|Van Oevelen, P|
Submitted to: Hydrology and Earth System Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2011
Publication Date: 8/11/2011
Publication URL: http://handle.nal.usda.gov/10113/59913
Citation: Dorigo, W.A., Wagner, W., Hohensinn, R., Hahn, S., Paulik, C., Drusch, Mecklenburg, S., Van Oevelen, P., Robock, A., Jackson, T.J. 2011. The international soil moisture network: A data hosting facility for global in situ soil moisture measurements. Hydrology and Earth System Sciences. 15:1675-1698. Interpretive Summary: An International Soil Moisture Network (ISMN) of in situ observing stations and data archival was established. In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. The international nature of these products and applications requires collaborative efforts, which has been difficult to establish. Accomplishing this required standardization of technique and measurement and in many cases the reanalysis and harmonizing existing data sets. With the establishment of the ISMN, an important step has been taken toward a global soil moisture observing system. Although soil moisture is now recognized as an essential climate variable, the growth and continuity of this effort will depend upon the commitment and the cooperation of data providers on a long-term basis. To reach the goal of a fully integrated global soil moisture observing system it will be necessary to establish, expand and improve current soil moisture observations, both in situ and remotely sensed. The database is rapidly expanding, which means that both the number of stations and the time period covered by the existing stations are still growing. As the ISMN is fed and utilized by the scientific community it will become a valuable resource for validating and improving satellite-derived soil moisture products and studying climate related trends.
Technical Abstract: In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, long-term time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations measuring soil moisture, in particular on a continuous basis, is still limited and the data they provide lack standardization of technique and protocol. To overcome many of these limitations, the International Soil Moisture Network (ISMN; http://www.ipf.tuwien.ac.at/insitu) was initiated to serve as a centralized data hosting facility where globally available in situ soil moisture measurements from operational networks and validation campaigns are collected, harmonized, and made available to users. Data collecting networks share their soil moisture datasets with the ISMN on a voluntary and no-cost basis. Incoming soil moisture data are automatically transformed into common volumetric soil moisture units and checked for outliers and implausible values. Apart from soil water measurements from different depths, important metadata and meteorological variables (e.g., precipitation and soil temperature) are stored in the database. These will assist the user in correctly interpreting the soil moisture data. The database is queried through a graphical user interface while output of data selected for download is provided according to common standards for data and metadata. Currently (status January 2011), the ISMN contains data of 14 networks and more than 500 stations located in the North America, Europe, Asia, and Australia. The time period spanned by the entire database runs from 1952 until the present, although most datasets have originated during the last decade. The database is rapidly expanding, which means that both the number of stations and the time period covered by the existing stations are still growing. As the ISMN is fed and utilized by the scientific community it will become a valuable resource for validating and improving satellite-derived soil moisture products and studying climate related trends. We invite potential networks to enrich the collection by sharing their in situ soil moisture data.