T. Yamanouchi - Academia.edu (original) (raw)
Papers by T. Yamanouchi
From Pole to Pole, 2010
The visionaries and advocates of four different international years the elec-tronic Geophysic... more The visionaries and advocates of four different international years the elec-tronic Geophysical Year (eGY), the International Heliophysical Year (IHY), the International Polar Year (IPY) and the International Year of Planet Earth (IYPE) all recognized the approach of 2007 and ...
Tellus B, 2003
Systematic collections of stratospheric air samples have been conducted over Japan since 1985 usi... more Systematic collections of stratospheric air samples have been conducted over Japan since 1985 using a balloon-borne cryogenic sampler. The collection of stratospheric air samples was also carried out twice over Scandinavia and once over Antarctica. Vertical profiles of CO 2 concentration thus obtained over these locations were quite similar to each other; CO 2 concentration decreased with increasing altitude in the lower stratosphere and reached an almost constant value in the mid-stratosphere. δ 13 C of stratospheric CO 2 observed over these locations enriched with increasing altitude. A negative correlation between δ 13 C and CO 2 concentration with δ 13 C/ CO 2 of −0.02‰ ppmv −1 was found in the lower stratosphere. Although CO 2 concentration was almost constant in the mid-stratosphere, the δ 13 C enrichment was observed in succession. δ 18 O of stratospheric CO 2 also enriched with increasing altitude. The enrichment was significant; δ 18 O was almost 0‰ at the tropopause and reached a maximum value of about 11‰ at a layer with N 2 O concentration of about 10 ppbv. A compact relation between δ 18 O and N 2 O concentration was consistently observed for these locations. Stratosperic CO 2 over Japan showed a secular increase with an average rate of 1.4 ppmv yr −1 for the period 1985-2000. The secular increase was not constant with time, and temporal stagnation of the CO 2 increase was observed in 1997.
Journal of Geophysical Research, 2007
Large sets of filtered actinometer, filtered pyrheliometer and Sun photometer measurements have b... more Large sets of filtered actinometer, filtered pyrheliometer and Sun photometer measurements have been carried out over the past 30 years by various groups at different Arctic and Antarctic sites and for different time periods. They were examined to estimate ensemble average, long-term trends of the summer background aerosol optical depth AOD(500 nm) in the polar regions (omitting the data influenced by Arctic haze and volcanic eruptions). The trend for the Arctic was estimated to be between À1.6% and À2.0% per year over 30 years, depending on location. No significant trend was observed for Antarctica. The time patterns of AOD(500 nm) and Å ngström's parameters a and b measured with Sun photometers during the last 20 years at various Arctic and Antarctic sites are also presented. They give a measure of the large variations of these parameters due to El Chichon, Pinatubo, and Cerro Hudson volcanic particles, Arctic haze episodes most frequent in winter and spring, and the transport of Asian dust and boreal smokes to the Arctic region. Evidence is also shown of marked differences between the aerosol optical parameters measured at coastal and high-altitude sites in Antarctica. In situ optical and chemical composition parameters of aerosol particles measured at Arctic and Antarctic sites are also examined to achieve more complete information on the multimodal size distribution shape parameters and their radiative properties. A characterization of aerosol radiative parameters is also defined by plotting the daily mean values of a as a function of AOD(500 nm), separately for the two polar regions, allowing the identification of different clusters related to fifteen aerosol classes, for which the spectral values of complex refractive index and single scattering albedo were evaluated.
Antarctic Science, 2009
The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual,... more The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual, and is closely coupled to other parts of the global climate system. We review these variations from the perspective of the geological and glaciological records and the recent historical period from which we have instrumental data (∼the last 50 years). We consider their consequences for the biosphere, and show how the latest numerical models project changes into the future, taking into account human actions in the form of the release of greenhouse gases and chlorofluorocarbons into the atmosphere. In doing so, we provide an essential Southern Hemisphere companion to the Arctic Climate Impact Assessment.
Journal of the Atmospheric Sciences, 2009
The horizontal structure of processes causing increases in ozone in the Antarctic polar vortex wa... more The horizontal structure of processes causing increases in ozone in the Antarctic polar vortex was examined using data measured in 2003 from an ozonesonde observation campaign at Syowa Station (39.6°E, 69.0°S) and from the Improved Limb Atmospheric Spectrometer II (ILAS-II) onboard the Advanced Earth Observing Satellite II. The ILAS-II data are daily and distributed uniformly at 14 points in the zonal direction, mostly at polar latitudes. The Antarctic ozone hole that developed in 2003 was one of the largest recorded. The period of focus in this study is 26 September through 24 October, when a strong polar vortex was situated in the stratosphere. An ozone mixing ratio contour (1.0 ppmv) moved downward near a height of 20 km during the period of focus. This increase in ozone is likely to result from downward transport of ozone-rich air originating from lower latitudes by Brewer–Dobson circulation. First, the descent rate of the mixing ratio contour was estimated by taking the geometr...
Journal of Geophysical Research, 2010
During our aerosol measurement program at Syowa Station, Antarctica, in 2004-2007, some low-visib... more During our aerosol measurement program at Syowa Station, Antarctica, in 2004-2007, some low-visibility (haze) phenomena were observed during winter-spring under conditions with low winds and without drifting snow and fog. During "Antarctic haze" phenomena, the number concentration of aerosol particles and black carbon concentration increased by 1 to 2 orders higher relative to background conditions at Syowa Station, whereas surface O 3 concentration dropped simultaneously, especially after polar sunrise. Chemical analysis showed that major aerosol constituents in the haze phenomena were sea salt (e.g., Na + , Cl −). Trajectory analysis and the Navy Aerosol Analysis and Prediction System model showed that plumes from biomass burning in South America and southern Africa were transported to Syowa Station, on the Antarctic coast, because of the eastward (occasionally westward) approach of cyclones in the Southern Ocean and subsequent poleward flow. This poleward flow from midlatitudes of the plume and injection of seasalt particles during the transport might engender Antarctic haze phenomena at Syowa Station. Differences of O 3 concentration between the background and the haze conditions tended to be larger in spring (after polar sunrise) than in winter. Enhancement of sea-salt particles in the haze events can serve important roles in providing additional sources of reactive halogen species.
Are the Arctic and Antarctic really warming now? This review was performed in order to answer thi... more 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 midlatitudes. Much current research is focused on the effect of Arctic warming on mid-latitude weather, with the aim of increasing our understanding ...
From Pole to Pole, 2010
The visionaries and advocates of four different international years the elec-tronic Geophysic... more The visionaries and advocates of four different international years the elec-tronic Geophysical Year (eGY), the International Heliophysical Year (IHY), the International Polar Year (IPY) and the International Year of Planet Earth (IYPE) all recognized the approach of 2007 and ...
Tellus B, 2003
Systematic collections of stratospheric air samples have been conducted over Japan since 1985 usi... more Systematic collections of stratospheric air samples have been conducted over Japan since 1985 using a balloon-borne cryogenic sampler. The collection of stratospheric air samples was also carried out twice over Scandinavia and once over Antarctica. Vertical profiles of CO 2 concentration thus obtained over these locations were quite similar to each other; CO 2 concentration decreased with increasing altitude in the lower stratosphere and reached an almost constant value in the mid-stratosphere. δ 13 C of stratospheric CO 2 observed over these locations enriched with increasing altitude. A negative correlation between δ 13 C and CO 2 concentration with δ 13 C/ CO 2 of −0.02‰ ppmv −1 was found in the lower stratosphere. Although CO 2 concentration was almost constant in the mid-stratosphere, the δ 13 C enrichment was observed in succession. δ 18 O of stratospheric CO 2 also enriched with increasing altitude. The enrichment was significant; δ 18 O was almost 0‰ at the tropopause and reached a maximum value of about 11‰ at a layer with N 2 O concentration of about 10 ppbv. A compact relation between δ 18 O and N 2 O concentration was consistently observed for these locations. Stratosperic CO 2 over Japan showed a secular increase with an average rate of 1.4 ppmv yr −1 for the period 1985-2000. The secular increase was not constant with time, and temporal stagnation of the CO 2 increase was observed in 1997.
Journal of Geophysical Research, 2007
Large sets of filtered actinometer, filtered pyrheliometer and Sun photometer measurements have b... more Large sets of filtered actinometer, filtered pyrheliometer and Sun photometer measurements have been carried out over the past 30 years by various groups at different Arctic and Antarctic sites and for different time periods. They were examined to estimate ensemble average, long-term trends of the summer background aerosol optical depth AOD(500 nm) in the polar regions (omitting the data influenced by Arctic haze and volcanic eruptions). The trend for the Arctic was estimated to be between À1.6% and À2.0% per year over 30 years, depending on location. No significant trend was observed for Antarctica. The time patterns of AOD(500 nm) and Å ngström's parameters a and b measured with Sun photometers during the last 20 years at various Arctic and Antarctic sites are also presented. They give a measure of the large variations of these parameters due to El Chichon, Pinatubo, and Cerro Hudson volcanic particles, Arctic haze episodes most frequent in winter and spring, and the transport of Asian dust and boreal smokes to the Arctic region. Evidence is also shown of marked differences between the aerosol optical parameters measured at coastal and high-altitude sites in Antarctica. In situ optical and chemical composition parameters of aerosol particles measured at Arctic and Antarctic sites are also examined to achieve more complete information on the multimodal size distribution shape parameters and their radiative properties. A characterization of aerosol radiative parameters is also defined by plotting the daily mean values of a as a function of AOD(500 nm), separately for the two polar regions, allowing the identification of different clusters related to fifteen aerosol classes, for which the spectral values of complex refractive index and single scattering albedo were evaluated.
Antarctic Science, 2009
The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual,... more The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual, and is closely coupled to other parts of the global climate system. We review these variations from the perspective of the geological and glaciological records and the recent historical period from which we have instrumental data (∼the last 50 years). We consider their consequences for the biosphere, and show how the latest numerical models project changes into the future, taking into account human actions in the form of the release of greenhouse gases and chlorofluorocarbons into the atmosphere. In doing so, we provide an essential Southern Hemisphere companion to the Arctic Climate Impact Assessment.
Journal of the Atmospheric Sciences, 2009
The horizontal structure of processes causing increases in ozone in the Antarctic polar vortex wa... more The horizontal structure of processes causing increases in ozone in the Antarctic polar vortex was examined using data measured in 2003 from an ozonesonde observation campaign at Syowa Station (39.6°E, 69.0°S) and from the Improved Limb Atmospheric Spectrometer II (ILAS-II) onboard the Advanced Earth Observing Satellite II. The ILAS-II data are daily and distributed uniformly at 14 points in the zonal direction, mostly at polar latitudes. The Antarctic ozone hole that developed in 2003 was one of the largest recorded. The period of focus in this study is 26 September through 24 October, when a strong polar vortex was situated in the stratosphere. An ozone mixing ratio contour (1.0 ppmv) moved downward near a height of 20 km during the period of focus. This increase in ozone is likely to result from downward transport of ozone-rich air originating from lower latitudes by Brewer–Dobson circulation. First, the descent rate of the mixing ratio contour was estimated by taking the geometr...
Journal of Geophysical Research, 2010
During our aerosol measurement program at Syowa Station, Antarctica, in 2004-2007, some low-visib... more During our aerosol measurement program at Syowa Station, Antarctica, in 2004-2007, some low-visibility (haze) phenomena were observed during winter-spring under conditions with low winds and without drifting snow and fog. During "Antarctic haze" phenomena, the number concentration of aerosol particles and black carbon concentration increased by 1 to 2 orders higher relative to background conditions at Syowa Station, whereas surface O 3 concentration dropped simultaneously, especially after polar sunrise. Chemical analysis showed that major aerosol constituents in the haze phenomena were sea salt (e.g., Na + , Cl −). Trajectory analysis and the Navy Aerosol Analysis and Prediction System model showed that plumes from biomass burning in South America and southern Africa were transported to Syowa Station, on the Antarctic coast, because of the eastward (occasionally westward) approach of cyclones in the Southern Ocean and subsequent poleward flow. This poleward flow from midlatitudes of the plume and injection of seasalt particles during the transport might engender Antarctic haze phenomena at Syowa Station. Differences of O 3 concentration between the background and the haze conditions tended to be larger in spring (after polar sunrise) than in winter. Enhancement of sea-salt particles in the haze events can serve important roles in providing additional sources of reactive halogen species.
Are the Arctic and Antarctic really warming now? This review was performed in order to answer thi... more 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 midlatitudes. Much current research is focused on the effect of Arctic warming on mid-latitude weather, with the aim of increasing our understanding ...