Pdf characteristics of gldas soilmoisture data on the. Land data assimilation systems ldas aim to produce high quality fields of land surface states e. This study analyzed the reliability of soil moisture and land surface temperature simulated by gldas using advanced microwave scanning radiometerearth observing system amsre data for the periods of one year based on fuzzy comprehensive evaluation theory, results demonstrate that both of them are relatively believable, and the land surface. How can i get the soil moisture products freely online. The noah lsm was configured for nldas to have 4 soil moisture layers with thicknesses from top of 10cm, 30cm, 60cm, and 100cm for a total soil column depth of 2 meters. Correlations between antecedent soil moisture and precipitation suggest that regions of strong land. More details regarding the land surface parameter data changes can be found at the gldas project website. Intercomparison of satelliteretrieved and global land data. Groundwater and soil moisture conditions from gracefo data. For more information on the gldas project and model outputs please visit gldas.
The aggregated land water anomalies sum of soil moisture, snow, canopy water provided here can be used for comparison against and evaluations of the observations of gravity recovery and climate experiment grace and gracefo over land. The models represent different soil moisture averaging depths roughly 2, 5, and 10 cm in clm and 10 cm in noah and retrievals from amsre cband approximate the soil moisture in the top 1. Therefore, the gldas1 production stream will end with the march 2020 data. Land data assimilation system gldas, the standardized precipitation index spi, and a new multi satellite surface soil moisture product. All 4 soil layers use the same soil texture predominant surface soil classes shown above and thus use the same soil parameter values for all layers as well. Global land data assimilation system gldas ingests satellite and ground based observational data products. In this study, we intercompare soil moisture from in situ measurement, reanalysis data erainterim, land data assimilation system simulations the global land data assimilation system, gldas and two satellite remote sensing retrievals. Ers data is processed by the microwave remote sensing group at tu wien. May 07, 2020 surface soil moisture is the daily average of measurements at 05 cm depth, and root zone soil moisture rzsm is the daily average of measurements at 0100 cm depth. Comparison of smap, gldas and simulated soil moisture. Using groundbased measurements over continental china, the monthly scale forcing data precipitation and air temperature during 19792010 and model outputs runoff, water storage, and evapotranspiration during 200210 of gldas models focusing on gldas, version 1 gldas1noah. This data product, reprocessed in january 2020, is for gldas 2. That dataset includes fractions of sand, silt, and clay, and porosity, among other fields, and it is based on the fao soil map of the world linked to a global database of over 0 soil pedons sample cores. A comparison of gldas soil moisture anomalies against.
Soil moisture and soil temperature are provided at four vertical layers. In this paper, the applicability of soilmoisture sm datasets of gldas global land data assimilation system in an alpine region tibet plateau, tp is investigated. Nasas earth observing system data and information system eosdis is a key core capability in nasas earth science data systems program for archiving and distributing earth science data from multiple missions to users. Can be used for comparison and residual groundwater studies. The spatial distribution and coherence of soil moisture are investigated seasonally and under both wetting and drying conditions. Ascat surface soil moisture cdr2015 time series 12. The soil moisture visualizer allows users to compare soil moisture measurements from multiple sources figure legends, top left and. The basic soils information used in gldas was derived from the global soils dataset of reynolds, jackson, and rawls wrr2000, which is available online here. Ascata and b data are generated through the hsaf soil moisture project which can be accessed on the eumetsat hsaf soil moisture website. Scientists working under the soil moisture project of esas climate change initiative have harmonised data on soil moisture from different satellites dating back to 1978 to give us a longterm view of global soil moisture, as well as variations and trends in the water cycle. Frequently asked questions esa cci soil moisture website. When ascat and amsr2 soil moisture data were compared to gldas soil moisture, ascat water 2017, 9, 332 10 of 24 data tended to overestimate soil moisture, while amsr2 data significantly underestimated soil moisture m3m.
Global land data assimilation system gldas ingests satellite and groundbased observational data products. Pdf downscaling gldas soil moisture data in east asia through. This study focuses on the setting up of a soil moisture data collection network over an agricultural site in a tropical region in peninsular malaysia and on the validation of smos soil moisture. This latest release extends the dataset for 2 years, providing global soil moisture data up. An updated water balance module that describes the infiltration rates as a function of the vertical gradient in soil moisture.
Comparison of soil moisture in gldas model simulations and. In the noah model, the bottom layer temperature data set was also updated. Downscaling gldas soil moisture data in east asia through. This poster presents the longterm et climatology mean and monthly, derived from the 61year gldas 2 monthly 1. Therefore, for our calculation we took fixed soil water density equal to 998 kgm 3 and multiplied gldas values by 199. Ascat surface soil moisture cdr2014ext time series 12. Conversion to time series is performed by the repurpose package in the background. The global land data assimilation system gldas is generating a series of land surface state e. Our underlying hypothesis is that, if gldas soil moisture variability corresponds well with other proxies andor measurementsgenerally accepted to describe soil conditions worldwidethen this dataset can be further employed to complement other descriptions of soil moisture at the regional level, where there is a lack of reliable measurements. Data products data smap soil moisture active passive.
The global land data assimilation system gldas can produce global and continuous soil moisture data sets which have been used in many applications. The input data for our processing was downloaded from the goddard space flight center disc the mapped data available here is integrated total water content, obtained from the gldas output by summing the layers. With the upgraded land surface models lsms and updated forcing data sets, the gldas2. Esa nearly four decades of soil moisture data now available. Data assimilation techniques for incorporating satellite based hydrological products, including snow cover and water equivalent, soil moisture, surface temperature, and leaf area index, are now being implemented as part of a followon project funded by the nasa. The input data for our processing was downloaded from the goddard space. For example, in gldas the nearsurface soil moisture variable represents an average over the top 10 cm of soil, whereas era5 and gleam estimate surface soil moisture over the 5 cm of soil depth. Soil moisture is a key state variable in many hydrological processes. Scientists at nasas goddard space flight center generate groundwater and soil moisture drought indicators each week. Reliability evaluation of soil moisture and land surface.
Where can i get the soil moisture products feely online. Ascat surface soil moisture cdr2014 time series 12. They are based on terrestrial water storage observations derived from gracefo satellite data and integrated with other observations, using a sophisticated numerical model of land surface water and energy processes. Soil moisture data smex04 false color image developed from landsat 5 thematic mapper tm data for studying land cover features. However, the soil moisture pattern in regions reg3 and reg4 from clm4. Project goals ldas land data assimilation system nasa. Evaluation of gldas1 and gldas2 forcing data and noah model. The global land data assimilation system gldas is an important data source for global water cycle research. The global land data assimilation system gldas generates a series of land surface state e. In this study, a soil moisture downscaling model was developed using satellitederived variables targeting global land data assimilation system gldas soil. Monthly gridded global land data assimilation system gldas. Gldas land water content monthly get data grace tellus. Shades of red indicate vegetation in southern arizona, usa on 11 june 2004. It will be very kind of you who can provide me some useful information about soil.
The project has resulted in a massive archive of modeled and observed, global, surface meteorological data, parameter maps, and output which includes 1. Using advanced land surface modeling and data assimilation techniques, it generates optimal fields of land surface states and fluxes. Groundwater and soil moisture conditions from grace data assimilation. Soil moisture data can be collected by satellites measuring microwaves reflected or emitted by earths surface. The intensity of the measured signal depends on the amount of water in the soil. Global land data assimilation system version 2 hereafter, gldas2 has two components. Lband products from soil moisture ocean salinity smos and cband products from the japan aerospace exploration agency advanced microwave scanning. The mapped data available here is integrated total water content, obtained from the gldas output by summing the layers.
They show similar global pattern for drought duration, frequency and. The gldas soil moisture data is useful for modeling these scenarios and others, but only at global scales. Land data assimilation systems ldas aim to produce high quality fields of. Data assimilation techniques for incorporating satellite based hydrological products, including snow cover and water equivalent, soil moisture. Applications of remote sensing to soil moisture and. Soil moisture data national snow and ice data center. Gldas land water content monthly a graceindependent forward simulation of monthly land water storage changes currently using soil moisture, snow, and canopy water. The gldas system is described in the article by rodell et al 2004. Verification of top layer 010 cm soil moisture m m. Unified user interface at nasa, uui, data, ges disc, datasets. The highquality, global land surface fields provided by gldas support several current and proposed weather and climate prediction, water resources applications, and water cycle investigations. The entire collection will be aviable at the ges disc until june 30, 2020. A drawback of smmw for defining soil moisture amounts is that it uses climatological data from noah gldas 1 to define the range of variability of estimated soil moisture. Esa cci and gldasnoah are significantly correlated in soil moisture drought index.
A new data assimilation scheme that has been validated for australia martens et al. The simulations were forced by the global meteorological forcing data set from princeton university sheffield et al. In this paper, the applicability of soil moisture sm datasets of gldas global land data assimilation system in an alpine region tibet plateau, tp is investigated. Water free fulltext downscaling gldas soil moisture data in. The goal of the global land data assimilation system gldas is to. Intercomparison of soil moisture products from smos, amsre. A 3 km spatially and temporally consistent european daily.
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