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  • 1
    Electronic Resource
    Electronic Resource
    Sensitivity of simulated Asian and African summer monsoons to orbitally induced variations in insolation 126, 115 and 6 kBP (1996)
    Springer
    Climate dynamics 12 (1996), S. 589-603 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We have conducted four numerical experiments with an atmospheric general circulation model (AGCM) to investigate the sensitivity of Asian and African monsoons to small changes (−5 to +12%), with respect to present-day, in incoming solar radiation at the top of the atmosphere. We show that, during the mid-Holocene (6 kBP where kBP means thousands of years before present-day) and the last interglacial (126 kBP), the Northern Hemisphere seasonal contrast was increased, with warmer summers and colder winters. At the time of glacial inception (115 kBP) however, summers were cooler and winters milder. As a consequence, Asia and tropical North Africa experienced stronger (weaker) summer monsoons 6 and 126 kBP (115 kBP), in agreement with previous numerical studies. This present study shows that summer warming/cooling of Eurasia and North Africa induced a shift of the main low-level convergence cell along a northwest/southeast transect. When land was warmer (during the summer months 6 and 126 kBP), the monsoon winds converged further inland bringing more moisture into northern India, western China and the southern Sahara. The southern tips of India, Indochina and southeastern China, as well as equatorial North Africa became drier. When land was cooler (during the summer 115 kBP), the main convergence zone was located over the west Pacific and the wet (dry) areas were those that were dry (wet) 6 and 126 kBP. The location and intensity of the simulated precipitation maxima were therefore very sensitive to changes in insolation. However the total amount of monsoon rain in Asia as well as in Africa remained remarkably stable through the time periods studied. These simulated migrations of convective activities were accompanied by changes in the nature of precipitation events: increased monsoon rains in these experiments were always associated with more high precipitation events (〉 5 mm day −1), and fewer light showers (≤1 mm day−). Rainy days with rates between 1 and 5 mm day−1 were almost unchanged.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216268
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Sensitivity of simulated Asian and African summer monsoons to orbitally induced variations in insolation 126, 115 and 6 kBP (1996)
    Springer
    Climate dynamics 12 (1996), S. 589-603 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. We have conducted four numerical experiments with an atmospheric general circulation model (AGCM) to investigate the sensitivity of Asian and African monsoons to small changes (–5 to +12%), with respect to present-day, in incoming solar radiation at the top of the atmosphere. We show that, during the mid-Holocene (6 kBP where kBP means thousands of years before present-day) and the last interglacial (126 kBP), the Northern Hemisphere seasonal contrast was increased, with warmer summers and colder winters. At the time of glacial inception (115 kBP) however, summers were cooler and winters milder. As a consequence, Asia and tropical North Africa experienced stronger (weaker) summer monsoons 6 and 126 kBP (115 kBP), in agreement with previous numerical studies. This present study shows that summer warming/cooling of Eurasia and North Africa induced a shift of the main low-level convergence cell along a northwest/southeast transect. When land was warmer (during the summer months 6 and 126 kBP), the monsoon winds converged further inland bringing more moisture into northern India, western China and the southern Sahara. The southern tips of India, Indochina and southeastern China, as well as equatorial North Africa became drier. When land was cooler (during the summer 115 kBP), the main convergence zone was located over the west Pacific and the wet (dry) areas were those that were dry (wet) 6 and 126 kBP. The location and intensity of the simulated precipitation maxima were therefore very sensitive to changes in insolation. However the total amount of monsoon rain in Asia as well as in Africa remained remarkably stable through the time periods studied. These simulated migrations of convective activities were accompanied by changes in the nature of precipitation events: increased monsoon rains in these experiments were always associated with more high precipitation events (〉5 mm day–1), and fewer light showers (≤1 mm day–1). Rainy days with rates between 1 and 5 mm day–1 were almost unchanged.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216268
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    On the ability of the LODYC GCM to simulate the thermocline depth in the equatorial Atlantic (1994)
    Springer
    Climate dynamics 9 (1994), S. 221-234 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. Using a multivariate model testing procedure that distinguishes between model inadequacies and data uncertainties, we investigate the ability of the LODYC GCM to simulate the evolution of the 20° C isotherm depth during the 1982–1984 FOCAL/SEQUAL experiment in the equatorial Atlantic. Two different versions of the model are considered: the “Ri” version which has a Richardson number dependent parameterization of vertical mixing and the new “TKE” version which uses a local estimation of the turbulent kinetic energy to parameterize vertical mixing. Some effects of the forcing uncertainties are considered by forcing the TKE version with three equally plausible wind stress fields whose differences are consistent with the measurement and sampling errors, and the drag coefficient indeterminacy. The resulting uncertainties in the model response are substantial and can be as large as the differences between simulations with the two GCM versions, which stresses the need to take the forcing uncertainties into account. Although only one Ri run is available, it is shown that the “TKE” parameterization significantly improves the representation of the equatorial upwelling and the simulation of the depth of the thermocline in the eastern Atlantic. However, there remain significant differences with the observations which cannot be explained by the forcing uncertainties that were considered. The two model versions perform better in the equatorial wave guide than in the 12° N–12° S domain, and they are better distinguished over large domains than along sections, which shows that a global multivariate view point must be used in model-reality comparisons. Finally, a comparison with a linear multimode model emphasizes the need for greater model complexity to properly simulate the equatorial upwelling and the thermocline variability in the tropical Atlantic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050021
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    On the ability of the LODYC GCM to simulate the thermocline depth in the equatorial Atlantic (1994)
    Springer
    Climate dynamics 9 (1994), S. 221-234 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Using a multivariate model testing procedure that distinguishes between model inadequacies and data uncertainties, we investigate the ability of the LODYC GCM to simulate the evolution of the 20°C isotherm depth during the 1982–1984 FOCAL/SEQUAL experiment in the equatorial Atlantic. Two different versions of the model are considered: the “Ri” version which has a Richardson number dependent parameterization of vertical mixing and the new “TKE” version which uses a local estimation of the turbulent kinetic energy to parameterize vertical mixing. Some effects of the forcing uncertainties are considered by forcing the TKE version with three equally plausible wind stress fields whose differences are consistent with the measurement and sampling errors, and the drag coefficient indeterminacy. The resulting uncertainties in the model response are substantial and can be as large as the differences between simulations with the two GCM versions, which stresses the need to take the forcing uncertainties into account. Although only one Ri run is available, it is shown that the “TKE” parameterization significantly improves the representation of the equatorial upwelling and the simulation of the depth of the thermocline in the eastern Atlantic. However, there remain significant differences with the observations which cannot be explained by the forcing uncertainties that were considered. The two model versions perform better in the equatorial wave guide than in the 12°N-12°S domain, and they are better distinguished over large domains than along sections, which shows that a global multivariate view point must be used in model-reality comparisons. Finally, a comparison with a linear multimode model emphasizes the need for greater model complexity to properly simulate the equatorial upwelling and the thermocline variability in the tropical Atlantic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208254
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
  • 5
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    Understanding ENSO diversity (2015)
    American Meteorological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 96 (2015): 921–938, doi:10.1175/BAMS-D-13-00117.1.
    Description: El Niño–Southern Oscillation (ENSO) is a naturally occurring mode of tropical Pacific variability, with global impacts on society and natural ecosystems. While it has long been known that El Niño events display a diverse range of amplitudes, triggers, spatial patterns, and life cycles, the realization that ENSO’s impacts can be highly sensitive to this event-to-event diversity is driving a renewed interest in the subject. This paper surveys our current state of knowledge of ENSO diversity, identifies key gaps in understanding, and outlines some promising future research directions.
    Description: AC acknowledges support from the National Science Foundation for this study.
    Description: 2015-12-01
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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    PAPER (OA)
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