Slope and free air temperature in the Inn valley

Abstract

Hourly screen temperatures were collected over a four-year period for six stations from the Inn valley floor (580 masl) up the “Nordketten” slope toHafelekar (2260 masl). In this paper, we develope methods for correcting the observed screen temperatures, converting them into temperatures of the “free” valley atmosphere. Because of the combined effects of the screen and the slope layer, slope temperatures are, on average, too cold at night and too warm in the daytime. A correction function modelled after the daily march of solar radiation works well for all stations except theHungerburg. Temperatures there are, on average, up to 2.5°C too cold on clear nights, compared to the valley atmosphere, and too warm by up to 1.8°C in the daytime. A modified correction function was derived for the Hungerburg site. The suitability of the correction functions is checked by various, mostly indirect methods, the most important of which utilizes statistics of the daily range of temperature. As a final, integral check on our correction scheme, we compute vertical averages of these daily ranges, obtaining excellent agreement with mean daily ranges derived barometrically from hourly pressure recordings atInnsbruck andHafelekar.