Identification of Air Masses Responsible for Warm Events on the East Antarctic Coast

Kurita, Naoyuki; Hirasawa, Naohiko; Koga, Shunsaku; Matsushita, Junji; Steen‐Larsen, Hans Christian; Masson‐Delmotte, Valérie; Fujiyoshi, Yasushi

doi:10.2151/sola.2016-060

Cited by 7 publications

(5 citation statements)

References 53 publications

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“…9a), which is important in determining the precipitation phase and potential for surface melt. This finding is in line with earlier work by Kurita et al (2016) showing that surface air temperature frequently exceeds 0°C during warm events at Syowa. This near-surface humidity inversion is completely missed by both reanalyses, underestimating the median value compared to the radiosonde composite by up to 0.7 g kg −1 (Fig.…”

Section: Enhanced Mt Events During 2009−19supporting

confidence: 93%

Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica

et al. 2020

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Atmospheric rivers (ARs) are an important component of the hydrological cycle linking moisture sources in lower latitudes to the Antarctic surface mass balance. We investigate AR signatures in the atmospheric vertical profiles at the Dronning Maud Land coast, East Antarctica, using regular and extra radiosonde measurements conducted during the Year of Polar Prediction Special Observing Period November 2018 to February 2019. Prominent AR events affecting the locations of Neumayer and Syowa cause a strong increase in specific humidity extending through the mid-troposphere and a strong low-level jet (LLJ). At Neumayer, the peak in the moisture inversion (up to 4 g kg −1) is observed between 800 and 900 hPa, while the LLJ (up to 32 m s −1) is concentrated below 900 hPa. At Syowa the increase in humidity is less pronounced and peaks near the surface, while there is a substantial increase in wind speed (up to 40 m s −1) between 825 and 925 hPa. Moisture transport (MT) within the vertical profile during the ARs attains a maximum of 100 g kg −1 m s −1 at both locations, and is captured by both ERA-Interim and ERA5 reanalysis data at Neumayer, but is strongly underestimated at Syowa. Composites of the enhanced MT events during 2009−19 show that these events represent an extreme state of the lower-tropospheric profile compared to its median values with respect to temperature, humidity, wind speed and, consequently, MT. High temporal-and vertical-resolution radiosonde observations are important for understanding the contribution of these rare events to the total MT towards Antarctica and improving their representation in models.

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Section: Enhanced Mt Events During 2009−19supporting

confidence: 93%

Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica

et al. 2020

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“…Therefore, it is a plausible hypothesis that shifts between such air masses largely explain the observed isotope dynamics close to the Mertz glacier. The more depleted isotopic composition and higher d‐excess of vapor over the ice sheet is generally thought to result from the distillation effect of cloud formation with contributions from both equilibrium and kinetic fractionation (Jouzel & Merlivat, 1984; Kurita et al., 2016a; Masson‐Delmotte et al., 2008). However, the sublimation and deposition fluxes including isotopic fractionation also influence the variability of the vapor isotopic signal.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies at other coastal polar sites have found distinct isotopic signatures for air masses advected from the ocean and those advected from the ice sheet (e.g., Bréant et al, 2019;Kopec et al, 2014;Kurita et al, 2016aKurita et al, , 2016b. Therefore, it is a plausible hypothesis that shifts between such air masses largely explain the observed isotope dynamics close to the Mertz glacier.…”

Section: Drivers Of the Vapor Isotopic Compositionmentioning

confidence: 90%

“…Synoptic weather events led to variations over multiple days, superimposed on the seasonal cycle. At Syowa station, coastal East Antarctica, Kurita et al (2016a) also found a strong influence of synoptic weather systems, causing advection of marine or glacial air masses with distinct isotopic signatures. At other coastal polar sites, shifts between these air masses manifest themselves in pronounced diurnal cycles in the vapor isotopic composition, at least in summertime high-pressure periods.…”

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confidence: 99%

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A Case Study on Drivers of the Isotopic Composition of Water Vapor at the Coast of East Antarctica

et al. 2023

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Stable water isotopes (SWIs) contain valuable information on the past climate and phase changes in the hydrologic cycle. Recently, vapor measurements in the polar regions have provided new insights into the effects of snow‐related and atmospheric processes on SWIs. The purpose of this study is to elucidate the drivers of the particularly depleted vapor isotopic composition measured on a ship close to the East Antarctic coast during the Antarctic Circumnavigation Expedition in 2017. Reanalysis data and backward trajectories are used to model the isotopic composition of air parcels arriving in the atmospheric boundary layer (ABL) above the ship. A simple model is developed to account for moisture exchanges with the snow surface. The model generally reproduces the observed trend with strongly depleted vapor δ18O values in the middle of the 6‐day study period. This depletion is caused by direct air mass advection from the ice sheet where the vapor is more depleted in heavy SWIs due to distillation during cloud formation. The time spent by the air masses in the marine ABL shortly before arrival at the ship is crucial as ocean evaporation typically leads to an abrupt change in the isotopic signature. Snow sublimation is another important driver when the isotopic composition of the sublimation flux differs substantially from that of the advected air mass, for example, marine air arriving at the coast or free‐tropospheric air descending from high altitudes. Despite strong simplifications, our model is a useful and computationally efficient method for understanding SWI dynamics at polar sites.

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“…The details are shown in Stein et al (2015). The HYSPLIT model has been used in many earlier studies to classify the source of aerosols over the SO (e.g., Kurita et al, 2016;Neff & Bertler, 2015;Uetake et al, 2020). Given the estimated residence time of bacteria in the atmosphere, 3-day was considered a period suitable for evaluating bacterial sources (Uetake et al, 2020).…”

Section: Hysplit Modelmentioning

confidence: 99%

Ice Cloud Formation Related to Oceanic Supply of Ice‐Nucleating Particles: A Case Study in the Southern Ocean Near an Atmospheric River in Late Summer

Sato,

Inoue

2023

Geophysical Research Letters

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This study investigated ice cloud formation associated with marine bioaerosols over the Southern Ocean (SO) using a combination of cloud particle sensor (CPS) sonde observations, satellite products, reanalysis data, and backward trajectory analysis. The CPS sonde detected ice clouds at temperatures higher than −10°C in the mid‐troposphere near an atmospheric river at high‐latitudes over the SO. Backward trajectory analyses indicated that a mid‐latitude air mass with a high concentration of atmospheric dimethylsulfide (DMS) in the atmospheric boundary layer (<1 km) arrived at the ice cloud formation layer over the high‐latitudes. The DMS in the boundary layer began to increase under high wave conditions, coincident with the highest chlorophyll‐a concentrations in the ocean. These results suggest that bioaerosols emitted from the ocean over the mid‐latitudes acted as ice‐nucleating particles for ice cloud formation over high‐latitudes.

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Identification of Air Masses Responsible for Warm Events on the East Antarctic Coast

Cited by 7 publications

References 53 publications

Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica

Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica

A Case Study on Drivers of the Isotopic Composition of Water Vapor at the Coast of East Antarctica

Ice Cloud Formation Related to Oceanic Supply of Ice‐Nucleating Particles: A Case Study in the Southern Ocean Near an Atmospheric River in Late Summer

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