Twenty-five years of cloud base height measurements by ceilometer in Ny-Ålesund, Svalbard

Maturilli, Marion; Ebell, Kerstin

doi:10.5194/essd-10-1451-2018

Cited by 28 publications

(35 citation statements)

References 15 publications

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“…Cases of wet air below 1000 m altitude drastically reduced the number of available photometer measurements. This is in agreement with Maturilli and Ebell [1], who derived from ceilometer observations that the cloud bottom at Ny-Ålesund was generally below a 1000 m altitude. From this follows that aerosol above a 1000 m altitude may survive cloud formation and is not being washed out.…”

Section: Aerosol Sources and Sinkssupporting

confidence: 92%

“…Green circles are individual measurements, the colored lines the fitted exponential law. Left: The data were fitted with the traditional Ångström law of Equation (1). Right: Equation (2) with two wavelength ranges of the UV and visible (<700 nm) and the near-infrared (>700 nm) were used for the same dataset.…”

Section: Figurementioning

confidence: 99%

“…However, these possibilities are not available over sea ice, which why this fraction is the smallest (Figure 13, bottom right). Because, typically, clouds lie below the arriving height of the back-trajectories at 1500 m [1], the aerosol is not washed out after it arrives in the free troposphere.…”

Section: Remarks On the Advection Altitudementioning

confidence: 99%

“…The Arctic is climatologically a key region, which shows the largest temperature increase in the world, especially in the European Arctic around Svalbard, with a dramatic increase of about 3 K per decade during winter [1]. Due to the retreating sea ice, the Arctic warms quicker than other regions on Earth.…”

Section: Introductionmentioning

confidence: 99%

“…Every trajectory was backward computed starting at 11 UTC at heights of 500, 1000, and 1500 m above sea level (asl) over Zeppelin Station, Ny-Ålesund, Svalbard. Ceilometer measurements showed that precipitating clouds reached a typical height of 1000 m over Ny-Ålesund [1]. Hence, the trajectories were computed below, within and above potential clouds to see the influence of hygroscopic growth on the particles and on the measured AOD by the photometer.…”

Section: Introductionmentioning

confidence: 99%

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Properties of Arctic Aerosol Based on Sun Photometer Long-Term Measurements in Ny-Ålesund, Svalbard

Graßl

Ritter

2019

Remote Sensing

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On the basis of sun photometer measurements located at the German-French polar research base AWIPEV in 11.928 • E), Svalbard, long-term changes (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017) of aerosol properties in the European Arctic are analyzed with the main focus on physical aerosol properties like Aerosol Optical Depth (AOD) and the Ångström exponent during the Arctic haze season in spring compared with summer and autumn months. In order to gain more information from the photometer data and to reduce the error of fitting the data to the Ångström law, a new approach with an Ångström exponent, which depends linearly on wavelength, is presented in this paper. With the Mie program of libRadtran, a calculator for long-and short-wave radiation through the Earth's atmosphere, artificial aerosol size distributions were created to extend the physical understanding of this modified Ångström law. Monthly means of the measured AOD of the years 1994-2017 are presented to analyze long-term changes of aerosol properties and its load. Because photometer data in general have no height information, a comparison with a Lidar located at the same site is presented. The so-obtained data are then compared with the previous Mie calculus. More homogeneous aerosol properties were found during spring and more heterogeneous in summer. To study possible aerosol sources and sinks, five-day back-trajectories were calculated with the FLEXPART model at three different arriving heights at 11 UTC in the village Ny-Ålesund. Besides the pollution pathway of the aerosol into the European Arctic based on the calculated back-trajectories, the influence of the boundary layer parameterized by the lowermost 100 hPa atmospheric layer is analyzed and compared to the measured aerosol load by the photometer in Ny-Ålesund additionally. During spring, the open ocean acts as a sink for aerosols, whereas sea ice clearly reduces their sinks. Hence, trajectories over sea ice are correlated to higher aerosol loads. Thus, both sources and sinks must be considered to understand aerosol occurrences in the Arctic.

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Section: Aerosol Sources and Sinkssupporting

confidence: 92%

Section: Figurementioning

confidence: 99%

Section: Remarks On the Advection Altitudementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Properties of Arctic Aerosol Based on Sun Photometer Long-Term Measurements in Ny-Ålesund, Svalbard

Graßl

Ritter

2019

Remote Sensing

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Transfer Learning Aurora Image Classification and Magnetic Disturbance Evaluation

Sado

Clausen

Miloch

et al. 2021

Preprint

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Created by particles precipitating into the ionosphere, the aurora are a direct consequence of interactions between the solar wind and the magnetosphere. A connection between different auroral shapes and behaviors simultaneously across the polar region has been first shown in 1964, when analyzing auroral images taken across northern continental America and Antarctica (Akasofu, 1964). The established model of auroral substorms, describes the activity of the aurora from its beginning, when the aurora is calm, over active phases toward another calm phase. This model was later refined to include the three currently used phases "growth", "expansion" and "recovery" (McPherron et al., 1973). Interaction between the solar wind and the interplanetary magnetic field lead to storage of energy in the magnetosphere during the growth phase. In the expansion phase energy is released, before the magnetosphere returns to normal conditions in the recovery phase.Since the beginning of auroral research, images have therefore been an important tool to analyze and diagnose the complex processes in the ionosphere and magnetosphere, often supplemented by magnetometers measuring the local Earth's magnetic field or satellites performing similar measurements. All Sky Imagers, taking pictures of the night sky and capturing aurora in regular intervals, can for example, be found in Ny-Ålesund and Longyearbyen

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Observed and modelled cloud cover up to 6 km height at Station Nord in the high Arctic

Gryning

Batchvarova

Floors

et al. 2020

Intl Journal of Climatology

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We present results from an analyses of cloud cover based on profiles of the attenuated backscatter coefficient from an 8-year-long data series (July 2011-April 2019). The observations are carried out in the high Arctic by a ceilometer with a maximum range setting of 7.7 km from the Villum Research Station at Station Nord, Greenland. Results show that the hourly cloud cover turned out to follow a U-shaped rather than Gaussian-like distribution. Annual and seasonal cloud cover variation is illustrated. The cloud cover is larger during the autumn and winter as compared to summer and spring. The cloud cover exhibits a substantial variation from year to year without a clear trend. The cloud cover during spring is low and decreasing between 2012 and 2017. The cloud cover during the autumn of 2016 is lowest compared to the other years. The observed cloud cover is compared to the cloud cover provided in the ERA5 reanalysis dataset. The cloud cover for low clouds and medium clouds are combined to represent a total height of 6 km. Both the observed and modelled cloud cover is larger during winter as compared to summertime cloud cover. The measured reduction in the cloud cover for the autumn of 2016 is present in the reanalysis data as well but the measured low cloud cover during spring is not apparent in the reanalysis data. Because the cloud cover distribution is U-shaped rather than of a Gaussian nature, standard metrics are not applicable. We apply a generalized skill score that is developed for contingency tables or joint histograms. Three skill scores were calculated. It was found that for all three methods, skills for the predictability of the cloud cover by the ERA5 modelling is better for winter than summer and is poor during the spring.

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Twenty-five years of cloud base height measurements by ceilometer in Ny-Ålesund, Svalbard

Cited by 28 publications

References 15 publications

Properties of Arctic Aerosol Based on Sun Photometer Long-Term Measurements in Ny-Ålesund, Svalbard

Properties of Arctic Aerosol Based on Sun Photometer Long-Term Measurements in Ny-Ålesund, Svalbard

Transfer Learning Aurora Image Classification and Magnetic Disturbance Evaluation

Observed and modelled cloud cover up to 6 km height at Station Nord in the high Arctic

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