The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform

K Mursula - One of the best experts on this subject based on the ideXlab platform.

  • Annual Variation in near earth solar wind speed evidence for persistent north south asymmetry related to solar magnetic polarity
    Geophysical Research Letters, 1998
    Co-Authors: B Zieger, K Mursula
    Abstract:

    We study the Annual Variation in solar wind speed at Earth's orbit and in geomagnetic activity since mid-1960's. The two parameters depict a very similar Annual Variation during the whole period. Annual Variation has maximum amplitude around sunspot minima. The phase of Annual Variation reverses soon after solar maxima, following the Sun's polarity reversal and indicating a new type of 22-year periodicity. Stronger solar wind is found at or close to the Earth's highest northern (southern, resp.) heliographic latitudes during solar minima with a negative (positive) magnetic polarity. This implies an asymmetric SW speed distribution across heliographic equator such that the minimum speed region during solar minimum times is displaced away from heliographic equator towards the northern magnetic hemisphere. This may result e.g. from a systematically larger extension of polar coronal holes from the Sun's magnetic south pole toward solar equator. We exclude the earlier explanations proposed for Annual Variation, such as accumulation of small comets within 1 AU, or internal solar Variation.

Martijn Arns - One of the best experts on this subject based on the ideXlab platform.

  • Annual Variation in attentional response after methylphenidate treatment
    European Child & Adolescent Psychiatry, 2019
    Co-Authors: Madelon Aimee Vollebregt, Tom Deboer, Donna Palmer, Evian Gordon, Kamran Fallahpour, J. Leon Kenemans, Jan K. Buitelaar, Sean W. Cain, Glen R. Elliott, Martijn Arns
    Abstract:

    Prevalence rates of attention-deficit/hyperactivity disorder (ADHD) differ with geographical areas varying in sunlight intensity. Sun- or daylight reaching the retina establishes entrainment of the circadian clock to daylight. Changes herein, hence, alterations in clock alignment, could be reflected indirectly in inattention via sleep duration. We here studied (1) Annual Variation in inattention at treatment initiation; (2) Annual Variation in response to ADHD treatment [methylphenidate (MPH)] by day of treatment initiation; and (3) dose dependence. We predicted least baseline inattention during a period of high sunlight intensity implying more room for improvement (i.e., a better treatment response) when sunlight intensity is low. These hypotheses were not confirmed. High-dose treated patients, however, had significantly better attention after treatment than low-dosed treated patients, only when treated in the period from winter to summer solstice. Change in solar irradiance (SI) during low-dosed treatment period was negatively related to attentional improvement. The above described findings were primarily found in inattention ratings and replicated in omission errors on a continuous performance task. Daylight and inattention have been proposed to be related via mediation of the circadian system. One mechanism of MPH may be to enhance sensitivity to the diurnal entrainment to sunlight and the question can be raised whether appropriate lighting could potentiate the effects of stimulants.

  • Annual Variation in attentional response after Methylphenidate treatment
    2019
    Co-Authors: Madelon Aimee Vollebregt, Leon Kenemans, Jan Buitelaar, Tom Deboer, Sean Cain, Donna Palmer, Glen Elliott, Evian Gordon, Kamran Fallahpour, Martijn Arns
    Abstract:

    Prevalence rates of Attention-Deficit/Hyperactivity Disorder (ADHD) differ with geographical areas varying in sunlight intensity. We here studied 1) Annual Variation in inattention at treatment initiation; 2) Annual Variation in response to ADHD treatment [Methylphenidate (MPH)] by day of treatment initiation; and 3) dose-dependency. We predicted least baseline inattention during a period of high sunlight intensity implying more room for improvement (i.e., a better treatment response) when sunlight intensity is low. These hypotheses were not confirmed. High dose treated patients however had significantly better attention than low dosed treated patients, only when treated in the period from winter to summer solstice. Change in solar irradiance (SI) during treatment period was negatively related to attentional improvement. The above described findings were primarily found in inattention ratings and replicated in omission errors on a Continuous Performance Task. Daylight and inattention have been proposed to be related via mediation of the circadian system. One mechanism of MPH may be to enhance sensitivity to the diurnal entrainment to sunlight and the question can be raised whether appropriate lighting could potentiate the effects of stimulants.

Yasuhiro Yamanaka - One of the best experts on this subject based on the ideXlab platform.

  • An Improved Estimation of the Poleward Expansion of Coral Habitats Based on the Inter-Annual Variation of Sea Surface Temperatures
    Coral Reefs, 2015
    Co-Authors: Shintaro Takao, Hiroya Yamano, Kaoru Sugihara, Naoki H. Kumagai, Masahiko Fujii, Yasuhiro Yamanaka
    Abstract:

    The poleward expansion of coral habitats has been observed along the Japanese coast since the 1930s. Previous modeling studies have projected a poleward expansion using decadal-mean sea surface temperatures (SSTs) in the coldest months. However, this poleward expansion could be affected by the inter-Annual Variation of SST in the coldest months, which has not been considered before. In this study, the simulated pattern of poleward expansion was compared between cases where coral mortality was considered based on the inter-Annual Variation of SST and the decadal-mean SST in the coldest months. Modeled monthly mean SSTs for historical and future global warming simulations from the most recent climate projection model (MIROC4h) were used. The poleward expansion of corals simulated by considering mortality based on the inter-Annual Variation of SST in the coldest months better reproduced the observed poleward expansion speed compared to the simulations without such a consideration. Our results show the importance of considering coral mortality based on the inter-Annual Variation of seawater temperature to produce a more realistic poleward expansion of coral habitats.

Tsing-chang Chen - One of the best experts on this subject based on the ideXlab platform.

  • Annual Variation of midlatitude precipitation
    Journal of Climate, 2004
    Co-Authors: Tsing-chang Chen, Wan Ru Huang, Eugene S. Takle
    Abstract:

    Abstract Annual Variation of midlatitude precipitation and its maintenance through divergent water vapor flux were explored by the use of hydrological variables from three reanalyses [(NCEP–NCAR, ECMWF Re-Analysis (ERA), and Goddard Earth Observing System (GEOS-1)] and two global precipitation datasets [Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) and Global Precipitation Climatology Project (GPCP)]. Two Annual Variation patterns of midlatitude precipitation were identified: Tropical–midlatitude precipitation contrast: Midlatitude precipitation along storm tracks over the oceans attains its maximum in winter and its minimum in summer opposite to that over the tropical continents. Land–ocean precipitation contrast: The Annual precipitation Variation between the oceans and the continent masses exhibits a pronounced seesaw. The Annual Variation of precipitation along storm tracks of both hemispheres follows that of the convergence of transient water vapor flux. On the other hand, t...

  • Annual Variation of Surface Pressure on a High East Asian Mountain and Its Surrounding Low Areas
    Journal of Climate, 1999
    Co-Authors: Tsing-chang Chen, Ming-cheng Yen
    Abstract:

    Abstract An inverse Annual Variation is observed between surface pressure on the highest mountain, which has an elevation of approximately 4000 m, and in the lowlands of Taiwan (a subtropical island in east Asia). This inverse Annual Variation in surface pressure of high and low elevation in low latitudes reflects, essentially, a vertical phase reversal of the tropical circulation, which is illustrated with the Annual Variation in the vertical structure of tropical geopotential height.

  • Annual Variation of the global precipitable water and its maintenance: observation and climate-simulation
    Tellus A: Dynamic Meteorology and Oceanography, 1996
    Co-Authors: Tsing-chang Chen, Ming-cheng Yen, James Pfaendtner, Y. C. Sud
    Abstract:

    The Annual Variation of the global-mean precipitable water 〈W〉and the associated hydrological cycle were analyzed with the upper-air data generated by the Global Data Assimilation System of the National Meteorological Center for 1981–1991 and the European Centre for Medium Range Weather Forecasts from 1983–1991. It was found that the Annual Variation of 〈W〉 coincides with that of the Northern Hemisphere precipitable water [W]NH. The hemispheric-mean ([ ]) water budget analysis shows that water vapor is transported from the winter to the summer hemisphere across the equator by the Hadley circulation, and that the Annual Variations in the water vapor sink [P – E] for both hemispheres also follow the same seasonal march. The amplitudes of the Annual Variations in these two hydrological processes are comparable in both hemispheres. Thus, the Annual Variations of [W]NH and [W]SH are the result of slight imbalances between the cross-equator water vapor transport and the water vapor sink, particularly in the spring and fall. The climatological hemispheric-mean water budgets reveal that the Southern Hemisphere is a water vapor source and the Northern Hemisphere is a water vapor sink. The cross-equator water vapor transport constitutes a major source acting to maintain [W]NH, and in turn 〈W〉. The hydrological mechanism maintaining the observed 〈W〉 Annual Variation is consistent with that obtained from the hydrological cycle in a 10-year (1979–1988) climate simulation done at the Goddard Laboratory for Atmospheres as part of their participation in the Atmospheric Model Intercomparison Project (AMIP). DOI: 10.1034/j.1600-0870.1996.00001.x

Ming-cheng Yen - One of the best experts on this subject based on the ideXlab platform.

  • Annual Variation of Surface Pressure on a High East Asian Mountain and Its Surrounding Low Areas
    Journal of Climate, 1999
    Co-Authors: Tsing-chang Chen, Ming-cheng Yen
    Abstract:

    Abstract An inverse Annual Variation is observed between surface pressure on the highest mountain, which has an elevation of approximately 4000 m, and in the lowlands of Taiwan (a subtropical island in east Asia). This inverse Annual Variation in surface pressure of high and low elevation in low latitudes reflects, essentially, a vertical phase reversal of the tropical circulation, which is illustrated with the Annual Variation in the vertical structure of tropical geopotential height.

  • Annual Variation of the global precipitable water and its maintenance: observation and climate-simulation
    Tellus A: Dynamic Meteorology and Oceanography, 1996
    Co-Authors: Tsing-chang Chen, Ming-cheng Yen, James Pfaendtner, Y. C. Sud
    Abstract:

    The Annual Variation of the global-mean precipitable water 〈W〉and the associated hydrological cycle were analyzed with the upper-air data generated by the Global Data Assimilation System of the National Meteorological Center for 1981–1991 and the European Centre for Medium Range Weather Forecasts from 1983–1991. It was found that the Annual Variation of 〈W〉 coincides with that of the Northern Hemisphere precipitable water [W]NH. The hemispheric-mean ([ ]) water budget analysis shows that water vapor is transported from the winter to the summer hemisphere across the equator by the Hadley circulation, and that the Annual Variations in the water vapor sink [P – E] for both hemispheres also follow the same seasonal march. The amplitudes of the Annual Variations in these two hydrological processes are comparable in both hemispheres. Thus, the Annual Variations of [W]NH and [W]SH are the result of slight imbalances between the cross-equator water vapor transport and the water vapor sink, particularly in the spring and fall. The climatological hemispheric-mean water budgets reveal that the Southern Hemisphere is a water vapor source and the Northern Hemisphere is a water vapor sink. The cross-equator water vapor transport constitutes a major source acting to maintain [W]NH, and in turn 〈W〉. The hydrological mechanism maintaining the observed 〈W〉 Annual Variation is consistent with that obtained from the hydrological cycle in a 10-year (1979–1988) climate simulation done at the Goddard Laboratory for Atmospheres as part of their participation in the Atmospheric Model Intercomparison Project (AMIP). DOI: 10.1034/j.1600-0870.1996.00001.x