Precise and accurate measurements of the stable isotope composition from precipitation, land ice, runoff, and oceans provide critical information on Earth's water cycle. The analysis, post-processing, and calibration of raw analytical signals from laser spectrometers during sample analysis involves a number of critical procedures to counteract instrumental drift, inter-sample memory effects, and the quantification of total uncertainty. We present a new software tool for the post-processing and calibration named FLIIMP (FARLAB Liquid Water Isotope Measurement Processor).
View Article and Find Full Text PDFOcean isotopic evaporation models, such as the Craig-Gordon model, rely on the description of nonequilibrium fractionation factors that are, in general, poorly constrained. To date, only a few gradient-diffusion type measurements have been performed in ocean settings to test the validity of the commonly used parametrization of nonequilibrium isotopic fractionation during ocean evaporation. In this work, we present 6 months of water vapor isotopic observations collected from a meteorological tower located in the northwest Atlantic Ocean (Bermuda) with the objective of estimating nonequilibrium fractionation factors (, ‰) for ocean evaporation and their wind speed dependency.
View Article and Find Full Text PDFThe tropical West Pacific hosts the warmest part of the surface ocean and has a considerable impact on the global climate system. Reconstructions of past temperature in this region can elucidate climate connections between the tropics and poles and the sensitivity of tropical temperature to greenhouse forcing. However, existing data are equivocal and reliable information from terrestrial archives is particularly sparse.
View Article and Find Full Text PDFThe mid-latitude westerly winds of the Southern Hemisphere play a central role in the global climate system via Southern Ocean upwelling, carbon exchange with the deep ocean, Agulhas leakage (transport of Indian Ocean waters into the Atlantic) and possibly Antarctic ice-sheet stability. Meridional shifts of the Southern Hemisphere westerly winds have been hypothesized to occur in parallel with the well-documented shifts of the intertropical convergence zone in response to Dansgaard-Oeschger (DO) events- abrupt North Atlantic climate change events of the last ice age. Shifting moisture pathways to West Antarctica are consistent with this view but may represent a Pacific teleconnection pattern forced from the tropics.
View Article and Find Full Text PDFAtmospheric processes play an important role in the supply of the trace element selenium (Se) as well as other essential trace elements to terrestrial environments, mainly via wet deposition. Here we investigate whether the marine biosphere can be identified as a source of Se and of other trace elements in precipitation samples. We used artificial neural network (ANN) modeling and other statistical methods to analyze relationships between a high-resolution atmospheric deposition chemistry time series (March 2007-January 2009) from Plynlimon (UK) and exposure of air masses to marine chlorophyll a and to other source proxies.
View Article and Find Full Text PDF