The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Koji Shimada - One of the best experts on this subject based on the ideXlab platform.

  • Vertical double silicate maxima in the sea-ice Reduction Region of the western Arctic Ocean: Implications for an enhanced biological pump due to sea-ice Reduction
    Journal of Oceanography, 2009
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Sanae Chiba
    Abstract:

    The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 (Mirai04) over wide east-west ranges from Alaska to eastern Siberia, where sea-ice cover has been greatly reduced in recent summers. The obtained data reveal differences in silicate profiles between shelf slope areas east and west of the Chukchi Plateau, the ridge that divides the Canada Basin into the Alaskan and east Siberian sides. East of the plateau, a single silicate maximum was found in a layer of Pacific-origin winter water, as examined in many previous studies. In contrast, west of the plateau, we found vertical double silicate maxima, which are reported for the first time in this study. The shallower silicate maximum corresponded to an N** minimum, signaling denitrification at the shelf bottom. This suggests that the shallower silicate maximum was caused by the spreading of shelf water. In contrast, the deeper silicate maximum corresponded to an oxygen minimum and a maximum silicate/phosphate ratio (Si/P), suggesting that this deeper maximum resulted from the decomposition of opal-shelled organisms. We also compared a silicate profile from Mirai04 to aprofile from the Arctic Ocean Section 94 (AOS94) expedition of 1994, a heavy ice year. The results suggest that sea-ice loss has enhanced biological activities, likely resulting in the appearance of the deeper silicate maximum.

  • East–west differences in water mass, nutrient, and chlorophyll a distributions in the sea ice Reduction Region of the western Arctic Ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamoto-kawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

  • east west differences in water mass nutrient and chlorophyll a distributions in the sea ice Reduction Region of the western arctic ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamotokawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

  • Scenario study for a Regional low-carbon society
    Sustainability Science, 2007
    Co-Authors: Kei Gomi, Koji Shimada, Yuzuru Matsuoka, Masaaki Naito
    Abstract:

    Japan should undertake drastic greenhouse gas (GHG) emission Reductions by the middle of this century in order to mitigate climate change problems. Municipalities should design and execute scenarios toward a low-carbon society suited to their respective Regions. This study describes long-term future visions developed for Shiga Prefecture targeting CO_2 emission Reductions of 30–50% by 2030, and presents scenarios to attain these targets, which are achievable with mild economic growth. For targets over a 30% Reduction, Region-specific measures including land-use reform and citizen behavioral changes are necessary. Compared with other Regions in Japan, Shiga should give priority to a modal shift in transport, efficiency improvements in industry, and photovoltaic energy generation.

Sanae Chiba - One of the best experts on this subject based on the ideXlab platform.

  • Vertical double silicate maxima in the sea-ice Reduction Region of the western Arctic Ocean: Implications for an enhanced biological pump due to sea-ice Reduction
    Journal of Oceanography, 2009
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Sanae Chiba
    Abstract:

    The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 (Mirai04) over wide east-west ranges from Alaska to eastern Siberia, where sea-ice cover has been greatly reduced in recent summers. The obtained data reveal differences in silicate profiles between shelf slope areas east and west of the Chukchi Plateau, the ridge that divides the Canada Basin into the Alaskan and east Siberian sides. East of the plateau, a single silicate maximum was found in a layer of Pacific-origin winter water, as examined in many previous studies. In contrast, west of the plateau, we found vertical double silicate maxima, which are reported for the first time in this study. The shallower silicate maximum corresponded to an N** minimum, signaling denitrification at the shelf bottom. This suggests that the shallower silicate maximum was caused by the spreading of shelf water. In contrast, the deeper silicate maximum corresponded to an oxygen minimum and a maximum silicate/phosphate ratio (Si/P), suggesting that this deeper maximum resulted from the decomposition of opal-shelled organisms. We also compared a silicate profile from Mirai04 to aprofile from the Arctic Ocean Section 94 (AOS94) expedition of 1994, a heavy ice year. The results suggest that sea-ice loss has enhanced biological activities, likely resulting in the appearance of the deeper silicate maximum.

  • East–west differences in water mass, nutrient, and chlorophyll a distributions in the sea ice Reduction Region of the western Arctic Ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamoto-kawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

  • east west differences in water mass nutrient and chlorophyll a distributions in the sea ice Reduction Region of the western arctic ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamotokawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

Shigeto Nishino - One of the best experts on this subject based on the ideXlab platform.

  • Vertical double silicate maxima in the sea-ice Reduction Region of the western Arctic Ocean: Implications for an enhanced biological pump due to sea-ice Reduction
    Journal of Oceanography, 2009
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Sanae Chiba
    Abstract:

    The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 (Mirai04) over wide east-west ranges from Alaska to eastern Siberia, where sea-ice cover has been greatly reduced in recent summers. The obtained data reveal differences in silicate profiles between shelf slope areas east and west of the Chukchi Plateau, the ridge that divides the Canada Basin into the Alaskan and east Siberian sides. East of the plateau, a single silicate maximum was found in a layer of Pacific-origin winter water, as examined in many previous studies. In contrast, west of the plateau, we found vertical double silicate maxima, which are reported for the first time in this study. The shallower silicate maximum corresponded to an N** minimum, signaling denitrification at the shelf bottom. This suggests that the shallower silicate maximum was caused by the spreading of shelf water. In contrast, the deeper silicate maximum corresponded to an oxygen minimum and a maximum silicate/phosphate ratio (Si/P), suggesting that this deeper maximum resulted from the decomposition of opal-shelled organisms. We also compared a silicate profile from Mirai04 to aprofile from the Arctic Ocean Section 94 (AOS94) expedition of 1994, a heavy ice year. The results suggest that sea-ice loss has enhanced biological activities, likely resulting in the appearance of the deeper silicate maximum.

  • East–west differences in water mass, nutrient, and chlorophyll a distributions in the sea ice Reduction Region of the western Arctic Ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamoto-kawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

  • east west differences in water mass nutrient and chlorophyll a distributions in the sea ice Reduction Region of the western arctic ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamotokawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

Motoyo Itoh - One of the best experts on this subject based on the ideXlab platform.

  • Vertical double silicate maxima in the sea-ice Reduction Region of the western Arctic Ocean: Implications for an enhanced biological pump due to sea-ice Reduction
    Journal of Oceanography, 2009
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Sanae Chiba
    Abstract:

    The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 (Mirai04) over wide east-west ranges from Alaska to eastern Siberia, where sea-ice cover has been greatly reduced in recent summers. The obtained data reveal differences in silicate profiles between shelf slope areas east and west of the Chukchi Plateau, the ridge that divides the Canada Basin into the Alaskan and east Siberian sides. East of the plateau, a single silicate maximum was found in a layer of Pacific-origin winter water, as examined in many previous studies. In contrast, west of the plateau, we found vertical double silicate maxima, which are reported for the first time in this study. The shallower silicate maximum corresponded to an N** minimum, signaling denitrification at the shelf bottom. This suggests that the shallower silicate maximum was caused by the spreading of shelf water. In contrast, the deeper silicate maximum corresponded to an oxygen minimum and a maximum silicate/phosphate ratio (Si/P), suggesting that this deeper maximum resulted from the decomposition of opal-shelled organisms. We also compared a silicate profile from Mirai04 to aprofile from the Arctic Ocean Section 94 (AOS94) expedition of 1994, a heavy ice year. The results suggest that sea-ice loss has enhanced biological activities, likely resulting in the appearance of the deeper silicate maximum.

  • East–west differences in water mass, nutrient, and chlorophyll a distributions in the sea ice Reduction Region of the western Arctic Ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamoto-kawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

  • east west differences in water mass nutrient and chlorophyll a distributions in the sea ice Reduction Region of the western arctic ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamotokawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.

Michiyo Yamamotokawai - One of the best experts on this subject based on the ideXlab platform.

  • east west differences in water mass nutrient and chlorophyll a distributions in the sea ice Reduction Region of the western arctic ocean
    Journal of Geophysical Research, 2008
    Co-Authors: Shigeto Nishino, Koji Shimada, Motoyo Itoh, Michiyo Yamamotokawai, Sanae Chiba
    Abstract:

    [1] The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 across a front between cold Arctic water and warm water from the Pacific Ocean where sea ice cover has been largely reduced in recent summers. The hydrographic data indicate a new type of vertical temperature minimum water west of the front along isohaline surfaces with approximate salinity (S) of 32, which is fresher than the typical temperature minimum (S ≈ 33) caused by spreading of Pacific winter water (PWW) mainly to the east of the front. Both of the temperature minimum waters are characterized by low potential vorticity with near-freezing temperature, suggesting that they are formed by winter convection with sea ice formation. A difference between the waters results from a large contribution of sea ice meltwater to the fresh temperature minimum (frTmin) water of S ≈ 32. The distributions of the sea ice meltwater contribution and nitrogen deficit suggest that summer shelf water, largely influenced by the sea ice melt in the Chukchi Sea, is modified by winter convection on its way to the Chukchi Abyssal Plain to form the frTmin water. This water supplies nutrients through the water distribution to the west of the front at depths shallower than the nutrient maximum layer caused by the PWW spreading. The shallower nutrient supply by the frTmin water combined with light penetration without sea ice cover could produce a prominent chlorophyll a maximum layer west of the front.