North-south contrast in radiative forcing due to warm-moist air intrusion into the polar regions

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Researc

極域温暖化問題の概観

今，北極・南極は温暖化しているのだろうか？　この質問に答えられるように，解説を試みた．近年の地球温暖化の中で，強い温暖化の現れている地域は北極域と南極半島域である．北極域の温暖化は全球平均の2倍以上の温暖化で，北極海の夏の海氷も著しく減少している．何がこの北極温暖化増幅をもたらしているのか，その原因を探った．一方，南極では，南極半島や西南極で温暖化が激しいのに対し，東南極では温暖化が顕著にはみえない．なぜ，温暖化が抑えられているのであろうか．オゾンホールが関係しているという説を述べる．さらに，北極温暖化の影響で，中緯度に寒冷化が起こる現象がみつけられ，様々な議論を呼んでいる．今後の研究が期待される．Are the Arctic and Antarctic really warming now? This review was performed in order to answer this question. In the recent, the strongest warming occurred in the Arctic and Antarctic Peninsula under the global warming. Warming in the Arctic is more than twice the global average, and sea ice has rapidly reduced in summer. A contribution of each processes have been investigated to determine which play the largest role in this Arctic warming amplification. On the other hand, despite strong warming in the Antarctic Peninsula and West Antarctica, no meaningful warming has been seen in East Antarctica. What is the reason for this suppressed warming in East Antarctica? There has been some speculation that the ozone hole has been working as a suppressor of warming. Another effect of the Arctic warming is its influence on extreme weather in the mid-latitudes. Much current research is focused on the effect of Arctic warming on mid-latitude weather, with the aim of increasing our understanding of interaction between these regions

Temperature dependence of brightness temperature difference of AVHRR infrared split window channels in the Antarctic

One method to identify clouds from NOAA/AVHRR data is to use the difference in brightness temperature of infrared split window channels in the 10μm region. Under the low temperature over the Antarctic continent in winter, it is necessary to detect a slight difference in brightness temperature. In this paper, we investigate the temperature dependence of the brightness temperature difference of channel 4 (10.8μm) brightness temperature (T4), and channel 5 (12 μm) brightness temperature (T5) (T4-T5) of a cloud free scene. T4-T5 is about 0°C at low temperature around -80°C, and gradually increases up to a high of 1°C at high temperature around 0°C. The rates of increase in T4-T5 were almost constant for T4 lower than -40°C. For T4 higher than -30°C, T4-T5 remains almost unchanged. For T4 between -40°C and -30°C, T4-T5 increases rapidly. In order to explain this temperature dependence, the contribution of water vapor and surface emissivity to the difference in brightness temperature was calculated from in situ data using the radiation code MODTRAN. The result is shown below. About the contribution of water vapor, at T4 lower than -25°C, T4-T5 was nearly zero. From about -25°C to 0°C of T4, T4-T5 increases up to near 0.6°C. On the other hand, when the surface emissivity difference between CH4 and CH5 was set to 0.01, T4-T5 increased in all temperature ranges. The rate of increase was almost constant. In the temperature range lower than -40°C, T4-T5 conformed to T4-T5 of satellite data

Airborne microorganisms in the indoor environment of Syowa Station in Antarctica

Airborne bacterial and fungal numbers in the buildings of Syowa Station in Antarctica were examined for 9 months in 2001. The number of bacteria or fungi was less than 20 or 70/m^3 in the dining room and washroom. The average number of bacteria or fungi was less than 1/50 or 1/5 of those in Japan and Europe, respectively, and remained constant regardless of season. The number of airborne microorganisms appeared to depend on drying of the indoor environment by the use of air-conditioners

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