<abstract xmlns="http://www.w3.org/1999/xhtml">The cities of Ljubljana, Trieste and Zagreb are proximate in terms of distance but differ in terms of geographical and climatic conditions. Continuous meteorological measurements in these cities began in the mid-19th century. The 100-year trends of changes in mean annual and seasonal air temperatures for these cities are presented here, evaluating the differences between them which result from their different geographical and climatic positions. Differences in trends between Ljubljana and Zagreb that result from different measurement histories and the impact of urban climate are also presented: the impact of city growth on air temperatures in Ljubljana after 1950 was not completely eliminated in the process of data homogenization. The lowest air warming trends occur in the maritime climate of Trieste (mean annual air temperature: + 0.8 °C × 100 yr−1), where measurements were continuously performed in the densely built-up section of the city. The strongest trends occur in Ljubljana, mainly due to city growth (mean annual air temperature: + 1.1 °C × 100 yr−1). Comparing the linear trends in Zagreb-Grič and in Ljubljana, the impact of Ljubljana's urban heat island on the 100-year warming trend was assessed at about 0.2 °C, at 0.3–0.4 °C for the trend after 1950, and if non-homogenized data are used, at about 0.5 °C.</abstract>

The cities of Ljubljana, Trieste and Zagreb are proximate in terms of distance but differ in terms of geographical and climatic conditions. Continuous meteorological measurements in these cities began in the mid-19th century. The 100-year trends of changes in mean annual and seasonal air temperatures for these cities are presented here, evaluating the differences between them which result from their different geographical and climatic positions. Differences in trends between Ljubljana and Zagreb that result from different measurement histories and the impact of urban climate are also presented: the impact of city growth on air temperatures in Ljubljana after 1950 was not completely eliminated in the process of data homogenization. The lowest air warming trends occur in the maritime climate of Trieste (mean annual air temperature: + 0.8 °C × 100 yr−1), where measurements were continuously performed in the densely built-up section of the city. The strongest trends occur in Ljubljana, mainly due to city growth (mean annual air temperature: + 1.1 °C × 100 yr−1). Comparing the linear trends in Zagreb-Grič and in Ljubljana, the impact of Ljubljana's urban heat island on the 100-year warming trend was assessed at about 0.2 °C, at 0.3–0.4 °C for the trend after 1950, and if non-homogenized data are used, at about 0.5 °C.

Long-term air temperature changes in Ljubljana (Slovenia) in comparison to Trieste (Italy) and Zagreb (Croatia)

Department of Geography, Faculty of Arts, University of Ljubljana, Ljubljana, Slovenia

Moravian Geographical Reports

This chapter is distributed under the terms of the Creative Commons Attribution 4.0 Public License.

The cities of Ljubljana, Trieste and Zagreb are proximate in terms of distance but differ in terms of geographical and climatic conditions. Continuous...

Long-term air temperature changes in Ljubljana (Slovenia) in comparison to Trieste (Italy) and Zagreb (Croatia)

Published Online: Oct 29, 2015

Page range: 17 - 26

Received: Nov 28, 2014

Accepted: Jul 17, 2015

DOI: https://doi.org/10.1515/mgr-2015-0014

Keywords
climate change in the instrumental period, long-term temperature trends, urban heat island, Ljubljana (Slovenia), Trieste (Italy), Zagreb (Croatia)

© 2015 Darko Ogrin, published by De Gruyter Open

This chapter is distributed under the terms of the Creative Commons Attribution 4.0 Public License.

Long-term air temperature changes in Ljubljana (Slovenia) in comparison to Trieste (Italy) and Zagreb (Croatia)

Published Online: Oct 29, 2015

Page range: 17 - 26

Received: Nov 28, 2014

Accepted: Jul 17, 2015

DOI: https://doi.org/10.1515/mgr-2015-0014

Keywordsclimate change in the instrumental period, long-term temperature trends, urban heat island, Ljubljana (Slovenia), Trieste (Italy), Zagreb (Croatia)

© 2015 Darko Ogrin, published by De Gruyter Open

This chapter is distributed under the terms of the Creative Commons Attribution 4.0 Public License.

Keywords
climate change in the instrumental period, long-term temperature trends, urban heat island, Ljubljana (Slovenia), Trieste (Italy), Zagreb (Croatia)