•Typically, observations of surface soil moisture
must have an accuracy of better than 5% v/v.
•The greatest impact of temporal resolution was for 1 to 5 days, with greater time between observations having a marginal degradation.
•Observations at one-quarter to one-half the spatial resolution of the model/application is a good compromise.
•To achieve the best results, it is important that the model forcing and observations be unbiased, or the bias modelled as part of the assimilation framework.
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