The Sensible Heat Flux in the Course of the Year at Ny-Ålesund, Svalbard: Characteristics of Eddy Covariance Data and Corresponding Model Results

Jocher, Georg; Schulz, Alexander; Ritter, Christoph; Neuber, Roland; Dethloff, Klaus; Foken, Thomas

doi:10.1155/2015/852108

Cited by 5 publications

(5 citation statements)

References 29 publications

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“…The dashed circles represent the relative frequency of the wind direction at a 5%, 10% and 15% level. As already Jocher et al [25] observed in the data of the nearby eddy covariance station, three major wind directions in the ABL of Kongsfjord are found: the most dominant one in every season and over all these years is ESE (east south east), parallel to the orientation of the fjord and the interior of Svalbard with huge ice fields. The second one is pointing to the entrance of Kongsfjord in the north-westerly (NW) direction.…”

Section: Wind Patterns In Selected Altitudessupporting

confidence: 72%

“…The last one is pointing towards the south-west (SW) with a peak at about 220-230 • . Jocher et al [25] connected this flow with katabatic outflows of the glacier Brøggerbreen and the comparable low mountains of the ridge on Brøggerhalvøya. The four months February, May, August and November were chosen in Figure 5 as representatives of each season because they are special in their own way.…”

Section: Wind Patterns In Selected Altitudesmentioning

confidence: 99%

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The Nature of the Ny-Ålesund Wind Field Analysed by High-Resolution Windlidar Data

2022

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In this work we present windlidar data for the research village Ny-Ålesund located on Svalbard in the European Arctic (78.923°N, 11.928°E) from 2013 to 2021. The data have a resolution of 50 m and 10 min with an overlapping height of about 150 m. The maximum range depends on the meteorologic situation. Up to 1000 m altitude the data availability is better than 71%. We found that the highest wind speeds occur in November and December, the lowest ones in June and July, up to 500 m altitude the wind is channelled strongly in ESE to NW direction parallel to the fjord axis and the synoptic conditions above 1000 m altitude already dominate. While the fraction of windy days (v>10ms) varies significantly from month to month, there is no overall trend of the wind visible in our data set. We define gusts and jets by the requirement of wind maxima v>2ms above and below a wind maximum. In total, more than 24,000 of these events were identified (corresponding to 6% of the time), of which 223 lasted for at least 100 min (“Long Jets”). All of these events are fairly equally distributed over the months relatively to the available data. Further, gusts and jets follow different distributions (in terms of altitude or depths) and occur more frequently for synoptic flow from roughly a southerly direction. Jets do not show a clear correlation between occurrence and synoptic flow. Gusts and jets are not related to cloud cover. We conclude that the atmosphere from 400 m to 1000 m above Ny-Ålesund is dominated by a turbulent wind shear zone, which connects the micrometeorology in the atmospheric boundary layer (ABL) with the synoptic flow.

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Section: Wind Patterns In Selected Altitudessupporting

confidence: 72%

Section: Wind Patterns In Selected Altitudesmentioning

confidence: 99%

The Nature of the Ny-Ålesund Wind Field Analysed by High-Resolution Windlidar Data

2022

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“…Ny-Ålesund is embedded in the complex orography of fjord, glaciers, and mountain ranges of up to 800 m altitude. Micrometeorology plays an important role, especially in the lower troposphere [36,37]. The surrounding mountains create a wind channeling effect along the Kongsfjord with SE flow throughout the year and less frequently flow of the opposite NW direction.…”

Section: Measurement Sitementioning

confidence: 99%

Properties of Cirrus Clouds over the European Arctic (Ny-Ålesund, Svalbard)

2021

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Cirrus is the only cloud type capable of inducing daytime cooling or heating at the top of the atmosphere (TOA) and the sign of its radiative effect highly depends on its optical depth. However, the investigation of its geometrical and optical properties over the Arctic is limited. In this work the long-term properties of cirrus clouds are explored for the first time over an Arctic site (Ny-Ålesund, Svalbard) using lidar and radiosonde measurements from 2011 to 2020. The optical properties were quality assured, taking into account the effects of specular reflections and multiple-scattering. Cirrus clouds were generally associated with colder and calmer wind conditions compared to the 2011–2020 climatology. However, the dependence of cirrus properties on temperature and wind speed was not strong. Even though the seasonal cycle was not pronounced, the winter-time cirrus appeared under lower temperatures and stronger wind conditions. Moreover, in winter, geometrically- and optically-thicker cirrus were found and their ice particles tended to be more spherical. The majority of cirrus was associated with westerly flow and westerly cirrus tended to be geometrically-thicker. Overall, optically-thinner layers tended to comprise smaller and less spherical ice crystals, most likely due to reduced water vapor deposition on the particle surface. Compared to lower latitudes, the cirrus layers over Ny-Ålesund were more absorbing in the visible spectral region and they consisted of more spherical ice particles.

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“…Different authors used 30 min averages in analyses of this kind (e.g. Jocher et al , ). Kilpelinen and Sjblom () demonstrated by means of Ogive plots that a 30 min averaging period is appropriate for momentum flux, while for sensible heat flux an even a shorter period could be sufficient.…”

Section: Measurement Site and Datasetmentioning

confidence: 99%

“…Maturilli et al () presented a consistent meteorological dataset collected at Ny‐Ålesund from 1993 to 2011 but, even though these data provide a good picture of the climatological variation of the atmospheric variables in the area, they are not sufficient to describe the vertical structure of the ABL. Jocher et al () compared one year of sensible heat flux eddy covariance measurements performed at Ny‐Ålesund with corresponding model results. In order to extend the availability of this kind of measurement, a 34 m high tower was set up at Ny‐Ålesund, Svalbard in 2009 by the National Research Council of Italy (CNR).…”

Section: Introductionmentioning

confidence: 99%

Stable boundary layer vertical scales in the Arctic: observations and analyses at Ny‐Ålesund, Svalbard

Mazzola

Tampieri

Viola

et al. 2016

Quart J Royal Meteoro Soc

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taken at the Amundsen-Nobile Climate Change Tower located at Ny-Ålesund, Svalbard, allowed investigation of some features of the vertical structure of the atmospheric stable boundary layer (SBL) at high latitudes. The main sensors are three sonic anemometers and four low-frequency thermo-hygrometers and anemometers. The momentum flux τ , the sensible heat flux Q and the turbulent kinetic energy K data at different levels demonstrated the occurrence of both the traditional and upside-down SBL cases, according to the classification proposed in the literature. Based on a linear approximation of the profiles, the vertical scales were found to be different for the different second-order moments. In the traditional case, the scales h τ , h Q and h K , defined as levels for which fluxes became zero, can be considered to approximate the boundary-layer depth. While the distributions of h τ and h Q were found to be similar, having the ratio h Q /h τ equally distributed around unity although with a positive skewness, those of h τ and h K look quite different, having the ratio h K /h τ >1 in about 90% of the cases and with a median value >2. In the upside-down case, the scales s τ , s Q and s K , defined as the height at which the value of the considered quantity doubles that at the surface, give a measure of the vertical variations of the moments. Comparing the distributions of these three scales, similar results to those for the traditional case were found, although with slightly different statistics. The values of the ratio between scales affect the vertical profile of the local Obukhov length in both the traditional and upside-down SBL cases.

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The Sensible Heat Flux in the Course of the Year at Ny-Ålesund, Svalbard: Characteristics of Eddy Covariance Data and Corresponding Model Results

Cited by 5 publications

References 29 publications

The Nature of the Ny-Ålesund Wind Field Analysed by High-Resolution Windlidar Data

The Nature of the Ny-Ålesund Wind Field Analysed by High-Resolution Windlidar Data

Properties of Cirrus Clouds over the European Arctic (Ny-Ålesund, Svalbard)

Stable boundary layer vertical scales in the Arctic: observations and analyses at Ny‐Ålesund, Svalbard

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