Investigating soil moisture-climate interactions in a changing climate: A review

The International Atomic Energy Agency (IAEA), in cooperation with the World Meteorological Organization (WMO), has been conducting a world-wide survey of hydrogen (H/'H) and oxygen (O/O) isotope composition of monthly precipitation since 1961 At present, 72 IAEA/WMO network stations are in operation Another 82 stations belonging to national organizations continue to send their results to the IAEA for publication The paper focuses on basic features of spatial and temporal distribution of deuterium and O in global precipitation, as derived from the IAEA/WMO isotope database The internal structure and basic characteristics of this database are discussed in some detail The existing phenomenological relationships between observed stable isotope composition of precipitation and various climate-related parameters such as local surface air temperature and amount of precipitation are reviewed and critically assessed Attempts are presented towards revealing interannual fluctuations in the accumulated isotope records and relating them to changes of precipitation amount and the surface air temperature over the past 30 years

Isotopic Patterns in Modern Global Precipitation

A continuous deuterium profile along the 160,000-year Vostok ice core (Antarctica) is interpreted in terms of atmospheric temperature changes. This climatic record is the awaited terrestrial complement of the deep-sea records supporting the existence of a relation between the Pleistocene climate and orbital forcing.

Vostok ice core: a continuous isotope temperature record over the last climatic cycle (160,000 years)

Proxy data reflecting the oxygen isotope composition of meteoric precipitation (δ18Oppt) are widely used in reconstructions of continental paleoclimate and paleohydrology. However, actual geographic variation in modern water compositions is difficult to estimate from often sparse data. A first step toward understanding the geologic pattern of change in δ18Oppt is to describe the modern distribution in terms of principal geographic parameters. To this end, we empirically model relationships between 18O in modern precipitation and latitude and altitude. We then identify geographic areas where large-scale vapor transport patterns give rise to significant deviations from model δ18Oppt compositions based on latitude and altitude. Model value and residual grids are combined to derive a high-resolution global map of δ18Oppt that can serve as a spatial reference against which proxy data for paleoprecipitation can be compared. Reiteration of the procedure outlined here, for paleo-δ18Oppt data, may illuminate past changes in the climatic and physiographic parameters controlling the distribution of δ18O regimes.

Spatial distribution of δ18O in meteoric precipitation

The classical Rayleigh model assuming isotopic equilibrium fails to explain the deuterium and oxygen 18 contents of polar snow. This model leads to too high temperature-isotope gradients (both for δD and δ18O), to too low δD - δ18O slopes, and consequently to an excessively large range of deuterium excess values (d = δD - 8δ18O). We present a new model that takes into account the existence of an isotopic kinetic effect at snow formation as a result of the fact that vapor deposition occurs in an environment supersaturated over ice. This kinetic effect is thoroughly discussed from a microphysical point of view and tested against experimental data and field observations. This new formulation reconciles predicted and observed values both for the temperature-isotope and δD - δD18O relationships for reasonable values of supersaturation over ice.

Deuterium and oxygen 18 in precipitation: Modeling of the isotopic effects during snow formation

H218O and HDO are important climatic tracers largely used to reconstruct continental palaeoclimates. The only thorough way to compare isotopic distributions in precipitation for modern and palaeoconditions is to simulate isotope cycles using atmospheric general circulation models. H218O and HDO cycles incorporated into our atmospheric general circulation model show good agreement between observed and predicted values for modern conditions.

A general circulation model of water isotope cycles in the atmosphere

Simulation of the HDO and H2 18O Cycles in an Atmospheric General Circulation Model (Abstract)

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Robert Sadourny

Papers

A general circulation model of water isotope cycles in the atmosphere

Simulation of the HDO and H2 18O Cycles in an Atmospheric General Circulation Model (Abstract)

Erratum: A general circulation model of water isotope cycles in the atmosphere