Seasonal Variations in High Arctic Free Tropospheric Aerosols Over Ny‐Ålesund, Svalbard, Observed by Ground‐Based Lidar

Shibata, Takashi; Shiraishi, Koichi; Shiobara, Masataka; Iwasaki, S.; Takano, Toshiaki

doi:10.1029/2018jd028973

Cited by 13 publications

(11 citation statements)

References 49 publications

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“…With a Nd:YAG laser-based Mie depolarization Lidar system, also located in Ny-Ålesund, a similar pattern of the mean annual cycle of the aerosol load with decreasing importance of the Arctic haze season was recently found [40].…”

Section: Trends In the Aodsupporting

confidence: 53%

“…However, the wide range of the modified Ångström exponent α and its spectral slope β in August indicates that during summer, the free troposphere might see a different aerosol load than the surface. Indeed, in the Lidar observations of Shibata et al [40], an increased backscatter signal was found during summer months up to about an altitude of 5 km.…”

Section: Histograms Of Aerosol Load and Propertiesmentioning

confidence: 91%

“…Hence, the role as the ocean being only a sink for aerosol might not be so clear during summer. Second, due to the results of the previous section, the aerosol might be more diverse and arrive at higher altitudes during summer [40].…”

Section: Remarks On the Advection Altitudementioning

confidence: 95%

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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: Trends In the Aodsupporting

confidence: 53%

Section: Histograms Of Aerosol Load and Propertiesmentioning

confidence: 91%

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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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“…Because no observations of M BC distribution near Ny‐Ålesund have been made in other seasons, it is difficult to interpret the seasonal variations in the correlation between C MBC and M BC . Ground‐based measurements near Ny‐Ålesund during 2014–2017 showed that the backscattering coefficient of aerosols was vertically uniform in the PBL and lower troposphere in all seasons (Shibata et al., 2018). However, this feature may not apply to BC, and the effect of variability of vertical profiles of BC is inconclusive.…”

Section: Bc Wet Removalmentioning

confidence: 99%

Seasonal Variation of Wet Deposition of Black Carbon at Ny‐Ålesund, Svalbard

et al. 2021

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Black carbon (BC) aerosol deposited in and onto Arctic snow increases the snow's absorption of solar radiation and accelerates snowmelt. Concentrations of BC in the Arctic atmosphere and snow are controlled by wet deposition; however, details of this process are poorly understood owing to the scarcity of time-resolved measurements of BC in hydrometeors. We measured mass concentrations of BC in hydrometeors (CMBC) and in air (MBC) with 16% and 15% accuracies, respectively, at Ny-Ålesund, Svalbard during 2012-2019. Median monthly MBC and CMBC values showed similar seasonal variations, being high in winter-spring and low in summer. Median monthly BC wet deposition mass flux (FMBC) was highest in winter and lowest in summer, associated with seasonal patterns of CMBC and precipitation. Seasonally averaged BC size distributions in hydrometeors were similar except for summer.Measurements of MBC and CMBC in spring 2017 showed a size-independent removal efficiency, indicating that BC-containing particles were efficiently activated into cloud droplets. These observations at Ny-Ålesund were compared with observations at Barrow, Alaska, during 2013-2017. The near-surface MBC at Ny-Ålesund and Barrow had similar seasonal patterns; however, the two sites differed in CMBC and FMBC. In summer, CMBC was low at Ny-Ålesund but moderate at Barrow, likely reflecting differences in MBC in the lower troposphere. Seasonally averaged BC size distributions in hydrometeors were similar at both sites, suggesting that average BC size distributions are similar in the Arctic lower troposphere. The efficiency of BC removal tends to be size-independent during transport, leading to the observed similarity.

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“…This seasonality is reflected upon the aerosol optical properties, with a late winter-spring scattering coefficient maximization (median values even higher than 10 Mm −1 ) [10]. While in winter, maximal extinction occurs in the lower Arctic troposphere, in spring, there is a progressive shift towards the middle and upper troposphere [13][14][15]. The extinction enhancement in higher altitudes ("Arctic haze") is associated with the isentropic poleward transport of polluted mid-latitude air masses [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Does the Intra-Arctic Modification of Long-Range Transported Aerosol Affect the Local Radiative Budget? (A Case Study)

et al. 2020

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The impact of aerosol spatio-temporal variability on the Arctic radiative budget is not fully constrained. This case study focuses on the intra-Arctic modification of long-range transported aerosol and its direct aerosol radiative effect (ARE). Different types of air-borne and ground-based remote sensing observations (from Lidar and sun-photometer) revealed a high tropospheric aerosol transport episode over two parts of the European Arctic in April 2018. By incorporating the derived aerosol optical and microphysical properties into a radiative transfer model, we assessed the ARE over the two locations. Our study displayed that even in neighboring Arctic upper tropospheric levels, aged aerosol was transformed due to the interplay of removal processes (nucleation scavenging and dry deposition) and alteration of the aerosol source regions (northeast Asia and north Europe). Along the intra-Arctic transport, the coarse aerosol mode was depleted and the visible wavelength Lidar ratio (LR) increased significantly (from 15 to 64–82 sr). However, the aerosol modifications were not reflected on the ARE. More specifically, the short-wave (SW) atmospheric column ARE amounted to +4.4 - +4.9 W m−2 over the ice-covered Fram Strait and +4.5 W m−2 over the snow-covered Ny-Ålesund. Over both locations, top-of-atmosphere (TOA) warming was accompanied by surface cooling. These similarities can be attributed to the predominant accumulation mode, which drives the SW radiative budget, as well as to the similar layer altitude, solar geometry, and surface albedo conditions over both locations. However, in the context of retreating sea ice, the ARE may change even along individual transport episodes due to the ice albedo feedback.

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Seasonal Variations in High Arctic Free Tropospheric Aerosols Over Ny‐Ålesund, Svalbard, Observed by Ground‐Based Lidar

Cited by 13 publications

References 49 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

Seasonal Variation of Wet Deposition of Black Carbon at Ny‐Ålesund, Svalbard

Does the Intra-Arctic Modification of Long-Range Transported Aerosol Affect the Local Radiative Budget? (A Case Study)

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