Long‐Term Variability of Aerosol Optical Depth in the Tatra Mountain Region of Central Europe

Abstract

This paper presents the results of long‐term observations (1964–2010) of direct solar flux at two stations in the Tatra Mountains in Poland (Central Europe). The measurements obtained from a Linke‐Feussner actinometers are used to estimate broadband (0.29–2.9 μm) and wideband (0.53–0.63 μm) aerosol optical depth (BAOD and WAOD, respectively). Both BAOD and WAOD at Mount Kasprowy Wierch (1,991 m a.s.l.) and in Zakopane (851 m a.s.l.) show similar annual cycles with peaks during spring and summer. Coincidence of actinometer observation at the top of the Tatra Mountains and in Zakopane valley allows determination of AOD in the column between 851 and 1,991 m a.s.l. Annual variabilities of both BAOD and WAOD for this layer are similar to PM10 concentration measurements in Zakopane. Conversely, BAOD and WAOD obtained at both stations show opposing annual variability, which is consistent with the Aerosol Robotic Network and model results in Central Europe. Long‐term data show significant reduction of both BAOD and WAOD in Zakopane (−0.018 ± 0.003 and −0.023 ± 0.003, respectively, per decade) and lower reductions at Mt. Kasprowy Wierch (−0.005 ± 0.002 and −0.009 ± 0.002, respectively, per decade). Trends for BAOD and WAOD defined between 851 and 1,991 m a.s.l. are the same (−0.013 ± 0.004 per decade), which corresponds to the reduction of WAOD and BAOD by about 60% between 1964 and 2010. Conversely, emission data for the Zakopane region obtained from Emissions Database for Global Atmospheric Research inventories shows reduction of SO2 by a factor of 3 and of NOx and PM10 by about 40% between 1988 and 2010.

A Decade of Poland-AOD Aerosol Research Network Observations

“…For this purpose, a methodology to retrieve broadband and wideband AOD is being developed [63] within the Poland-AOD network. The results of this study show a significantly lower reduction in AOD obtained for the high mountain station (Kasprowy Wierch) in comparison to the Belsk and Zakopane sites, but also the opposite annual cycle of AOD at Mount Kaprowy Wierch to the AOD defined in the vertical column (1140 m) from Zakopane valley to Kasprowy Wierch, which is similar to the PM 10 concentration measurements in Zakopane [62]. Both can be explained by reducing anthropogenic emissions rather than natural emissions variability (e.g., volcanic).…”

“…On the other hand, the impact of aerosol on winter warming is significantly smaller due to low solar radiation flux and lower AOD and higher cloud cover than in summer. Reduction in AOD in the last decades (since 1964) is estimated from long-term direct observation of broadband and wideband solar flux at Belsk [61] and WMO stations in Zakopane [62] and Kasprowy Wierch [62,63]. For this purpose, a methodology to retrieve broadband and wideband AOD is being developed [63] within the Poland-AOD network.…”

A large reduction of direct aerosol cooling over Poland in the last decades

“…Markowicz et al . (2019) present similar solar radiation measurements in the Tatra Mountains that show significantly smaller but still negative trends. For instance, in Zakopane (851 m a.s.l.)…”

“…Similar variability is reported by Markowicz et al . (2019) in the Tatra Mountains (Poland). The 580 nm (530–630 nm) AOD trend per decade (1964–2010) is −0.023 ± 0.003 at the lower station (851 m a.s.l.)…”

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

“…Magnitude and variability of mean decadal PM 2.5 atmospheric concentration mostly declines between decade 7th and 17th (Figure 6), which can be attributed to a reduction in emissions from heating systems between winter and summer [35]. Over urban areas in Poland, the mean PM 2.5 concentration was significantly lower (−20%) in 2020 as compared to the 10-year average, whereas in 2019 this difference was less noticeable (−8%).…”