Fog climatology in Latvia

Avotniece, Zanita; Kļaviņš, Māris; Lizuma, Lita

doi:10.1007/s00704-014-1270-4

Cited by 20 publications

(20 citation statements)

References 23 publications

(44 reference statements)

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“…Akimoto and Kusaka (2015) studied the climatological characteristics of fog in Japan and the results indicated that the numbers of foggy days decreased at many of the observation sites during a 40-year period from 1966 to 2005. The decreasing trend of fog frequency was also found in Latvia across a 52-year period (Avotniece et al, 2015). Dense fog with visibility less than 400 m seems to be reduced in many parts of the world (LaDochy and Witiw, 2012).…”

Section: Discussionmentioning

confidence: 83%

“…Therefore, studies on the changes in frequency and intensity of fog caused by climate change are of high importance (Avotniece et al, 2015). During 1959-2014, a significant decreasing trend was detected in the frequency of foggy days in most regions of China, and foggy days increased firstly and then decreased continuously in some regions (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…An airport visibility assessment of fog frequency in the Central Valley of California revealed that fog occurrence had decreased substantially, and overall dense fogs with visibility of less than 1/4 mile had decreased by ∼ 50 % since the 1980s (Herckes et al, 2015). Temperature increase or vapour reduction due to urbanization, global warming followed by synoptic-scale climate change, and variation in aerosol concentration and air quality may affect the formation of fog (Shi et al, 2010;Akimoto and Kusaka, 2015;Avotniece et al, 2015). The decrease of fog in urban areas has also been reported in some cities in the United States, where it is said to reflect the reduction of particulates, the intensification of urban heat island and Pacific sea surface temperature, along with large-scale interaction of the atmosphere and the ocean (LaDochy and Witiw, 2012).…”

Section: Discussionmentioning

confidence: 99%

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Patterns and trends of high-impact weather in China during 1959–2014

Shi

Wen

Cui³

2016

Nat. Hazards Earth Syst. Sci.

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Abstract. The spatial and temporal characteristics of the frequencies of four types of high-impact weather (HIW), i.e. snowfall, thunderstorms, fog and hailstorms, were analysed in China during . Results indicate a significant decrease in the number of snowfall days, thunderstorm days and thunderstorm spells in all six regions of China, with regional decreasing rates of 0.1-3.4 days, 1.6-5.1 days and 0.23-0.77 times per decade respectively. The number of foggy days, hailstorm days and snowfall spells decreased at rates of 0.2-1.8 days, 0.1-0.7 days and 0.14-0.44 times per decade respectively in almost all regions and fog and hailstorm spells decreased at rates of 0.06-0.17 and 0.001-0.043 times per decade respectively in most regions of China. Spatially, there was more snowfall in northeastern China and western China, and more thunderstorms in southern China and southwestern China. The number of fog events was larger in some high mountain stations, eastern China and central China. Hailstorms were concentrated on QinghaiTibet Plateau. Over the past 56 years, snowfall days, thunderstorm days and thunderstorm spells decreased in most parts of China, and hailstorm days decreased in northeastern China, most parts of northern China and Tibet, southern Qinghai and western Sichuan. The spatial trends of foggy days, foggy spells, snowfall spells and hailstorm spells were not significant in most parts of China. With global warming, some types of HIW are likely to increase in their intensities, so more mitigation and adaptation strategies are still essential for local government and the public in China.

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Patterns and trends of high-impact weather in China during 1959–2014

Shi

Wen

Cui³

2016

Nat. Hazards Earth Syst. Sci.

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“…The only long term fog climatologies that have been developed recently were simply derived using interpolation techniques on observational in situ measurements for single countries [12] or the climatology was limited to single locations [13,14]. Avotniece et al [15] used a combination of in situ measurements and a geostationary satellite cloud product to derive fog frequencies. However, only seasonal average cloud products were used and the computed output was limited to Latvia.…”

Section: Introductionmentioning

confidence: 99%

A Hybrid Approach for Fog Retrieval Based on a Combination of Satellite and Ground Truth Data

2018

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Fog has a substantial influence on various ecosystems and it impacts economy, traffic systems and human life in many ways. In order to be able to deal with the large number of influence factors, a spatially explicit high-resoluted data set of fog frequency distribution is needed. In this study, a hybrid approach for fog retrieval based on Meteosat Second Generation (MSG) data and ground truth data is presented. The method is based on a random forest (RF) machine learning model that is trained with cloud base altitude (CBA) observations from Meteorological Aviation Routine Weather Reports (METAR) as well as synoptic weather observations (SYNOP). Fog is assumed where the model predicts CBA values below a dynamically derived threshold above the terrain elevation. Cross validation results show good accordance with observation data with a mean absolute error of 298 m in CBA values and an average Heidke Skill Score of 0.58 for fog occurrence. Using this technique, a 10 year fog baseline climatology with a temporal resolution of 15 min was derived for Europe for the period from 2006 to 2015. Spatial and temporal variations in fog frequency are analyzed. Highest average fog occurrences are observed in mountainous regions with maxima in spring and summer. Plains and lowlands show less overall fog occurrence but strong positive anomalies in autumn and winter.

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“…In Katowice and Kraków fog was clearly related to anticyclonic types with air advection from the southeastern sector (Sa, SEa) and nonadvective types Ca and Ka, while in Latvia (Avotniece et al 2015) the most favourable conditions for fog formation exist during anticyclonic situations with air advection from S, SW and W. Anticyclonic conditions also favoured fog occurrence in Oxford in the winter season (Gomez and Smith 1984). Moreover, the long-term variability of fog frequency in Latvia in the 52-year-long period of 1960-2012 was similar to that in Kraków (Avotniece et al 2015).…”

Section: Discussionmentioning

confidence: 96%

Synoptic climatology of fog in selected locations of southern Poland (1966–2015)

Łupikasza

Niedźwiedź

2016

Bulletin of Geography. Physical Geography Series

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Abstract. This paper investigates fog frequency in southern Poland in relation to various topography (concave and convex forms) and atmospheric circulation types. It also discusses long-term variability in the annual and seasonal number of days with fog. Daily information on fog occurrence was taken from three high quality synoptic stations representing various landforms: Kraków-Balice (bottom of the hollow), Katowice-Muchowiec (Silesian Upland) and Bielsko-Aleksandrowice (summit of Carpathian Foothill). In the central part of southern Poland during the last 50 years fog occurred on average during 53-67 days a year. The annual number of foggy days in Kraków (67 days) located in a structural basin was by 14-15 days higher than in Bielsko (53 days) situated in the Silesian Foothills. In the annual course, high fog occurrence (above 6 days per month) was observed from September to January, with the maximum in Kraków (10 days in October). At every station the monthly minimum of fog occurrence fell in July (2 days). In summer and spring the highest probability of fog occurrence was found on days with anticyclonic types and air advection from the northeastern (Na, NEa) and eastern (Ea, SEa) sectors. In autumn, a high probability was also found for the anticyclonic types with advection of air mass from the eastern and southern sectors. In the Carpathian Foothills (Bielsko) the probability of fog occurrence in winter was significantly enhanced only for the cyclonic types with air advection from the eastern sector (NEc, Ec, SEc) and nonadvective types Cc (cyclone centre) and Bc (cyclonic trough). Trends in the fog frequency were mostly insignificant. The only significant decreasing trend was found in Kraków on the annual scale and in summer when fog frequency was low.

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Fog climatology in Latvia

Cited by 20 publications

References 23 publications

Patterns and trends of high-impact weather in China during 1959–2014

Patterns and trends of high-impact weather in China during 1959–2014

A Hybrid Approach for Fog Retrieval Based on a Combination of Satellite and Ground Truth Data

Synoptic climatology of fog in selected locations of southern Poland (1966–2015)

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