Geographical Simulation and Optimization System (GeoSOS)
The North American Soil Moisture Database (NASMD) was initiated in 2011 to assemble and homogenize in situ soil moisture measurements from 32 observational networks in the United States and Canada encompassing more than 1,800 stations. Although statistical quality control (QC) procedures have been applied in the NASMD, soil moisture content tends to be systematically underestimated by in-situ sensors in frozen soils, and using a single maximum threshold (i.e., 0.6 m3 m-3) may not be sufficient for robust QC because of the diverse soil textures in North America. Based on the in situ soil porosity and the North American Land Data Assimilation System phase 2 (NLDAS-2) Noah soil temperature, the simple automated QC method published in Xia et al. (2015) is revised to supplement the existing QC approach. The revised methodology includes a geophysical range check (GR check), a soil porosity check (SP check), and a soil temperature check (ST0 check).
We have generated a quality-controlled daily in situ soil moisture database based on the NASMD. The quality-controlled database includes 1,123 observation stations from 18 networks that are located in the NLDAS domain and have soil moisture measurement records in the original NASMD. Soil moisture measurements are flagged as “-9999” if 1) the value falls outside the geophysical range of 0 to 0.6 m3 m-3; 2) the value exceeds the corresponding soil porosity estimated based on the in situ soil texture; and 3) the corresponding soil temperature drops below zero.
(a) Map of observation stations included in the North American Soil Moisture Database (NASMD) with the background map indicating topography; (b) locations of example stations in Soil Climate Analysis Network (SCAN) used for evaluation and generation of the automated quality control with the background map indicating NLDAS-2 Noah soil porosity (m3 m-3).
The quality-controlled database is available to download in: Here
Weilin Liao, Dagang Wang, Guiling Wang, Youlong Xia, Xiaoping Liu, 2019: Quality Control and Evaluation of the Observed Daily Data in North American Soil Moisture Database. J. Meteor. Res.
We thank the scientists to maintain the soil moisture networks used in this study. We also appreciate Steven M. Quiring and his group for collecting in situ soil moisture observation to form the NASMD (it is currently changed to national soil moisture network, http://nationalsoilmositure.com). Without their efforts and support, it would not be possible to accomplish this work. Author Dagang Wang would like to acknowledge the National Key Research and Development Program of China (grant 2017YFA0604300) and the National Natural Science Foundation of China (grant 51779278). Author Youlong Xia would like to acknowledge partial financial support from NOAA/CPO Modeling, Analyses, Predictions and Projections (MAP) program. Author Xiaoping Liu would like to acknowledge the National Natural Science Foundation of China (grant 41671398).
If you have any comments and suggestions, please contact Dr. Weilin Liao (liaowlin@mail2.sysu.edu.cn) or Prof. Dagang Wang (wangdag@mail.sysu.edu.cn)
Last updated: 25 January, 2019