Seasonal distribution and variability of atmospheric freeze/thaw cycles in <scp>N</scp>orway over the last six decades (1950–2013)

Kerguillec, Riwan

doi:10.1111/bor.12113

Cited by 10 publications

(10 citation statements)

References 14 publications

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“…Here, we use zero crossings based on air temperature as a proxy for slippery conditions. A zero crossing is defined as T min < 0 and T max > 0 on the same day (Geiger et al, 2007;Kerguillec, 2015). Although zero crossings calculated from 2 m air temperature do not coincide perfectly with slippery conditions, they have the advantage of being available for the future period at 1 km resolution, as opposed to road temperature and dew point temperature and humidity.…”

Section: Climate Indicesmentioning

confidence: 99%

“…Trends are, however, sensitive to the choice of period. This is shown by Kerguillec (2015), who studied zero crossings in Norway using daily thermal data from 20 meteorological stations for the period 1950-2013, including two stations in Troms. For these two stations, the frequency of zero crossings increased during the periods 1970-1979and 1990-1999but decreased in the 1980s.…”

Section: Zero Crossingsmentioning

confidence: 99%

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Present and future changes in winter climate indices relevant for access disruptions in Troms, northern Norway

Dyrrdal

Isaksen

Jacobsen

et al. 2020

Nat. Hazards Earth Syst. Sci.

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Abstract. A number of seaside communities in Troms, northern Norway, are vulnerable to sudden weather-induced access disruptions due to high-impact weather and dependency on one or few roads. In this paper we study changes in winter weather known to potentially cause access disruptions in Troms, for the present climate (1958–2017) and two future periods (2041–2070; 2071–2100). We focus on climate indices associated with snow avalanches and weather that may lead to for example slippery road conditions. In two focus areas, the most important results show larger snow amounts now compared to 50 years ago, and heavy snowfall has become more intense and frequent. This trend is expected to turn in the future, particularly at low elevations where snow cover during winter might become a rarity by 2100. Strong snow drift, due to a combination of snowfall and wind speed, has slightly increased in the two focus areas, but a strong decrease is expected in the future due to less snow. Events of heavy rain during winter are rather infrequent in the present winter climate of Troms, but we show that these events are likely to occur much more often in all regions in the future.

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Section: Climate Indicesmentioning

confidence: 99%

Section: Zero Crossingsmentioning

confidence: 99%

Present and future changes in winter climate indices relevant for access disruptions in Troms, northern Norway

Dyrrdal

Isaksen

Jacobsen

et al. 2020

Nat. Hazards Earth Syst. Sci.

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“…Trends are, however, very sensitive to the choice of period.. This is clearly shown by Kerguillec (2015), who studied atmospheric freeze/thaw cycles (zero-crossings) in Norway using daily thermal data from 20 meteorological stations for the period 1950-2013. Different decades displayed different trend directions and magnitudes at the different stations.…”

Section: Future Developmentmentioning

confidence: 99%

Present and future changes in winter climate indices relevant for access disruptions in Troms, northern Norway

Dyrrdal¹,

Isaksen²,

Jacobsen³

et al. 2019

Preprint

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Abstract. In some seaside communities in northern Norway the vulnerability to weather induced access disruptions is high, due to frequent high impact weather in the region and the dependency on one or few roads particularly exposed to avalanches, wind and rockfall. In this paper we study changes in typical winter weather indices known to potentially cause such access disruptions in the region. A gridded observation-based dataset is used to analyse changes in present climate (1958–2017), while an ensemble of 10 EURO-CORDEX climate model simulations are used to assess expected future changes in the same indices, towards the end of this century. We focus on weather indices associated with snow avalanches, such as maximum snow amount and snowfall intensity and frequency, but also freeze-thaw cycles in terms of temperatures crossing zero degrees Celsius (zero-crossings), total water supply and the frequency of high wind speed are studied. Our results show that there are large climate gradients in Troms county and also in detected changes. In both focus areas, however, we find an increase in studied snow indices in present climate, while a strong decrease is expected in near and far future, particularly in low elevations where snow during winter might become a rarity by 2100. Heavy water supply is rather infrequent in the present climate of Troms, but we show that these events are likely to occur more often in all inland areas in the future. Although the risk of dry snow-related access disruptions might decrease, a warmer and wetter winter climate may increase the risk of wet-snow avalaches and slushflows. We find that zero-crossings, known to destabilize the snow pack and cause rockfall, have increased in most parts of Troms during the last decades, and a further increase is expected for inland regions in the future, while coastal regions can expect less zero-crossings. The higher risk of water and rainfall-induced hazards and more frequent freeze-thaw conditions calls for careful coordination of climate adaptation, cooperation between different sectors, as well as guidance and training of local authorities, especially in exposed and remote regions.

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“…The topic of this study is, however, zero-crossings of the two-metre air temperature. Kerguillec (2015) studied historical trends and variability in annual and seasonal numbers of DZCs for 20 weather stations in Norway during the period 1950-2013. He concluded that, because DZCs are most frequent in months with the mean temperature close to 0 C, both the average number of such crossings and the trends during different decades differ with altitude, latitude and distance from the coast.…”

Section: Introductionmentioning

confidence: 99%

“…They used the number of days with mean temperature from −1.5 to +1.0 C as a proxy for the number of DZCs. Neither Kerguillec (2015) nor Dyrrdal et al (2011) included climate projections. Miles et al (2011) estimated changes in the frequencies of DZCs in different seasons up to 2050, based on a 4-member ensemble of climate models under the A1B emission scenario.…”

Section: Introductionmentioning

confidence: 99%

Projected changes in days with zero‐crossings for Norway

Nilsen

Hanssen-Bauer

Tveito

et al. 2020

Intl Journal of Climatology

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This paper describes annual and seasonal changes in the number of days with 0 C crossings, comparing projections (2071-2100) based upon regional climate model (RCM) results under the medium and high emission scenarios with the period 1971-2000. A trend analysis of historical observations of days with zero-crossings (DZCs) for the period 1971-2016 showed a general increase in DZCs in cold seasons and regions and a decrease in DZCs in mild seasons and regions. A cold bias in the unadjusted EURO-CORDEX model ensemble rendered bias-adjustment necessary before analyses. In regions and seasons that are mild, temperatures will exceed 0 C during a larger part of the year by the end of this century, and the number of DZCs is thus projected to decrease. This decrease was found for lowland regions in spring and coastal regions in winter. In regions and seasons that are cold, temperatures will rise up above 0 C for a larger part of the year, such that the number of DZCs is projected to give more frequent crossings of the 0 C threshold. This increase was found for inland regions in winter and Finnmark, the northernmost county, in spring. Thus, more frequent icing of the snowpack is expected in Finnmark. However, less frequent icing in coastal and lowland regions may indicate a lesser need for winter road maintenance.

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Seasonal distribution and variability of atmospheric freeze/thaw cycles in Norway over the last six decades (1950–2013)

Cited by 10 publications

References 14 publications

Present and future changes in winter climate indices relevant for access disruptions in Troms, northern Norway

Present and future changes in winter climate indices relevant for access disruptions in Troms, northern Norway

Present and future changes in winter climate indices relevant for access disruptions in Troms, northern Norway

Projected changes in days with zero‐crossings for Norway

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