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Linkage between Seasonal insolation Gradient in the Tropical Northern Hemisphere and the Sea Surface Salinity of the Equatorial Indian Ocean during the Last Glacial Period

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Acta Geologica Sinica(English Edition) 2012年第5期86卷 1265-1275页

作者： Saraswat RAJEEV Nigam RAJIV Mackensen ANDREAS Weldeab SYEE Micropaleontology Laboratory National Institute of OceanographyGoaIndia Alfred Wegner Institute for Polar and Marine Research BremerhavenGermany Department of Earth Science University of CaliforniaSanta BarbaraUSA

Paired stable oxygen isotope and Mg/Ca analyses in calcite tests of the mixed-layer-dwelling planktic foraminifer Globigerinoides ruber has been used to reconstruct equatorial Indian Oceanδ18O of seawater （δ 18Osw ） over the last ~137 thousand years. On the basis of ice-volume-correctedδ18Osw （δ18Osw-ivc ）, relative changes in sea surface salinity （SSS） have been estimated. The SSS estimates suggest three episodes of higher SSS （131-113 thousand years before present （kyr BP）, 62-58 kyr BP, and 30-24 kyr BP） within the last glacial period as compared with the present. SSS comparison between interglacial episodes reveals that the surface seawater over the core site was significantly saltier during the penultimate interglacial than the Holocene. We suggest that the evolution of a seasonal insolation gradient between the Indian monsoon areas and the equator over the investigated time interval was instrumental in shaping the strength of the Indian winter and summer monsoons that left their imprints on the equatorial Indian Ocean SSS via freshwater input and wind-induced mixing. The study shows that the insolation difference between northern latitudes and the equator during winter affects monsoon strength in the Indian region, especially during cold intervals.

关键词： oxygen isotope Mg/Ca Globigerinoides ruber salinity insolation Indian Ocean

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Climate variability recorded by n-alkanes of paleolake sediment in Qaidam Basin on the northeast Tibetan Plateau in late MIS3

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Science China Earth Sciences 2010年第6期53卷 863-870页

作者： PU Yang ZHANG HuCai LEI GuoLiang CHANG FengQin YANG MingSheng ZHANG WenXiang LEI YanBin YANG LunQing PANG YouZhi State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China Graduate University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Boyang Lake MOESchool of Environmental and Chemical EngineeringNanchang UniversityNanchang 330031China

Here we combine n-alkanes preserved in a shell bar section from Qarhan paleolake, Qaidam Basin with the other sedimentary proxies to elucidate the lake evolution process during the period 39.7 to 17.5 14C ka BP (calibrated age ranges from 43.5 to 22.4 cal. ka BP). In different stages, the n-alkane homologues exhibited different distribution modes indicative of variations in the surrounding vegetation and the hydrologic condition of the lake. The n-alkanes proxies (CPIh, ACLh, Paq) have the same trends as the summer solar insolation variation, implying that the summer insolation is the most important climatic factor driving the environmental changes and also indirectly controls lake evolution on the Tibetan Plateau. CPIh and ACLh as well as the total pollen concentration appear to show a trend comparable with methane concentration record from the GRIP ice core that reflected the Dansgaard-Oeschger events. This demonstrates that the paleoclimate variations in Qarhan area generally agree with global climate change and show rapid oscillations in late MIS3. These findings provide the latest molecular fossil evidence from paleolake sediments to confirm that lake evolution on Tibetan Plateau in late MIS3 was closely associated with enhanced summer insolation.

关键词： paleolake sediment molecular fossil n-alkane paleoclimate paleoenvironment solar insolation

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Implications for soil environment from uranium isotopes of stalagmites

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Chinese Science Bulletin 2002年第19期47卷 1653-1658页

作者： KUANG Runyuan WANG Yongjin ZHANG Xianghua CHENG Hai College of Geographical Science Nanjing Normal UniversityNanjing 210097China Department of Geology and Geophysics Minnesota UniversityMN55455USA

By analyzing U and Th isotopic compositions of 41 samples in two stalagmites from Hulu Cave, Nanjing, we first discovered that variations of 238U and δ234U0 along the stalagmite growth-sequence (covering a period from 75 to 18 kaBP) are in high similarity to summer insolation curve at 33°N and δ18O-based climate record of the studied stalagmites. The concentration of 238U is mainly controlled by content of organic matter in the soil above the cave. This mechanism can be used to explain our result that 238U curve of stalagmites is in phase with fluctuation of the δ18O record of the same stalagmites and summer insolation at cave locality. However, 238U concentration curve vs. age is, in amplitude, inconsistent with the climatic curves, possibly due to complex processes of soil-water-rock interaction. δ234U0 indicates pedogenic intensity of soil profile above the cave and sensitively reflects alternations of pedogenesis and aeolian accumulation processes of Xiashu loess in Nanjing. Consequently,

关键词： U concentration δ234U0 organic matter of soil insolation palaeoclimatic proxy.

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Late Twentieth-Century Warming and Variations in Cloud Cover

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Atmospheric and Climate Sciences 2014年第4期4卷 727-742页

作者： John McLean Department of Physics College of Science Technology and Engineering James Cook University Townsville Australia

From 1950 to 1987 a strong relationship existed between the El Nino-Southern Oscillation (ENSO) and HadCRUT4 global average temperature anomaly, interrupted occasionally by volcanic erup-tions. After 1987 the relationship diverged, with temperature anomaly increasing more than ex-pected, but was re-established after 1997 at an offset of ~0.48°C higher. The period of increased warming from 1987 to 1997 loosely coincided with the divergence of the global average tempera-ture anomalies over land, which are derived from observation station recordings, and the global average anomalies in sea surface temperatures. Land-based temperatures averaged 0.04°C below sea temperatures for the period 1950 to 1987 but after 1997 averaged 0.41°C above sea tempera-tures. The increase in the global average temperature anomaly and the divergence of land and sea surface temperatures also coincided with two significant changes in global average cloud cover. Total cloud cover decreased during the period from 1987 to 1997 and, for most of the remainder of the period from 1984 to 2009, decreases in low-level cloud were accompanied by increases in middle and upper level cloud. These changes can be found in both global average cloud cover and in each of the six 30°C-latitude bands. The impact of these changes in cloud cover can account for the variations in HadCRUT4 global average temperature anomalies and the divergence between land and sea temperatures.

关键词： Climate Change Temperature Shift insolation ENSO ISCCP HadCRUT4

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New Long-Term Climate Oscillations

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Natural Science 2021年第8期13卷 354-371页

作者： Joseph J. Smulsky Institute of Earth’s Cryosphere Tyum. SC of SB RAS Federal Research Center Tyumen Russia

The astronomical theory of climate change is based on the solution of differential equations describing Earth’s orbital and rotational motions. The equations are used to calculate the change in insolation over the Earth’s surface. As a result of the author’s solution of the orbital problem, the periods and amplitudes of Earth-orbit variations and their evolution have been refined. Unlike previous studies, the equations of Earth’s rotational motion are solved completely. The Earth’s rotational axis precesses relative to a direction different from the direction of the orbit’s axial precession, and oscillates with periods of half a month, half a year and 18.6 years. Also, its oscillations occur with irregular periods of several tens of thousands of years and more. All these motions lead to oscillations of the obliquity in the range of 14.7° to 32.1°, which prove to be 7 - 8 times larger than obtained by a previous theory. In the same proportion, the Earth’s insolation oscillations increase in amplitude, with insolation extremes occurring in other epochs than those in the previous theory. The amplitudes and the onset times of the extremes correlate with known paleoclimate changes. Thirteen insolation periods of paleoclimate variation over an interval of 200 thousand years are identified. From the insolation evolution calculated over a time interval of 1 million years, 6 climate gradations from very cold to very warm are identified.

关键词： Earth’s Orbit and Axis Evolution insolation Climate Change Ice Ages

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