Screen level temperature increase due to higher atmospheric carbon dioxide in calm and windy nights revisited

Abstract

[1] Long-term surface observations over land have shown temperature increases during the last century, especially during nighttime. Observations analyzed by Parker (2004) show similar long-term trends for calm and windy conditions at night, and on basis of this it was suggested that the possible effect of urban heat effects on long-term temperature trends are small. On the other hand, a simplified analytic model study by Pielke and Matsui (2005) (hereinafter referred to as PM05) suggests that at night the resultant long-term temperature trends over land should depend on height and strongly on wind speed (mostly due to alterations in the rate of nocturnal cooling in the stable boundary layer (SBL)). In this paper we expand the PM05 study by using a validated atmospheric boundary layer model with elaborated atmospheric physics compared to PM05, in order to explore the response of the SBL over land to a change in radiative forcing. We find that the screen level temperature response is surprisingly constant for a rather broad range of both geostrophic wind speed (5–15 m s−1) and 10 m wind (2–4.0 m s−1). This is mostly due to land surface-vegetation-atmosphere feedbacks taken into account in the present study which were not considered by PM05.