An examination of the humidity correction by Vaisala RS80-A radiosondes for experiments and measurements at an inland Antarctic station

The present paper examines the correction of humidity measurements by the Vaisala RS80-A radiosonde using data obtained at Dome Fuji Station, inland Antarctica. The correction method is based upon a procedure developed by L.M. Miloshevich et al.(J. Atmos. Oceanic Technol., 18, 135, 2001). In the present study, experiments in a snow cave below ground, where a state of ice saturation is assumed, show that Miloshevich\u27s coefficient is appropriate for temperatures warmer than -45 °C because the corrected humidity reflects the state of ice saturation. Below these temperatures a correction coefficient is needed. At -55 °C , for example, a factor of 1.2 is needed. An examination using surface humidity data obtained from a routine aerological observation concluded that the correction coefficient is larger than Miloshevich\u27s at temperatures colder than -50 °C , so that the multiplication factor(0.185968×exp((-0.0339)×T); T=temperature) is needed to apply Miloshevich\u27s coefficient. After the correction is performed, the relative humidity with respect to ice becomes 150 on average in the lower temperature range. Perpetual falling of ice crystals indicates at least an occurrence of ice saturation; this condition of high relative humidity is supported by downwelling of a large amount of water vapor in an intense temperature inversion layer and an extremely small number of ice nuclei, suggested by in-situ data. An improved correction applied to a vertical profile in the temperature inversion layer reveals that supersaturation with respect to ice appears at all levels. In the lowest layer, humidity increases with decreasing height, although observed data show steep dryness with decreasing height. This is considered a measurement error

Establishment of Unmanned aerial vehicle systems for Earth system sciences in the polar region

The Tenth Symposium on Polar Science/Special session: [S] Future plan of Antarctic research: Towards phase X of the Japanese Antarctic Research Project (2022-2028) and beyond, Tue. 3 Dec. / Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

Meteorological characteristics of Antarctic inland station, Dome Fuji (scientific paper)

Surface meteorological observations were carried out during 1995 and 1997, and extended atmospheric science observations were carried out in 1997 as a sub program of "Atmospheric Circulation and Material Cycle in the Antarctic (1997-2001)" at Dome Fuji Station (77°19\u27S, 39°42\u27E) where deep ice core drilling was done. The annual mean surface air temperature was -54.4°C with the lowest record of -79.7°C. The mean wind speed was 5.8 m/s with no clear prevailing wind direction. From aerological soundings, temperature profiles are described; they are characterized by a strong surface inversion such as 25°C, on a normal winter day. Abrupt warming occurred several times a year; the largest showed 40 degree temperature increase within two days between 17 and 19 July 1997. The event was associated with the intrusion of an anticyclone, "a blocking high", and many drastic phenomena such as large accumulation of snow followed this event

1997ネン シュンキ ニ ナンキョク ショウワキチ ニ オイテ ハツゲンシタ チジョウ オゾン キュウゲン ゲンショウ

1997年8月に南極昭和基地において発現した地上オゾン急減現象(以下,SOD)は約1日継続した.地上オゾン濃度は,SODの前後では30 ppbv程度であったものが,SOD期間中には3 ppbvから0.1 ppbvにまで減少した.オゾン濃度が低下している間は,地上付近のエアロゾルの全ての粒径(0.01 μm以上～ 5.0 μm以上)において,数濃度が一桁程度高い状態が維持されていた.SODの開始と終了時期のオゾン濃度とエアロゾル濃度の時間変化は急激で,SODに関連した気団の境界が明瞭であったと考えられる.SOD期間の昭和基地上空では,3000 m付近まで湿度の高い層が観測された.SOD終了直後に実施したオゾンゾンデ観測では,高度3000 m付近までオゾン濃度の低い空気層が観測された.SODは,トラフに伴う前線が昭和基地を通過後に発現した.米国NOAAの衛星雲画像及び空気塊のバックワードトラジェクトリー解析の結果,SODをもたらした大気は,ウェッデル海域の地上付近の大気が東方へ輸送され,前線の西側に位置していたものと考えられる.1997-2008年の12年間に発現した28回のSODを抽出して比較した結果,本稿で対象とした1997年8月28-29日のSODが,1997-2008年の内で,その継続期間及び期間中のオゾン最低濃度において,他のSODと比較して最も顕著なものであったことがわかった.Surface ozone concentration decreased dramatically from 28 to 29 August 1997 at Syowa Station, Antarctica. Aerosol concentrations with diameters of 0.01-5.0 μm increased to several times as much as background concentrations, accompanied with the surface ozone depletion. Air mass above Syowa Station in SOD events had high humidity and low ozone concentration. The SOD also accompanied change of wind direction, and the results of backward trajectory analysis suggested that this air mass was transported from the westerly sea ice area of a cold front within several days. These results suggested that the SOD on 28 29 August 1997 at Syowa Station occurred by transport of the air mass

Antarctic Study on Tropospheric Aerosol and Snow Chemistry (ASTASC) in JARE Phase X

The Tenth Symposium on Polar Science/Special session: [S] Future plan of Antarctic research: Towards phase X of the Japanese Antarctic Research Project (2022-2028) and beyond, Tue. 3 Dec. / Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

ショウワキチ ト ドームフジキチ ニ オケル エアロゾル リュウケイ ブンプ ノ ツウネン カンソク

1997年2月～1998年1月に,昭和基地(69゜00′S,39゜35′E,15 m a.s.l.)及びドームふじ観測拠点(77゜19′S,39゜42′E,3810 m a.s.l.)において,直径0.003-5 μmのエアロゾル粒径分布の変動の観測を行った.両基地において小エイトケンモード(直径0.05 μm以下),大エイトケンモード(直径0.05-0.3 μm),大粒子・粗大粒子モード(直径0.3 μm以上)の3つのモードが認められた.小エイトケンモードおよび大エイトケンモードは,夏に高濃度,冬に低濃度となり,一方,大粒子・巨大粒子モードは夏に低濃度,冬に高濃度となった.1～数日の時間スケールの全粒径にわたる急増,急減現象が両基地で冬季に見られた.ドームふじ観測拠点では春季に小エイトケン粒子のみの急増も見られた.ドームふじ観測拠点においてこれらの現象が起こる気象条件は,昭和基地における類似の現象が起こる時の気象条件とは異なっていた.Simultaneous observations of the aerosol size distribution for diameters of 0.003-5.0 μm were performed at Syowa Station (69゜00′S, 39゜35′E, 15 m a.s.l.) and Dome Fuji Station (77゜19′S, 39゜42′E, 3810 m a.s.l.) in Antarctica from February 1997 to January 1998. Size distributions show composites of a small-Aitken mode (less than 0.05 μm in diameter), a large-Aitken mode (0.05-0.3 μm in diameter), and a large giant particle mode (larger than 0.3 μm in diameter). Concentrations of small and large Aitken modes were high in summer and low in winter. On the other hand, concentrations of large giant particle mode were low in summer and high in winter. The high and or low concentration events for one or a few days in whole size range were observed especially in winter. High concentration events in small Aitken mode with the low concentrations in diameter of 0.07-5.0 μm were also observed at Dome Fuji Station in spring. Meteorological conditions during the events at Dome Fuji Station were different from those at at Syowa station

Long-term field experiment for detection and study of climate change in East Antarctica

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　統計数理研究所 セミナー室2（D304

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)