Sensitivity of Asian and African climate to variations in seasonal insolation, glacial ice cover, sea surface temperature, and Asian orography

The sensitivity of Asian and African climate to prescribed changes in specific high-latitude boundary conditions is examined using the GISS general circulation model (GCM) (8° × 10°). In agreement with previous GCM simulations, summer Asian monsoon winds and rainfall were considerably enhanced by the ∼8% increase in 11 kyr B.P. insolation; the African monsoon was less responsive to insolation forcing in this model. Increased high-latitude glacial ice cover strengthened winter Asian trade winds and imposed cooler and drier conditions over Arabia and northeastern Africa; summer monsoon winds and associated precipitation were diminished over parts of south Asia. Increased high-latitude ice cover alone had little effect on African climate. Cooler North Atlantic sea surface temperatures (SSTs) enhanced winter trade wind circulation over North Africa, promoted cooler and drier conditions, and reduced the summer monsoon circulation; southern Asian climate was relatively unaffected. Reducing Himalayan and Tibetan elevation to 500 m produced dramatic increases in winter Asian trade wind circulation; the summer monsoon circulation persisted but was weakened considerably. African climate was relatively insensitive to the reduced Asian orography. Many of the model results agree qualitatively with available paleoclimate data. These model results suggest that African and southern Asian climate respond to separate elements of high-latitude climate variability. Specifically, Arabian and northeastern African climate is most sensitive to changes in Fennoscandian ice elevation and albedo, whereas northwestern African climate is most sensitive to changes in the North Atlantic SST field.

[1]  J. Duplessy,et al.  Variations of the monsoon regime during the upper quaternary: Evidence from carbon isotopic record of organic matter in North Indian Ocean sediment cores , 1986 .

[2]  S. Clemens,et al.  Forcing mechanisms of the Indian Ocean monsoon , 1991, Nature.

[3]  J. D. Hays,et al.  Variations in the Earth ' s Orbit : Pacemaker of the Ice Ages Author ( s ) : , 2022 .

[4]  Alan C. Mix,et al.  Surface water response of the equatorial Atlantic Ocean to orbital forcing , 1989 .

[5]  A. Mcintyre,et al.  Ice-age thermal response and climatic role of the surface Atlantic Ocean, 40°N to 63°N , 1984 .

[6]  orographic Influence of the Tibetan Plateau on the Asiatic Winter Monsoon Circulation Part L Large-Scale Aspects 1 , 1981 .

[7]  E. Bard,et al.  Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U–Th ages from Barbados corals , 1990, Nature.

[8]  Maureen E. Raymo,et al.  Evolution of Atlantic―Pacific δ13C gradients over the last 2.5 m.y. , 1990 .

[9]  André Berger,et al.  Long-Term Variations of Caloric Insolation Resulting from the Earth's Orbital Elements , 1978, Quaternary Research.

[10]  J. Prospero.  Arid regions as sources of mineral aerosols in the marine atmosphere , 1981 .

[11]  John Z. Imbrie,et al.  Modeling the Climatic Response to Orbital Variations , 1980, Science.

[12]  W. Prell,et al.  Coherent response of Arabian Sea upwelling and pollen transport to late Quaternary monsoonal winds , 1986, Nature.

[13]  S. Manabe,et al.  The Effects of Mountains on the General Circulation of the Atmosphere as Identified by Numerical Experiments , 1974 .

[14]  J. Fontes,et al.  Water-level fluctuations of Lake Tanganyika in phase with oceanic changes during the last glaciation and deglaciation , 1989, Nature.

[15]  W. Prell,et al.  Late Cenozoic uplift in southern Asia and the American West: Rationale for general circulation modeling experiments , 1989 .

[16]  J. Overpeck,et al.  Climate change in the circum-North Atlantic region during the last deglaciation , 1989, Nature.

[17]  J. Duplessy,et al.  Late quaternary climatic changes in western tropical africa deduced from deep-sea sedimentation off the Niger delta , 1978 .

[18]  S. Clemens,et al.  Late Pleistocene variability of Arabian Sea summer monsoon winds and continental aridity: Eolian records from the lithogenic component of deep‐sea sediments , 1990 .

[19]  J. Kutzbach,et al.  Monsoon Climate of the Early Holocene: Climate Experiment with the Earth's Orbital Parameters for 9000 Years Ago , 1981, Science.

[20]  R. Ramesh,et al.  Oxygen isotope evidence for a stronger winter monsoon current during the last glaciation , 1990, Nature.

[21]  A. Lézine.  West African Paleoclimates during the Last Climatic Cycle Inferred from an Atlantic Deep-Sea Pollen Record , 1991, Quaternary Research.

[22]  S. Clemens,et al.  Late quaternary forcing of Indian Ocean summer-monsoon winds : a comparison of Fourier model and general circulation model results , 1991 .

[23]  D. Rind,et al.  Terrestrial Conditions at the Last Glacial Maximum and CLIMAP Sea-Surface Temperature Estimates: Are They Consistent? , 1985, Quaternary Research.

[24]  D. Rind.  The Dynamics of Warm and Cold Climates , 1986 .

[25]  Janice M. Lough,et al.  Tropical Atlantic Sea Surface Temperatures and Rainfall Variations in Subsaharan Africa , 1986 .

[26]  J. D. Hays,et al.  The Significance of Calcium Carbonate Oscillations in Eastern Equatorial Atlantic deep-Sea Sediments for the End of the Holocene Warm Interval , 1972, Quaternary Research.

[27]  D. Parkin,et al.  Trade Wind and Temperature Correlations down a Deep-sea Core off the Saharan Coast , 1973, Nature.

[28]  C. S. Ramage.  The Summer Atmospheric Circulation over the Arabian Sea , 1966 .

[29]  P. Biscaye,et al.  Distribution and origin of quartz in the sediments of the Indian Ocean , 1977 .

[30]  H. A. Mcclure.  Radiocarbon chronology of late Quaternary lakes in the Arabian Desert , 1976, Nature.

[31]  A. T. Grove,et al.  Global Maps of Lake-Level Fluctuations since 30,000 yr B.P. , 1979, Quaternary Research.

[32]  P. deMenocal,et al.  Evidence for a change in the periodicity of tropical climate cycles at 2.4 Myr from whole-core magnetic susceptibility measurements , 1989, Nature.

[33]  A. M. Swain,et al.  Holocene Variations of Monsoon Rainfall in Rajasthan , 1981, Quaternary Research.

[34]  W. Broecker,et al.  The impact of cold North Atlantic sea surface temperatures on climate: implications for the Younger Dryas cooling (11–10 k) , 1986 .

[35]  M. Sarnthein,et al.  Glacial and interglacial wind regimes over the eastern subtropical Atlantic and North-West Africa , 1981, Nature.

[36]  J. Kutzbach,et al.  Estimates of Holocene Precipitation for Rajasthan, India, Based on Pollen and Lake-Level Data , 1983, Quaternary Research.

[37]  A. Mcintyre,et al.  Nutricline variation in the equatorial Atlantic coincident with the Younger Dryas , 1990 .

[38]  P. Biscaye,et al.  Distributions and origins of clay minerals and quartz in surface sediments of the Arabian Sea , 1981 .

[39]  D. Rind,et al.  Increased ocean heat transports and warmer climate , 1991 .

[40]  Edward A. Boyle,et al.  North Atlantic thermohaline circulation during the past 20,000 years linked to high-latitude surface temperature , 1987, Nature.

[41]  D. Rind.  Components of the ice age circulation , 1987 .

[42]  M. Sarnthein,et al.  Climatic changes in the western Sahara: Aeolo-marine sediment record of the last 8 million years (Sites 657-661) , 1989 .

[43]  Jan Backman,et al.  Pleistocene evolution: Northern hemisphere ice sheets and North Atlantic Ocean , 1989 .

[44]  M. Rossignol-Strick.  African monsoons, an immediate climate response to orbital insolation , 1983, Nature.

[45]  J. Kutzbach,et al.  Sensitivity of climate to late Cenozoic uplift in southern Asia and the American west: Numerical experiments , 1989 .

[46]  J. Duplessy,et al.  Climatic conditions deduced from a 150-kyr oxygen isotope–pollen record from the Arabian Sea , 1982, Nature.

[47]  R. Jaenicke,et al.  Comprehensive study of physical and chemical properties of the surface aerosols in the Cape Verde Islands region , 1978 .

[48]  P. deMenocal,et al.  INFLUENCES OF HIGH- AND LOW-LATITUDE PROCESSES ON AFRICAN TERRESTRIAL CLIMATE:PLEISTOCENE EOLIAN RECORDS , 1993 .

[49]  P. Müller,et al.  Productivity, sedimentation rate, and sedimentary organic matter in the oceans—I. Organic carbon preservation , 1979 .

[50]  L. Druyan.  GCM studies of the African summer monsoon , 1987 .

[51]  S. Manabe,et al.  The Role of Mountains in the South Asian Monsoon Circulation , 1975 .

[52]  J. Kutzbach,et al.  Milankovitch forcing of fluctuations in the level of tropical lakes from 18 to 0 kyr BP , 1985, Nature.

[53]  J. Bloemendal,et al.  A Rock-Magnetic Record of Monsoonal Dust Deposition to the Arabian Sea: Evidence for a Shift in the Mode of Deposition at 2.4 Ma , 1991 .

[54]  Peter H. Stone,et al.  Efficient Three-Dimensional Global Models for Climate Studies: Models I and II , 1983 .

[55]  J. Kutzbach,et al.  Forcing of late Cenozoic northern hemisphere climate by plateau uplift in southern Asia and the American west , 1989 .

[56]  P. Lamb.  Case Studies of Tropical Atlantic Surface Circulation Patterns During Recent Sub-Saharan Weather Anomalies: 1967 and 1968 , 1978 .

[57]  R. Chester,et al.  The concentration of particulate aluminum and clay minerals in aerosols from the northern Arabian Sea , 1985 .

[58]  P. Biscaye,et al.  Clay mineralogy and sedimentation in the eastern Indian Ocean , 1973 .

[59]  J. Prospero,et al.  Dust Concentration in the Atmosphere of the Equatorial North Atlantic: Possible Relationship to the Sahelian Drought , 1977, Science.

[60]  E. I. Robson,et al.  Multifrequency observations of OV236 (1921–293) reveal an unusual spectrum , 1983, Nature.

[61]  G. P. Lohmann,et al.  Reconstructing past particle fluxes in the tropical Atlantic ocean , 1990 .

[62]  Elmar R. Reiter,et al.  The Atmospheric Heat Source over the Tibetan Plateau: May–August 1979 , 1985 .

[63]  L. Dupont,et al.  The Saharan–Sahelian boundary during the Brunhes chron , 1989 .

[64]  V. Ittekkot,et al.  Increased particle flux to the deep ocean related to monsoons , 1989, Nature.

[65]  Gurdip Singh,et al.  Stratigraphic and Radiocarbon Evidence for the Age and Development of Three Salt Lake Deposits in Rajasthan, India , 1972, Quaternary Research.

[66]  A. Mix,et al.  Eolian Evidence for Spatial Variability of Late Quaternary Climates in Tropical Africa , 1985, Quaternary Research.

[67]  Michael P. Bacon,et al.  Thorium 230 profiling in deep‐sea sediments: High‐resolution records of flux and dissolution of carbonate in the equatorial Atlantic during the last 24,000 years , 1990 .

[68]  E. Goldberg,et al.  The sediments of the northern Indian Ocean , 1970 .

[69]  H. Hooghiemstra,et al.  Isopollen maps for 18,000 years B.P. of the Atlantic offshore of northwest Africa: Evidence for paleowind circulation , 1987 .

[70]  J. Kutzbach,et al.  Monsoon variability over the past 150,000 years , 1987 .

[71]  L. Dupont,et al.  First palynological results from Site 658 at 21°N off Northwest Africa: Pollen as climate indicators. In Ruddiman, W., Sarnthein, M. et al. , 1989 .

[72]  J. Kutzbach,et al.  The Sensitivity of the African-Asian Monsoonal Climate to Orbital Parameter Changes for 9000 Years B.P. in a Low-Resolution General Circulation Model. , 1982 .

[73]  D. Short,et al.  Tropical climatic phase lags and Earth's precession cycle , 1986, Nature.