Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers

The extremes of month-specific spatial temperature differences were studied for a first time in the high-latitude city of Lahti and its surroundings in southern Finland. During the 2-year observation period (6/14–5/16), the largest momentary temperature difference, 11.1 °C, was detected in February,...

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Main Author: Juuso Suomi
Format: Article
Language:English
Published: Elsevier 2018-03-01
Series:Weather and Climate Extremes
Online Access:http://www.sciencedirect.com/science/article/pii/S2212094717300828
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author Juuso Suomi
author_facet Juuso Suomi
author_sort Juuso Suomi
collection DOAJ
description The extremes of month-specific spatial temperature differences were studied for a first time in the high-latitude city of Lahti and its surroundings in southern Finland. During the 2-year observation period (6/14–5/16), the largest momentary temperature difference, 11.1 °C, was detected in February, and the smallest, 6.2 °C, in April. The impacts of various environmental factors during the extreme situations were estimated by site-specific analysis of the warmest and coldest observation sites and a stepwise multiple linear regression model including all the 8 observation sites. The extreme temperature differences were characterised by inversions especially in winter and spring, the warmest site being the hill-top location in Kivistönmäki. In summer the role of urban heating was more apparent, and the temperature was the highest in the relatively low-lying city centre. In autumn the heating impact of the relatively warm Lake Vesijärvi caused the largest temperature differences with harbour as the warmest site. The weather during all of the momentary extreme situations was calm and in the majority of the situations also clear. The impact of cloud cover was less critical than that of wind speed in reducing spatial temperature differences. The momentary extreme situations existed at night or at dawn, with one exception: only in January, during the cold weather period dominated by high pressure, the delayed break of inversion in the vicinity of Lake Vesijärvi caused the extreme temperature difference to exist in the afternoon, reflecting for its part the substantial stabilising impact of seasonal ice cover on Lake Vesijärvi. Keywords: Extreme temperature difference, Land use, Topography, Urban heat island, Water body, Seasonality
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spelling doaj.art-1b4d6a80684f451bb0df4fdfdb8d1af72022-12-21T18:48:18ZengElsevierWeather and Climate Extremes2212-09472018-03-01192028Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental driversJuuso Suomi0Department of Geography and Geology, University of Turku, FI-20014, Turku, FinlandThe extremes of month-specific spatial temperature differences were studied for a first time in the high-latitude city of Lahti and its surroundings in southern Finland. During the 2-year observation period (6/14–5/16), the largest momentary temperature difference, 11.1 °C, was detected in February, and the smallest, 6.2 °C, in April. The impacts of various environmental factors during the extreme situations were estimated by site-specific analysis of the warmest and coldest observation sites and a stepwise multiple linear regression model including all the 8 observation sites. The extreme temperature differences were characterised by inversions especially in winter and spring, the warmest site being the hill-top location in Kivistönmäki. In summer the role of urban heating was more apparent, and the temperature was the highest in the relatively low-lying city centre. In autumn the heating impact of the relatively warm Lake Vesijärvi caused the largest temperature differences with harbour as the warmest site. The weather during all of the momentary extreme situations was calm and in the majority of the situations also clear. The impact of cloud cover was less critical than that of wind speed in reducing spatial temperature differences. The momentary extreme situations existed at night or at dawn, with one exception: only in January, during the cold weather period dominated by high pressure, the delayed break of inversion in the vicinity of Lake Vesijärvi caused the extreme temperature difference to exist in the afternoon, reflecting for its part the substantial stabilising impact of seasonal ice cover on Lake Vesijärvi. Keywords: Extreme temperature difference, Land use, Topography, Urban heat island, Water body, Seasonalityhttp://www.sciencedirect.com/science/article/pii/S2212094717300828
spellingShingle Juuso Suomi
Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers
Weather and Climate Extremes
title Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers
title_full Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers
title_fullStr Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers
title_full_unstemmed Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers
title_short Extreme temperature differences in the city of Lahti, southern Finland: Intensity, seasonality and environmental drivers
title_sort extreme temperature differences in the city of lahti southern finland intensity seasonality and environmental drivers
url http://www.sciencedirect.com/science/article/pii/S2212094717300828
work_keys_str_mv AT juusosuomi extremetemperaturedifferencesinthecityoflahtisouthernfinlandintensityseasonalityandenvironmentaldrivers