Honzakova, Katerina. 2017. Small-scale variations of climate change in mountainous-forested terrain; A study from the H.J. Andrews Long Term Ecological Research site, Oregon, USA. Bayreuth: University of Bayreuth. 47 p. MS Thesis.
The influence of topography on regional climate change remains a poorly understood phenomenon. In this thesis, long-term temperature records from the H.J. Andrews Experimental Forest (HJA), Oregon, USA and six stations from the Snotel network at a distance 20 - 50 km from the HJA were analyzed. Temperature patterns of the study area were investigated, with a focus on comparing valley and ridge stations. In particular, trends of the last day of frost, length of the vegetation period, temperature and the annual number of cyclonic, anti-cyclonic and zonal winds were explored.
Additionally, the effect of homogenization of the temperature time series prior to analysis was considered. During the study period (1958 - 2011), the valley stations considered showed more consistent trends of an earlier last day of frost and warming daily minimum temperatures compared to stations at higher elevations. Changes in synoptic forcing towards more cyclonic activity and hence less cold air pooling in spring could serve as a reasonable explanation of these results. Data homogenization was found to considerably affect the temperature trends obtained. Further research and more data are needed.