Evolution of nocturnal temperature inversions - A numerical study

Ragothaman, S. and Narasimha, R, and Vasudeva Murthy, A.S. (2002) Evolution of nocturnal temperature inversions - A numerical study. Il nuovo cimento C, 25 (2). pp. 147-163. ISSN 1826-9885

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A series of numerical simulations using a one-dimensional energy balance model suggest that both the depth and the intensity of the nocturnal temperature inversion depend on surface emissivity �g and a ground cooling rate parameter β (which inthe model is a surrogate for the inverse square root of the soil thermal diffusivity), especially under calm conditions. It is found that, after a transient that may last a few hours after nominal sunset, both depth and intensity follow the classical parabolic growth law, but only under calm conditions. If the ground cools faster the transient for the inversion depth is longer and the inversion deeper. If the surface is radiatively darker, the transient is again longer but the inversion depth is lower. The temperature at the top of the inversion is not strongly influenced by �g or β, but, depending on whether the reference is taken at the surface or at screen height, the intensity of the inversion decreases (or increases) with a drop in �g; it also increases with increase in ground cooling rate but with either choice of reference temperature. With wind, the inversion may be deeper during the transient than under calm conditions, but eventually becomes both shallower and weaker, and may disappear altogether at high winds. The effect of wind is found to be negligible whenthe frictionv elocity is less than0.2 ms −1. Comparison with observations shows general qualitative agreement, but also suggests that the highly variable results reported inthe literature onin version parameters may be due to site-dependent surface characteristics whose effects, till now ignored, need explicit attentionin future field observations and models.

Item Type: Article
Uncontrolled Keywords: Boundary layer structure and processes ; Reactive, radiative, or nonequilibrium flows
Subjects: 500 Scienze naturali e Matematica > 550 Scienze della Terra > 551 Geologia, Idrologia, Meteorologia
Depositing User: Marina Spanti
Date Deposited: 12 Mar 2020 10:44
Last Modified: 12 Mar 2020 10:44
URI: http://eprints.bice.rm.cnr.it/id/eprint/14771

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