Hydrology, Cryosphere & Earth Surface Editors' Highlights

Wet Soils Elevate Nighttime Temperatures

Soil moisture can elevate overnight temperatures, offsetting daytime cooling, especially over areas of strong land-atmosphere interactions.

Source: Journal of Advances in Modeling Earth Systems (JAMES)


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Using a conceptual model of the surface energy budget, Cheruy et al. [2017] demonstrate a noteworthy negative nocturnal link between soil moisture and temperature that is particularly strong in so-called “hot-spot” regions of land-atmosphere coupling. The negative link operates through the effect of water on the thermal inertia of the soil: dry soils can fluctuate in temperature much more readily than wet soils. Monsoon regions and transition zones between arid and humid climates have large day-to-day variability of the thermal inertia, which mainly affects variability of nighttime minimum temperatures. Here, positive soil-moisture anomalies induce cooler daytime temperatures through increased evaporative cooling, a well-known phenomenon. However, at night the higher heat capacity and thermal inertia of the wetter soil strongly prevents nocturnal cooling. The opposite situation arises for anomalously dry soils: increased daytime maximum temperatures but lower nighttime minimum temperatures.

Citation: Cheruy, F., Dufresne, J. L., Aït Mesbah, S., Grandpeix, J. Y., & Wang, F. [2017]. Role of soil thermal inertia in surface temperature and soil moisture-temperature feedback. Journal of Advances in Modeling Earth Systems, 9. https://doi.org/10.1002/2017MS001036

—Paul A. Dirmeyer, Editor, JAMES

Correction, 22 January 2018: The word “feedback” has been changed to “link” because the mechanism described does not represent a primary closed loop, in the standard sense of feedback processes, but rather a coupled process linkage.

© 2018. The authors. CC BY-NC-ND 3.0