Five important factors closely related to the ABL circulation, namely, spatio-temporal variability of the ABL depths, growth rate of the ABL depths, entrainment zone thickness, and near-surface temperature fields including resultant UHII were considered to infer the urban-rural contrasts. The mean NBL depth over the urban area was on average 63?m (45 % ) higher than its adjacent sub-urban area which was, on occasion, as much as (74?m) 58 % higher mainly due to the effect of UHII. Daytime well-mixed convective boundary layer and associated strong turbulent mixing near its top over the urban area showed higher entrainment zone thickness (326?m) than over sub-urban (234?m) and rural (200?m) areas. Temperature growth rates during sunrise increased up to more than 3?¡ãC?h?1 over the sub-urban area while over the urban region it was 2.5?¡ãC?h?1 or even less. The ABL depths over the urban site decayed more slowly (500?m?h?1) than over the sub-urban area (600?m?h?1) during the late afternoon transition period suggesting an impact of the UHII on the ABL dynamics over the urban area.
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