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Hemes, K. S., Eichelmann, E., Chamberlain, S. D., Knox, S. H., Oikawa, P. Y., Sturtevant, C. et al. (2018). A Unique Combination of Aerodynamic and Surface Properties Contribute to Surface Cooling in Restored Wetlands of the Sacramento‐San Joaquin Delta, California. Journal of Geophysical Research: Biogeosciences, 123, 2072-2090.
https://doi.org/10.1029/2018jg004494

has been cited by the following article:

• TITLE: Diurnal and Seasonal Trends in Aerodynamic Conductance over a Grassland Surface

  AUTHORS: Ippei Iiyama

  KEYWORDS: Friction Velocity, Monin-Obukhov Length, Sensible Heat, Universal Similarity Function

  JOURNAL NAME: Journal of Geoscience and Environment Protection, Vol.13 No.10, October 16, 2025

  ABSTRACT: The aerodynamic conductance K [m s−1] is important for quantifying thermal and hydrological environments around a land surface under possible climatic scenarios. This study aimed at clarifying diurnal and seasonal trends in K [m s−1] over a grassland surface. Measured data sets of air temperatures Ta [K] at two heights and wind speed u [m s−1] at one height were used with the equations of the wind- and temperature-profiles. K [m s−1] started increasing after sunrise, lowered steeply in late afternoon, and became stable at the daily lowest level during night, suggesting that daylength defines the time period when turbulent transport effectively occurs. The seasonal change in the diurnal pattern of K [m s−1] was characterized by the transitions of the size of K [m s−1] and the time of its daily peak. The daily maximum K [m s−1] grew from January, became the highest of more than 0.015 [m s−1] in April, and decreased through summer to winter. The time of the daily maximum K [m s−1] was shifted so that it was found around 16:00 in summer and moved forward in winter. These diurnal and seasonal features of K [m s−1] resembled those of friction velocity and u [m s−1], suggesting that aerodynamic conductance is affected primarily by wind properties. Every month, the u-K relation drew a diurnal loop with the time of day. The loop size varied seasonally in accord with the seasonality of the sizes in u [m s−1] and K [m s−1], and a value of K [m s−1] in the morning became two times larger or more than that in the evening for a given u [m s−1]. The apparent hysteretic behavior in the diurnal u-K relation was attributable to the change in the direction of the vertical gradient in air temperature during the daytime. The non-uniqueness in the diurnal u-K relation implied that atmospheric stability needs to be considered when diurnal patterns of aerodynamic conductance are evaluated.