Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region
About: This article is published in Geophysical Research Letters.The article was published on 2021-06-16. It has received 24 citations till now. The article focuses on the topics: East Asian Monsoon & Monsoon trough.
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TL;DR: In this paper, the effects of global seawater and local temperature changes can be quantitatively removed, yielding a record of local seawater δ18O, which responds primarily to dilution by local precipitation and runoff.
Abstract: Speleothem CaCO3 δ18O is a commonly employed paleomonsoon proxy. However, inferring local rainfall amount from speleothem δ18O can be complicated due to changing source water δ18O, temperature effects, and rainout over the moisture transport path. These complications are addressed using δ18O of planktonic foraminiferal CaCO3, offshore from the Yangtze River Valley (YRV). The advantage is that the effects of global seawater δ18O and local temperature changes can be quantitatively removed, yielding a record of local seawater δ18O, a proxy that responds primarily to dilution by local precipitation and runoff. Whereas YRV speleothem δ18O is dominated by precession-band (23 ky) cyclicity, local seawater δ18O is dominated by eccentricity (100 ky) and obliquity (41 ky) cycles, with almost no precession-scale variance. These results, consistent with records outside the YRV, suggest that East Asian monsoon rainfall is more sensitive to greenhouse gas and high-latitude ice sheet forcing than to direct insolation forcing.
52 citations
TL;DR: In this paper , the authors presented a well-dated, high-resolution (~70 years), ice-free-season temperature (from March to October, TM-O) record over the past 19 ka from a small alpine lake on the southeastern Tibetan Plateau based on brGDGT proxy.
30 citations
TL;DR: Zhang et al. as mentioned in this paper examined the distribution pattern of n-alkanes in the aquatic plants within Lake Lugu (a deep alpine lake on the southeastern margin of the Tibetan Plateau, southwest China), and terrestrial plants and topsoils in the catchment, to unravel the origin of sedimentary nalkanes and further investigate the spatial distribution of surface sediments in this lake.
7 citations
TL;DR: In this paper , the authors compared 20 Holocene Lacustrine authigenic carbonate δ18O records from lakes distributed across the Tibetan Plateau and concluded that the long-term variations of the lacustrine records were dominated by the moisture sources.
5 citations
TL;DR: In this paper , the authors present a continuous compound-specific hydrogen isotope record of sedimentary leaf waxes covering the past 18 ka (ka = 1000 yr) from Ngamring Co, located in the upper-middle Yarlung Tsangpo range, a typical monsoonal region, with the aim of documenting hydroclimatic changes since the last deglaciation.
4 citations
References
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TL;DR: In this paper, the isotopic fractionation of water in simple condensation-evaporation processes is considered quantitatively on the basis of the fractionation factors given in section 1.2.
Abstract: In chapter 2 the isotopic fractionation of water in some simple condensation-evaporation processes are considered quantitatively on the basis of the fractionation factors given in section 1.2. The condensation temperature is an important parameter, which has got some glaciological applications. The temperature effect (the δ's decreasing with temperature) together with varying evaporation and exchange appear in the “amount effect” as high δ's in sparse rain. The relative deuterium-oxygen-18 fractionation is not quite simple. If the relative deviations from the standard water (S.M.O.W.) are called δ D and δ 18 , the best linear approximation is δ D = 8 δ 18 . Chapter 3 gives some qualitative considerations on non-equilibrium (fast) processes. Kinetic effects have heavy bearings upon the effective fractionation factors. Such effects have only been demonstrated clearly in evaporation processes, but may also influence condensation processes. The quantity d = δ D −8 δ 18 is used as an index for non-equilibrium conditions. The stable isotope data from the world wide I.A.E.A.-W.M.O. precipitation survey are discussed in chapter 4. The unweighted mean annual composition of rain at tropical island stations fits the line δ D = 4.6 δ 18 indicating a first stage equilibrium condensation from vapour evaporated in a non-equilibrium process. Regional characteristics appear in the weighted means. The Northern hemisphere continental stations, except African and Near East, fit the line δ D = 8.0 δ 18 + 10 as far as the weighted means are concerned (δ D = 8.1 δ 18 + 11 for the unweighted) corresponding to an equilibrium Rayleigh condensation from vapour, evaporated in a non-equilibrium process from S.M.O.W. The departure from equilibrium vapour seems even higher in the rest of the investigated part of the world. At most stations the δ D and varies linearily with δ 18 with a slope close to 8, only at two stations higher than 8, at several lower than 8 (mainly connected with relatively dry climates). Considerable variations in the isotopic composition of monthly precipitation occur at most stations. At low latitudes the amount effect accounts for the variations, whereas seasonal variation at high latitudes is ascribed to the temperature effect. Tokyo is an example of a mid latitude station influenced by both effects. Some possible hydrological applications are outlined in chapter 5. DOI: 10.1111/j.2153-3490.1964.tb00181.x
7,081 citations
Additional excerpts
...In the ISM region, some studies use the “amount effect” to interpret reconstructed changes in δ18Oc records based on modern observations, with lower δ18Oc values indicating more local or regional rainfall amount, and vice versa (Dansgaard, 1964; Cai et al., 2012; G. Liu, Li, et al., 2020)....
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TL;DR: In this paper, the authors present a detailed stable isotope record for the full length of the Greenland Ice-core Project Summit ice core, extending over the past 250 kyr according to a calculated timescale, and find that climate instability was not confined to the last glaciation, but appears also have been marked during the last interglacial (as explored more fully in a companion paper), and during the previous Saale-Holstein glacial cycle.
Abstract: RECENT results1,2 from two ice cores drilled in central Greenland have revealed large, abrupt climate changes of at least regional extent during the late stages of the last glaciation, suggesting that climate in the North Atlantic region is able to reorganize itself rapidly, perhaps even within a few decades. Here we present a detailed stable-isotope record for the full length of the Greenland Ice-core Project Summit ice core, extending over the past 250 kyr according to a calculated timescale. We find that climate instability was not confined to the last glaciation, but appears also to have been marked during the last interglacial (as explored more fully in a companion paper3) and during the previous Saale–Holstein glacial cycle. This is in contrast with the extreme stability of the Holocene, suggesting that recent climate stability may be the exception rather than the rule. The last interglacial seems to have lasted longer than is implied by the deep-sea SPECMAP record4, in agreement with other land-based observations5,6. We suggest that climate instability in the early part of the last interglacial may have delayed the melting of the Saalean ice sheets in America and Eurasia, perhaps accounting for this discrepancy.
4,367 citations
TL;DR: The record links North Atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer East Asian Monsoon originates and generally agrees with the timing of temperature changes from the Greenland Ice Sheet Project Two (GISP2).
Abstract: Oxygen isotope records of five stalagmites from Hulu Cave near Nanjing bear a remarkable resemblance to oxygen isotope records from Greenland ice cores, suggesting that East Asian Monsoon intensity changed in concert with Greenland temperature between 11,000 and 75,000 years before the present (yr. B.P.). Between 11,000 and 30,000 yr. B.P., the timing of changes in the monsoon, as established with 230Th dates, generally agrees with the timing of temperature changes from the Greenland Ice Sheet Project Two (GISP2) core, which supports GISP2's chronology in this interval. Our record links North Atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer East Asian Monsoon originates.
2,759 citations
TL;DR: Enzymic studies, radiolabeling, and electron microscopy will be needed to reveal the mode of biogenesis of the wax constituents and their site of formation and subsequent pathway through the cuticle to the leaf surface.
Abstract: The external surface of the higher plants comprises a cuticular layer covered by a waxy deposit. This deposit is believed to play a major part in such phenomena as the water balance of plants and the behavior of agricultural sprays. The wax contains a wide range of organic compounds. These complex mixtures are amenable to modern microchromatographic and microspectrometric analytical procedures. The few surveys which have been made of the species distribution of certain classes of constituents indicate that such distribution may be of limited taxonomic value; however, the wax composition of a species may differ for different parts of the same plant and may vary with season, locale, and the age of the plant. This fascinating subject, in which the disciplines of botany, biochemistry, chemistry, and physics overlap and interact, is still in a very active state. Much remains to be learned about the composition and fine structure of the wax deposits, and, for this, experimental study of wax crystallization and permeation through artificial membranes will be required. Enzymic studies, radiolabeling, and electron microscopy will be needed to reveal the mode of biogenesis of the wax constituents and their site of formation and subsequent pathway through the cuticle to the leaf surface.
2,381 citations
"Paleoclimate Significance of Recons..." refers background in this paper
...Longchain n-alkanes (e.g., C27, C29, C31) are present in epicuticular leaf waxes mainly from terrestrial higher plants (Eglinton & Hamilton, 1967), which use ambient soil water and thus rainfall for lipid biosynthesis (Sachse et al., 2012)....
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...…of Reconstructed Rainfall Isotopes The dominance of long-chain n-alkanes (C29 and C31) in our modern terrestrial plants and soils agrees with the previously recognized major source of terrestrial vascular plants for long-chain n-alkanes (Cranwell et al., 1987; Eglinton & Hamilton, 1967)....
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TL;DR: A global observational study of atmospheric conditions associated with tropical disturbance and storm development is presented in this article, which primarily uses upper air observations which have become available over the tropical oceans in the last decade.
Abstract: A global observational study of atmospheric conditions associated with tropical disturbance and storm development is presented. This study primarily uses upper air observations which have become available over the tropical oceans in the last decade. Climatological values of vertical stability, low level wind, tropospheric vertical wind shear and other parameters relative to the location and seasons of tropical disturbance and storm development are discussed. Individual storm data are also presented in summary form for over 300 development cases (with over 1,500 individual observation times) for four tropical storm genesis areas. Results show that most tropical disturbances and storms form in regions equatorward of 20° lat. on the poleward side of doldrum Equatorial Troughs where the tropospheric vertical shear of horizontal wind (i.e., baroclinicity) is a minimum or zero. Storm development occurring on the poleward side of 20° lat. in the Northwest Atlantic and North-west Pacific takes place unde...
1,776 citations