Sunshine duration and its variability in the main ridge of the Karkonosze Mountains in relation to with atmospheric circulation

Abstract

Sunshine duration analysis was based on a series of measurements spanning the period from 1901 to 2014 for Śnieżka (1603 m a.s.l.) and from 1961 to 2000 for Szrenica (1362 m a.s.l.). The average annual sunshine duration (SD) on Śnieżka is 1423.0 h, which is among the lowest values in Poland. On average, the main ridge of the Karkonosze range receives 31% of potential sunshine duration in annual terms: from 25% in December to 36% in August and May. The changes in sunshine duration recorded on Śnieżka point to the existence of two cycles: a short one of approx. 2-4 years and a long one of approx. 60 years. The former most probably reflects the rhythm of atmospheric circulation in the North Atlantic (North Atlantic Oscillation), while the latter reflects the impact of ocean circulation associated with the AMO (Atlantic Multidecadal Oscillation) mechanism. Annual SD totals for the years 1901-2014 exhibit a slight trend to an increase of approx. 2.5 h/10 years, and the rate of increase during the winter quarter is many times higher than during the other seasons. Average monthly sunshine duration differences between Śnieżka and Szrenica are positive for all months of the year with the average monthly difference being 10 to 11 h. This means that the average radiation conditions on Śnieżka are more favourable than the main ridge of the Karkonosze range, which lies at an altitude 200 to 250 m lower. Average daily sunshine durations recorded on Śnieżka are only shorter than those on Szrenica for macro-types of atmospheric circulation with advection from the south.

Trends in sunshine duration in Poland (1971–2018)

“…As stated at the beginning of the article, temporal and spatial trends in SD are explained in climatological literature by the variability of atmospheric circulation (e.g., Degirmendžić, 2004; Lewik et al ., 2010; Urban et al ., 2018), changes in cloud cover (e.g., Morawska‐Horawska, 1985; Lewik et al ., 2010), and changes in the transparency of the atmosphere, that is, the amount of aerosols in the air (e.g., Wild, 2009; Folini and Wild, 2011; Wild, 2012; Wang et al ., 2013; Vetter and Wechsung, 2015).…”

Spatiotemporal variability of sunshine duration and influential climatic factors in mainland China during 1959–2017

“…The analysis of the influential variables on SD variability indicates that Win plays a governing role in most regions of mainland China at spatial scale, and Pre serves as a complementary factor at temporal scale according to Figure 9 and Table 4. The physical cause for the decrease of SD is extraordinarily complicated, and the mainstream standpoint is that the combined effect of climate change and intensifying human activities has contributed to it (Sanchez‐Romero et al ., 2016; Fan et al ., 2018; Urban et al ., 2018). The accelerated hydrological cycle due to global warming has enhanced precipitation in most areas of China (Xue et al ., 2018), leading to the increase of the total amount of clouds and the reduction of visibility (Kawamoto, 2006), which can be considered as a direct factor related to the decrease of SD (Josefsson and Landelius, 2000).…”

Trace elements in Athyrium distentifolium from alpine vegetation in the Karkonosze, SW Poland

“…The Karkonosze is the largest mountain chain in the Sudety, SW Poland, formed by a crystalline massif reaching up to 1603 m a.s.l. (Urban et al 2017). Granites, with an admixture of crystalline schists and gneisses, form the main acidic bedrock (Mochnacka and Banaś 2000).…”