Long-term variability of cloud cover in Poland (1971–2020)

2022 ◽  
pp. 106028
Author(s):  
Dorota Matuszko ◽  
Krzysztof Bartoszek ◽  
Jakub Soroka
Keyword(s):  
Cloud Cover

scholarly journals Cloud Cover and Aurora Contamination at Dome A in 2017 from KLCAM

2020 ◽  
Author(s):  
Xu Yang ◽  
Zhaohui Shang ◽  
Keliang Hu ◽  
Yi Hu ◽  
Bin Ma ◽  
...  
Keyword(s):  
Cloud Cover ◽  
Emission Lines ◽  
Austral Winter ◽  
Site Testing ◽  
Dome A ◽  
Astronomical Observations ◽  
Auroral Emission ◽  
Long Term Monitoring ◽  
Term Monitoring

Abstract Dome A in Antarctica has many characteristics that make it an excellent site for astronomical observations, from the optical to the terahertz. Quantitative site testing is still needed to confirm the site’s properties. In this paper, we present a statistical analysis of cloud cover and aurora contamination from the Kunlun Cloud and Aurora Monitor (KLCAM). KLCAM is an automatic, unattended all-sky camera aiming for long-term monitoring of the usable observing time and optical sky background at Dome A. It was installed at Dome A in January 2017, worked through the austral winter, and collected over 47,000 images over 490 days. A semi-quantitative visual data analysis of cloud cover and auroral contamination was carried out by five individuals. The analysis shows that the night sky was free of clouds for 83 per cent of the time, which ranks Dome A highly in a comparison with other observatory sites. Although aurorae were detected somewhere on an image for nearly 45 per cent of the time, the chance of a point on the sky being affected by an aurora is small. The strongest auroral emission lines can be filtered out with customized filters.

The use of artificial neural networks in the problem of classifying cloud types in wide-angle images of the visible hemisphere of the sky.

2021 ◽  
Author(s):  
Nikita Veremev
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Cloud Cover ◽  
Human Factor ◽  
Wide Angle ◽  
Reliable Determination ◽  
Air Masses ◽  
Key Aspects

<p>Within the framework of meteorology and oceanology, the importance of the cloud mass and the type of clouds cannot be underestimated. When describing and studying weather, precipitation and the movement of air masses over the ocean, the amount and type of clouds determines the flows of precipitation, their intensity, helps to predict the weather and the content of various impurities in the air, which makes the study of the properties of cloud cover one of the key aspects of meteorological and oceanological research.</p><p>The types of clouds are determined by the specialist, visually comparing the picture of the sky over the ocean with the guideline documents, the use of which reduces the possibility of the human factor affecting the determination of these parameters.</p><p>For an accurate study, study of the dynamics and dependence of climatic models on the conditions of cloud types, long-term measurements of the same type and the continuity of their methods are required. However, all these data are very unevenly distributed over the Earth's surface, and the number of ship observations is greatly reduced.</p><p>Thus, taking into account the importance of reliable determination of data related to cloudiness and the problems of their accuracy, the relevance and need to automate the determination of cloud types are obvious.</p><p>As a result of the work, an algorithm was obtained that allows classifying cloud types based on photographs taken during long-term sea expeditions.</p>

scholarly journals Climatological Features of the Weakly and Very Stably Stratified Nocturnal Boundary Layers. Part II: Regime Occupation and Transition Statistics and the Influence of External Drivers

2019 ◽  
Vol 76 (11) ◽  
pp. 3485-3504 ◽  
Author(s):  
Carsten Abraham ◽  
Adam H. Monahan
Keyword(s):  
Complex Terrain ◽  
Cloud Cover ◽  
Companion Paper ◽  
Statistical Features ◽  
Clear Sky ◽  
Cloud Coverage ◽  
Weakly Stable ◽  
Sky Conditions ◽  
Regime Transitions

Abstract In a companion paper hidden Markov model (HMM) analyses have been conducted to classify the nocturnal stably stratified boundary layer (SBL) into weakly stable (wSBL) and very stable (vSBL) conditions at different tower sites on the basis of long-term Reynolds-averaged mean data. The resulting HMM regime sequences allow analysis of long-term (climatological) SBL regime statistics. In particular, statistical features of very persistent wSBL and vSBL nights, in which a single regime lasts for the entire night, are contrasted with those of nights with SBL regime transitions. The occurrence of very persistent nights is seasonally dependent and more likely in homogeneous surroundings than in regions with complex terrain. When transitions occur, their timing is not seasonally dependent, but transitions are enhanced close to sunset (for land-based sites). The regime event durations depict remarkably similar distributions across all stations with peaks in transition likelihood approximately 1–2 h after a preceding transition. At Cabauw in the Netherlands, very persistent wSBL and vSBL nights are usually accompanied by overcast conditions with strong geostrophic winds Ugeo or clear-sky conditions with weak Ugeo, respectively. In contrast, SBL regime transitions can neither be linked to magnitudes in Ugeo and cloud coverage nor to specific tendencies in Ugeo. However, regime transitions can be initiated by changes in low-level cloud cover.

scholarly journals Variability and trend of diurnal temperature range in China and their relationship to total cloud cover and sunshine duration

2013 ◽  
Vol 31 (5) ◽  
pp. 795-804 ◽  
Author(s):  
X. Xia
Keyword(s):  
Diurnal Temperature Range ◽  
Cloud Cover ◽  
Sunshine Duration ◽  
Radiative Effect ◽  
Total Cloud Cover ◽  
Diurnal Temperature ◽  
Temperature Range ◽  
Clear Sky ◽  
Sky Conditions

Abstract. This study aims to investigate the effect of total cloud cover (TCC) and sunshine duration (SSD) in the variation of diurnal temperature range (DTR) in China during 1954–2009. As expected, the inter-annual variation of DTR was mainly determined by TCC. Analysis of trends of 30-year moving windows of DTR and TCC time series showed that TCC changes could account for that of DTR in some cases. However, TCC decreased during 1954–2009, which did not support DTR reduction across China. DTRs under sky conditions such as clear, cloudy and overcast showed nearly the same decreasing rate that completely accounted for the overall DTR reduction. Nevertheless, correlation between SSD and DTR was weak and not significant under clear sky conditions in which aerosol direct radiative effect should be dominant. Furthermore, 30–60% of DTR reduction was associated with DTR decrease under overcast conditions in south China. This implies that aerosol direct radiative effect appears not to be one of the main factors determining long-term changes in DTR in China.

scholarly journals National Climate Observing System of Switzerland (GCOS Switzerland)

2011 ◽  
Vol 6 (1) ◽  
pp. 95-102 ◽  
Author(s):  
G. Seiz ◽  
N. Foppa
Keyword(s):  
Land Surface ◽  
Cloud Cover ◽  
Global Climate ◽  
Biological Properties ◽  
Data Series ◽  
Climatological Data ◽  
Mountainous Regions ◽  
The North ◽  
International Data

Abstract. In recent decades, the global observation of climate and climate change has become increasingly important. The Global Climate Observing System (GCOS) established in 1992 addresses the entire climate system including physical, chemical and biological properties of atmosphere, ocean and land surface. This paper describes the GCOS implementation in Switzerland and highlights some major achievements over the last few years. The Swiss GCOS Office was established at the Federal Office of Meteorology and Climatology MeteoSwiss in February 2006, to coordinate all climate-relevant measurements in Switzerland. The first-ever inventory of the country's long-term climatological data series and international data centres, including an assessment of their future prospects, was compiled in 2007. The National Climate Observing System of Switzerland (GCOS Switzerland) includes long-term climatological data series in the atmosphere and terrestrial domains, international data and calibration centres, satellite-based products and support of climate observations in developing countries. A major milestone in the surface-based atmospheric observations was the definition of the Swiss National Basic Climatological Network (NBCN), consisting of 29 stations of greatest climatological importance. The NBCN was further densified for precipitation with 46 additional daily precipitation stations (NBCN-P). Analysis of the homogenized timeseries of the average temperature in Switzerland shows a total warming of +1.6 °C from 1864 to 2010. In the terrestrial domain, substantial advances were made in all three subdomains hydrosphere, cryosphere and biosphere. As example for the use of satellite data within GCOS Switzerland, the 10-yr MODIS monthly mean cloud fraction climatology over Switzerland from March 2000 to February 2010 is presented, which illustrates the differences in cloud cover between mountainous regions and flatland regions in winter, as well as the north-south gradient in cloud cover over Switzerland in summer.

scholarly journals A twenty-year study on natural and manmade global interannual fluctuations of cirrus cloud cover

2007 ◽  
Vol 7 (1) ◽  
pp. 93-126 ◽  
Author(s):  
K. Eleftheratos ◽  
C. S. Zerefos ◽  
P. Zanis ◽  
D. S. Balis ◽  
G. Tselioudis ◽  
...  
Keyword(s):  
Relative Humidity ◽  
North Atlantic ◽  
Annual Cycle ◽  
Cloud Cover ◽  
Cirrus Cloud ◽  
The North ◽  
Long Term Trends ◽  
The North Atlantic ◽  
The Tropics

Abstract. The seasonal variability and the interannual variance explained by ENSO and NAO to cirrus cloud cover (CCC) are examined during the twenty-year period 1984–2004. CCC was found to be significantly correlated with vertical velocities and relative humidity from ECMWF/ERA40 in the tropics (correlations up to –0.7 and +0.7 at some locations, respectively) suggesting that variations in large-scale vertical winds and relative humidity fields can be the origin of up to half of the local variability in CCC over these regions. These correlations reflect mostly the seasonal cycle. Although the annual cycle is dominant in all latitudes and longitudes, peaking over the tropics and subtropics, its amplitude can be exceeded during strong El Nino/La Nina events. Over the eastern tropical Pacific Ocean the interannual variance of CCC which can be explained by ENSO is about 6.8% and it is ~2.3 times larger than the amplitude of the annual cycle. Natural long-term trends in the tropics are generally small (about –0.3% cloud cover per decade) and possible manmade trends in those regions are also small. The contributions of NAO and QBO to the variance of CCC in the tropics are also small. In the northern mid–latitudes, on the other hand, the effect of NAO is more significant and can be very important regionally. Over northern Europe and the eastern part of the North Atlantic Flight Corridor (NAFC) there is a small positive correlation between CCC and NAO index during the wintertime of about 0.3. In this region, the interannual variance of CCC explained by NAO is 2.6% and the amplitude of the annual cycle is 3.1%. Long-term trends over this region are about +1.6% cloud cover per decade and compare well with the observed manmade trends over congested air traffic regions in Europe and the North Atlantic as have been evidenced from earlier findings.

Modelling of real solar radiation spatial distribution as a tool for solar energy cadastre in the cities

2017 ◽  
Vol 29 (2) ◽  
pp. 204-215 ◽  
Author(s):  
Małgorzata Pietras-Szewczyk ◽  
Leszek Szewczyk
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Cloud Cover ◽  
Significant Variable ◽  
State Security ◽  
Radiation Distribution ◽  
Linke Turbidity Factor ◽  
Gis Software ◽  
The City

The increasing needs of energy and decreasing traditional energy sources are becoming one of the biggest issues of our civilization. The provision of stable energy supply is a matter of state security. The energy consumption keeps growing especially in big cities. Therefore, it became reasonable to produce energy directly in cities. To optimize the use of the solar energy in the city areas, a fundamental issue is to find and estimate the amount of solar radiations at a specified location by using available tools and data. The main goal of this work is to demonstrate the potential of the r.sun model, a component of GRASS software, in calculating real solar radiation for the selected location. The work starts with demonstrating the effect of cloud cover for the amount of solar radiation reaching the Earth’s surface and the usage of GIS software and Ogimet website in the spatial analysis of real solar radiation distribution. For this purpose, data concerning cloud cover for selected locations were analysed. The study is based on the synoptic data obtained from Ogimet. Average daily cloud cover totals and long-term values were calculated. Apart from the cloud cover data, a significant variable, the Linke turbidity factor, describing the weakening of solar radiation due to the presence of aerosols and water vapour in the atmosphere, was taken into consideration. The obtained results were used to develop a map of real solar radiation distribution for a part of Wrocław. The results obtained by that model with the acquired data by the local meteorological station show compatibility.

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