Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-338
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
27 Jul 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Hydrology and Earth System Sciences (HESS) and is expected to appear here in due course.
Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model
Peter J. Shellito and Eric E. Small Geological Sciences, University of Colorado Boulder, Boulder, 80309, USA
Abstract. Drydown periods that follow precipitation events provide an opportunity to assess the mechanisms by which soil moisture dissipates from the land surface. We use SMAP (Soil Moisture Active Passive) observations and Noah simulations from drydown periods to quantify the role of soil moisture, potential evaporation, vegetation cover, and soil texture on soil drying rates. Rates are determined using finite differences over intervals of 1 to 3 days. In the Noah model, the drying rates are a good approximation of direct soil evaporation rates. Data cover the domain of the North American Land Data Assimilation System phase 2 and span the first 1.8 years of SMAP's operation.

Drying of surface soil moisture observed by SMAP is faster than that simulated by Noah. SMAP drying is fastest when surface soil moisture levels are high, potential evaporation is high, and when vegetation cover is low. Soil texture plays a minor role in SMAP drying rates. Noah simulations show similar responses to soil moisture and potential evaporation, but vegetation has a minimal effect and soil texture has a much larger effect compared to SMAP. When drying rates are normalized by potential evaporation, SMAP observations and Noah simulations both show that increases in vegetation cover lead to decreases in evaporative efficiency from the surface soil. However, the magnitude of this effect simulated by Noah is much weaker than that determined from SMAP observations.


Citation: Shellito, P. J. and Small, E. E.: Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-338, in review, 2017.
Peter J. Shellito and Eric E. Small
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
 
RC1: 'Review of Shellito and Small', Anonymous Referee #1, 22 Aug 2017 Printer-friendly Version 
 
RC2: 'Review of "Controls on surface soil drying rates observed by SMAP and simulated by the Noah land surface model"', Anonymous Referee #2, 09 Sep 2017 Printer-friendly Version 
 
AC1: 'Final Author Comments', Peter Shellito, 16 Oct 2017 Printer-friendly Version Supplement 
Peter J. Shellito and Eric E. Small
Peter J. Shellito and Eric E. Small

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