A comparison of sunshine duration records from the Campbell-Stokes sunshine recorder and CSD3 sunshine duration sensor

The purpose of this paper is to compare daily sunshine duration data measured using a Campbell-Stokes sunshine recorder (CS) and a CSD3 sunshine duration sensor (AUTO) as well as to attempt to explain discrepancies between the two data sets. The paper is based on heliographic data and cloudiness observations for 2007–2012. All the data come from the research station of the Jagiellonian University located in Krakow, Poland. Both instruments tend to produce similar sunshine duration data; however, the electronic sensor tends to show more sunshine duration than the CS. The difference may amount to several hours a day, especially on days with maximum solar radiation. The CSD3 sensor is twice as sensitive as the CS and reacts quickly to solar radiation. This is especially true for the first hour following sunrise, the last hour before sunset and when the Sun’s disc becomes visible for short periods of time due to changes in cloudiness. However, there are days when the CSD3 registers less sunshine duration (up to an hour) than the CS. This happens with \mathit{Cumulus} clouds in the sky, which tend to pass the Sun’s disc very quickly. The CSD3 sensor does not register sunshine in the presence of thick \mathit{Altostratus} and \mathit{Cirrostratus} clouds due to the relative lack of direct radiation. The sunshine recorder, on the other hand, registers this low level of sunshine

Climate change in Krakow and adaptation to it in the context of urban planning

Na podstawie danych klimatologicznych z lat 1901-2020 ze stacji naukowej Zakładu Klimatologii IGiGP UJ w Krakowie dokonano charakterystyki przebiegu wieloletniego wybranych elementów klimatu Krakowa i wskazano rolę miejscowych planów zagospodarowania przestrzennego w aspekcie minimalizowania skutków miejskiej wyspy ciepła i globalnego ocieplenia.Based on climatological data from 1901-2020 from the Research Station of the Department of Climatology of the Institute of Geography and Spatial Management of the Jagiellonian University in Krakow, the multi-year course of selected elements of Krakow climate was characterised and the role of local spatial development plans was indicated in terms of minimising the effects of the urban heat island and global warming

Long-term variability of the low-level cloud base height in Poland

The aim of the study is to characterize the long-term variability of the low-level cloud base heights (CBH) in Poland in the years 1971-2020. Data were used from six weather stations belonging to the Institute of Meteorology and Water Management-the National Research Institute (IMWM-NRI), where CBH was first measured using the IWO device and, since the 1990s, using a ceilometer. The analysis allowed for data from eight observation periods (0000, 0300, 0600, 0900, 1200, 1500, 1800, 2100 UTC), which referred to several height ranges (between the ground surface and 2500 m a.s.l.). In the ana-lysed multiyear period, in the cool half of the year, the height of theCumulonimbuscloud bases increased significantly, that is, the number of cases increased at a height of>1000 m and, in the warm half of the year, at>1500 m. In recent years, the number of cases of the Cumulus cloud with abase at a height between 300 and 999 m has clearly decreased, while it has increased at a height of 1000-1499 m (in October-March) and 1500-1999 m(April-September). A similar increase in CBH was found in the case of the Stratocumulus cloud (their greater share between 1500 and 2499 m). It was only in the case of the Stratus cloud that a lowering of the cloud base was noticed, possibly owing to the imperfect measurement of he fractus species.The positive upward trend inthe base heigh to most low-level clouds can be explained by a statistically significant increase in temperature and a decrease in relative air humidity in the lower troposphere

The long-term course of the annual total sunshine duration in Europe and changes in the phases of the thermohaline circulation in the North Atlantic (1901-2018)

The current study was based on sunshine duration data from 13 European stations during 1901–2018. It was found that the variability in the annual total sunshine duration (SD) over Europe is related to the variability in the component of the surface thermohaline circulation in the North Atlantic (NA THC). Positive NA THC phases (the condition of the ‘warm’ North Atlantic) correspond to the periods of increased SD (brightening), while negative phases correspond to the periods of decreased SD (dimming). These relationships remain stable and statistically significant. The mechanism of these relationships is based on the influence of weakened or enhanced heat flow from the ocean to the atmosphere on the course of the mid-tropospheric circulation processes. In periods of positive thermohaline circulation in the North Atlantic (NA THC) phases, the share of long waves (macrotype W according to the Wangengejm–Girs classification) increases, with the occurrence of which the frequency of anticyclonic weather over Europe increases, whereas in the periods of negative NA THC phases, the share of shorter waves (macrotypes E and C) increases, with the occurrence of which the frequency of cyclonic (frontal) weather over Europe increases. It is characterised by increased layer cloud cover, limiting the SD. Thus, along with changes in the thermal condition of the North Atlantic, the structure of cloud cover over Europe changes and becomes a factor regulating long-term changes in the annual total SD

The increase in the proportion of impervious surfaces and changes in air temperature, relative humidity, and cloud cover in Poland

The aim of the study is to characterise the changes in the proportion of impervious surfaces (ISs) in Poland and their impact on changes in temperature, air humidity, and cloud cover. The results of satellite image classification from 1990, 2000, 2010 and 2020, as well as meteorological data from the period 1981–2020 for the warm half of the year, were used. An analysis was performed making it possible to compare the changes in the proportion of ISs in 3 decades, i.e. 1991–2000, 2001–2010 and 2011–2020. In Poland, in the years 1991–2020, the total area of ISs increased by approximately 30%. At the same time, statistically significant positive trends in maximum temperature are visible throughout Poland, ranging from $0.48^{\circ}C$ per 10 years to $>0.90^{\circ}C$ per 10 years. Trends in the magnitude of low-level cloud cover are negative throughout Poland and range from −2.7% to −2.3% per 10 years. The frequency of stratiform clouds is decreasing, while that of mid-level Cirrus and Cumulus clouds is increasing. The results show a relationship between the increase in ISs in Polish cities and changes in meteorological elements in their area and in the immediate vicinity, which were most pronounced in the first decade of the 21st century

Sunshine duration in the European Arctic and Greenland based on the data from selected stations in the polar regions

W pracy przedstawiono zmienność usłonecznienia w rejonach polarnych na podstawie danych z wybranych stacji Arktyki Europejskiej i Grenlandii. Do ogólnej charakterystyki wykorzystano średnie sumy miesięczne ze standardowego 30-lecia (1961-1990) z 15 stacji położonych na północ od koła polarnego, natomiast szczegółową analizę wykonano na podstawie danych z Polskiej Stacji Polarnej w Hornsundzie (lata 1979-2014) oraz ze stacji: Bjornoya (lata 1961-2004), Tromso (lata 1961-2014), Bodo VI (lata 1961-2005) i Barentsburg (lata 1961-2014). W strefie polarnej duży wpływ na wartości usłonecznienia oprócz czynników astronomicznych i cyrkulacyjnych mają warunki lokalne. Największe sumy roczne usłonecznienia występują na Grenlandii (Danmarkshavn – 1967 godzin) znajdującej się w strefie oddziaływania stałego wyżu, natomiast najmniejsze na stacji Bjornoya (595 godzin), co związane jest z położeniem wyspy na szlaku niżów i związanych z nimi frontów atmosferycznych powodujących duże zachmurzenie. Przebieg wieloletni usłonecznienia w rejonach na północ od koła polarnego w niewielkim stopniu nawiązuje do tendencji obserwowanych na stacjach w pozostałej części Europy – zmniejszenia liczby godzin ze słońcem w latach pięćdziesiątych do osiemdziesiątych XX wieku, a następnie wzrostu w ostatnich dwóch dekadach XX wieku.The aim of this study is to characterize sunshine duration in the polar regions based on the data from selected stations located north of the European Arctic and Greenland. Mean monthly totals of sunshine duration from standard 30-year period (1961-1990) from 15 stations located north of the Arctic Circle were used for general characteristics, and a detailed analysis was performed based on the data from Polish Polar Station in Hornsund (1961-2014) and from the stations: Bjornoya (1961-2004), Tromso (1961-2014), Bodo VI (1961-2005) and Barentsburg (1961-2014). In the polar regions, local conditions in addition to astronomical and circulation factors have influence on values of sunshine duration. Analysis of the variability of sunshine duration in the polar regions confirmed large regional differences of this element at the analyzed stations of European Arctic and Greenland. In the polar regions, apart from the astronomical factors (polar day and night), local conditions have a big impact on sunshine duration values (orography – horizon covering, the low position of the solar disc and methodical aspect of measurements – e.g. changing the traditional instrument for the automatic one). The conducted analysis showed that the course of annual sunshine duration depends mainly on the station location (latitude and cloudiness influenced by orographic and circulation factors). Similar annual course with a maximum in May occurs in stations located on similar latitudes (Polish Polar Station in Hornsund, Bjornoya, Thule and Danmarkshavn). However, the least sunshine is present Aat Bjornoya station (595 hours) due to heavy cloudiness associated with predominance of lows, and the largest in Danmarkshavn (1967), located within Greenland High. Based on the conducted analysis and cited literature it can be concluded that the long-term course of sunshine duration in the polar regions to a small extent refers to the trend observed in European stations. This fact can suggest anthropogenic causes of global dimming and brightening. Sunshine duration series from Barentsburg shows a statistically significant negative trend, while in Krakow, an increase of sunshine is observed, which is in line with trends in the rest of Europe