* | meters | Specific humidity at 2 meters above the surface |\n| `pressure` | Pa | 61847.6\\* | 105338\\* | meters | Surface pressure |\n| `wind_u` | m/s | -27.93\\* | 27.54\\* | meters | U wind component at 10 meters above the surface |\n| `wind_v` | m/s | -27.45\\* | 35.13\\* | meters | V wind component at 10 meters above the surface |\n| `longwave_radiation` | W/m\\^2 | 72.18\\* | 545.11\\* | meters | Surface downward longwave radiation |\n| `convective_fraction` | | 0\\* | 1\\* | meters | Fraction of total precipitation that is convective: from NARR |\n| `potential_energy` | J/kg | 0\\* | 76666.2\\* | meters | Convective available potential energy (J/kg): from NARR |\n| `potential_evaporation` | kg/m\\^2 | 0\\* | 2.76\\* | meters | Potential evaporation: from NARR |\n| `total_precipitation` | kg/m\\^2 | 0\\* | 124.19\\* | meters | Hourly total precipitation |\n| `shortwave_radiation` | W/m\\^2 | 0\\* | 1368.54\\* | meters | Surface downward shortwave radiation - bias corrected |\n\n\\* estimated min or max value\n\nImage Properties\n\n**Image Properties**\n\n| Name | Type | Description |\n|------------|--------|-------------|\n| end_hour | DOUBLE | End hour |\n| start_hour | DOUBLE | Start hour |\n\nTerms of Use\n\n**Terms of Use**\n\nDistribution of data from the Goddard Earth Sciences\nData and Information Services Center (GES DISC) is funded by NASA's\nScience Mission Directorate (SMD). Consistent with NASA [Earth\nScience Data and Information Policy](https://www.earthdata.nasa.gov/engage/open-data-services-and-software/data-and-information-policy/),\ndata from the GES DISC archive are available free to the user community.\nFor more information visit the GES DISC [Data Policy](https://disc.sci.gsfc.nasa.gov/citing)\npage.\n\nCitations \nCitations:\n\n- The data set source should be properly cited when the data are\n used. A formal reference of the form: \\\\, 2012, last updated 2013: \\\\. NASA/GSFC, Greenbelt, MD, USA, NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). Accessed \\\\ at \\\\ is suggested following Parsons et al. (2010), [doi:10.1029/2010EO340001](https://doi.org/10.1029/2010EO340001).\n\nExplore with Earth Engine **Important:** Earth Engine is a platform for petabyte-scale scientific analysis and visualization of geospatial datasets, both for public benefit and for business and government users. Earth Engine is free to use for research, education, and nonprofit use. To get started, please [register for Earth Engine access.](https://console.cloud.google.com/earth-engine)\n\nCode Editor (JavaScript) \n\n```javascript\nvar dataset = ee.ImageCollection('NASA/NLDAS/FORA0125_H002')\n .filter(ee.Filter.date('2018-07-01', '2018-07-30'));\nvar temperature = dataset.select('temperature');\nvar temperatureVis = {\n min: -5.0,\n max: 40.0,\n palette: ['3d2bd8', '4e86da', '62c7d8', '91ed90', 'e4f178', 'ed6a4c'],\n};\nMap.setCenter(-110.21, 35.1, 4);\nMap.addLayer(temperature, temperatureVis, 'Temperature');\n```\n[Open in Code Editor](https://code.earthengine.google.com/?scriptPath=Examples:Datasets/NASA/NASA_NLDAS_FORA0125_H002) \n[NLDAS-2: North American Land Data Assimilation System Forcing Fields](/earth-engine/datasets/catalog/NASA_NLDAS_FORA0125_H002) \nLand Data Assimilation System (LDAS) combines multiple sources of observations (such as precipitation gauge data, satellite data, and radar precipitation measurements) to produce estimates of climatological properties at or near the Earth''s surface. This dataset is the primary (default) forcing file (File A) for Phase 2 of the North American ... \nNASA/NLDAS/FORA0125_H002, climate,evaporation,forcing,geophysical,hourly,humidity,ldas,nasa,precipitation,pressure,radiation,soil,temperature,water-vapor,wind \n1979-01-01T13:00:00Z/2025-09-01T12:00:00Z \n24.85 -125.15 53.28 -66.85 \nGoogle Earth Engine \nhttps://developers.google.com/earth-engine/datasets\n\n- [](https://doi.org/https://doi.org/10.5067/6J5LHHOHZHN4)\n- [](https://doi.org/https://developers.google.com/earth-engine/datasets/catalog/NASA_NLDAS_FORA0125_H002)"]]
