The influence of air temperature and atmospheric circulation on winter fog frequency over Northern Eurasia

Ye, Hengchun

doi:10.1002/joc.1741

Cited by 21 publications

(20 citation statements)

References 14 publications

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“…In summer the effect of circulation is more dependent on also noted by Ye (2009) and ascribed to the decreased availability of water vapour in high-pressure situations.…”

Section: Effects Of Geostrophic Flows On Low Visibilitymentioning

confidence: 84%

“…We can now find an estimate of the trend in the number of low visibility days due to circulation changes by multiplying the trends in geostrophic wind and vorticity with the regression on these indices: also noted by Ye (2009) and ascribed to the decreased availability of water vapour in high-pressure situations.…”

Section: Trends In Circulation and Their Effect On Low Visibilitymentioning

confidence: 97%

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On the roles of circulation and aerosols in the decline of mist and dense fog in Europe over the last 30 years

2010

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Abstract. Fog and mist are meteorological phenomena that have significant contributions to temperature variations. Understanding and predicting them is also crucial for transportation risk management. It has been shown that low visibility phenomena over Europe have been declining over the past three decades. The trends in mist and haze have been correlated to atmospheric aerosol trends. However, dense fog has not received yet such focus. The goal of this paper is to examine the roles of synoptic atmospheric circulation and aerosol content on the trends of dense fog. We show that sulphur emission trends are spatially correlated with visibility trends, with a maximum correlation when visibility is between 1 km and 10 km. We find that atmospheric dynamics overall contributes up to 40% of the variability of the frequency of fog occurrences. This contribution is spatially variable and highly depends on the topography and the season, with higher values in the winter. The observed long-term circulation changes do not contribute much to the trends in low visibility found in the data. This process is illustrated on three stations (De Bilt, Zürich Airport and Potsdam) for which a long-term visibility data and a thorough meteorological description are available. We conclude that to properly represent fog in future climate simulations, it is necessary to include realistic representations of aerosol emissions and chemistry, land surface properties and atmospheric dynamics.

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“…In summer the effect of circulation is more dependent on also noted by Ye (2009) and ascribed to the decreased availability of water vapour in high-pressure situations.…”

Section: Effects Of Geostrophic Flows On Low Visibilitymentioning

confidence: 84%

Section: Trends In Circulation and Their Effect On Low Visibilitymentioning

confidence: 97%

On the roles of circulation and aerosols in the decline of mist and dense fog in Europe over the last 30 years

2010

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“…Dense fog disappeared completely in 1997 at both stations, but rebounded somewhat in more recent years. Table 1 Average annual hours visibility \400 m (excludes 1998 for BUR) LAX 1948-200973 LGB 1948-2009107 LAX 1966-200944 LGB 1966-200959 BUR 1982-20067 CBD 1961-196410 CBD 2000-2006 Hours visibility <400 m at LAX , 1948, -2008, Vol. 169, (2012 The Continued Reduction in Dense Fog 1159…”

Section: Resultsmentioning

confidence: 99%

The Continued Reduction in Dense Fog in the Southern California Region: Possible Causes

LaDochy

Witiw

2011

Pure Appl. Geophys.

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Dense fog appears to be decreasing in many parts of the world, especially in western cities. Dense fog (visibility \400 m) is disappearing in the urban southern California area also. There the decrease in dense fog events can be explained mainly by declining particulate levels, Pacific sea surface temperatures (SST), and increased urban warming. Using hourly data from 1948 to the present, we looked at the relationship between fog events in the region and contributing factors and trends over time. Initially a strong relationship was suggested between the occurrence of dense fog and the phases of an atmosphere-ocean cycle: the Pacific Decadal Oscillation (PDO). However, closer analysis revealed the importance to fog variability of an increasing urban heat island and the amount of atmospheric suspended particulate matter. Results show a substantial decrease in the occurrence of very low visibilities (\400 m) at the two airport stations in close proximity to the Pacific Ocean, LAX (Los Angeles International) and LGB (Long Beach International). A downward trend in particulate concentrations, coupled with an upward trend in urban temperatures were associated with the decrease in dense fog occurrence at both LAX and LGB. LAX dense fog that reached over 300 h in 1950 dropped steadily, with 0 h recorded in 1997. Since 1997, there has been a slight recovery with both 2008 and 2009 recording over 30 h of dense fog at both locations. In this study we examine whether the upturn is a temporary reversal of the trend. To remove the urban effect, we also included fog data from Vandenberg Air Force Base (VBG), located in a relatively sparsely populated area approximately 200 km to the north of metropolitan Los Angeles. Particulates, urban heat island, and Pacific SSTs all seem to be contributing factors to the decrease in fog in southern California, along with large-scale atmosphereocean interaction cycles. Case studies of local and regional dense fog in southern California point to the importance of strong, low inversions and to a lesser contributor, Santa Ana winds. Both are associated with large-scale atmospheric circulation patterns, which have changed markedly over the period of studied. These changes point to continued decreases in dense fog in the region.

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“…First, it is the largest landmass over high latitudes, where climate change has been amplified and seasonality is significant. Second, relatively long and continuous historical data exists over the region, and extensive research has been done on changes in the hydrological cycles including atmospheric water vapor/humidity [Serreze et al, 2003;Ye and Fetzer, 2010;Zhang et al, 2012], precipitation [Groisman and Rankova, 2001;Ye, 2001Ye, , 2008, river discharges [Rawlins et al, 2009;Yang et al, 2002;Ye et al, 2004], and permafrost conditions [Zhang et al, 2005]. Finally, conclusions derived from this region have implications for other high-latitude regions and are potentially significant to our understanding of climate change at a global scale.…”

Section: Publicationsmentioning

confidence: 99%

Impact of increased water vapor on precipitation efficiency over northern Eurasia

Fetzer

Wong

et al. 2014

Geophysical Research Letters

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This study investigates the relationships among water vapor, precipitation efficiency, precipitation amount, and air temperature anomalies on monthly time scales over northern Eurasia for winter and summer 2003–2010. Daily precipitation and temperature records at 505 historical stations, and atmospheric total precipitable water vapor and relative humidity data from Atmospheric Infrared Sounders, are used for analysis. Results show that higher atmospheric precipitable water associated with warmer temperature directly contributes to winter precipitation amount but has little impact on winter precipitation efficiency. However, accelerated decreasing relative humidity associated with higher temperature is the primary factor in the reduction of precipitation efficiency and precipitation amount regardless of higher precipitable water in summer. This study suggests that there are evident seasonal differences in precipitation trend associated with air temperature changes over the study region. Air temperature modifies a key atmospheric water variable that directly controls precipitation for that particular season.

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The influence of air temperature and atmospheric circulation on winter fog frequency over Northern Eurasia

Cited by 21 publications

References 14 publications

On the roles of circulation and aerosols in the decline of mist and dense fog in Europe over the last 30 years

On the roles of circulation and aerosols in the decline of mist and dense fog in Europe over the last 30 years

The Continued Reduction in Dense Fog in the Southern California Region: Possible Causes

Impact of increased water vapor on precipitation efficiency over northern Eurasia

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