scholarly journals The isotopic composition of water vapour and precipitation in Ivittuut, southern Greenland

2014 ◽  
Vol 14 (9) ◽  
pp. 4419-4439 ◽  
Author(s):  
J.-L. Bonne ◽  
V. Masson-Delmotte ◽  
O. Cattani ◽  
M. Delmotte ◽  
C. Risi ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Isotopic Composition ◽  
Water Vapour ◽  
General Circulation ◽  
Winter Season ◽  
First Record ◽  
Back Trajectory ◽  
Deuterium Excess ◽  
Local Surface ◽  
Moisture Source

Abstract. Since September 2011, a wavelength-scanned cavity ring-down spectroscopy analyser has been remotely operated in Ivittuut, southern Greenland, providing the first record of surface water vapour isotopic composition based on continuous measurements in South Greenland and the first record including the winter season in Greenland. The comparison of vapour data with measurements of precipitation isotopic composition suggest an equilibrium between surface vapour and precipitation. δ18O and deuterium excess are generally anti-correlated and show important seasonal variations, with respective amplitudes of ~10 and ~20‰, as well as large synoptic variations. The data depict small summer diurnal variations. At the seasonal scale, δ18O has a minimum in November–December and a maximum in June–July, while deuterium excess has a minimum in May–June and a maximum in November. The approach of low-pressure systems towards South Greenland leads to δ18O increase (typically +5‰) and deuterium excess decrease (typically −15‰). Seasonal and synoptic variations coincide with shifts in the moisture sources, estimated using a quantitative moisture source diagnostic based on a Lagrangian back-trajectory model. The atmospheric general circulation model LMDZiso correctly captures the seasonal and synoptic variability of δ18O, but does not capture the observed magnitude of deuterium excess variability. Covariations of water vapour isotopic composition with local and moisture source meteorological parameters have been evaluated. δ18O is strongly correlated with the logarithm of local surface humidity, consistent with Rayleigh distillation processes, and with local surface air temperature, associated with a slope of ~0.4‰ °C−1. Deuterium excess correlates with local surface relative humidity as well as surface relative humidity from the dominant moisture source area located in the North Atlantic, south of Greenland and Iceland.

scholarly journals The isotopic composition of water vapour and precipitation in Ivittuut, Southern Greenland

2013 ◽  
Vol 13 (11) ◽  
pp. 30521-30574 ◽  
Author(s):  
J.-L. Bonne ◽  
V. Masson-Delmotte ◽  
O. Cattani ◽  
M. Delmotte ◽  
C. Risi ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Isotopic Composition ◽  
Water Vapour ◽  
Seasonal Variations ◽  
General Circulation ◽  
Deuterium Excess ◽  
Local Surface ◽  
Long Distance ◽  
Atlantic Sector ◽  
Moisture Sources

Abstract. Since September 2011, a Wavelength-Scanned Cavity Ringdown Spectroscopy analyzer has been remotely operated in Ivittuut, southern Greenland, providing the first continuous record of surface water vapour isotopic composition (δ18O, δD) in South Greenland and the first record including the winter season in Greenland. This record depicts small summer diurnal variations. Measurements of precipitation isotopic composition suggest equilibrium between surface vapour and precipitation. The vapour data show large synoptic and seasonal variations corresponding to shifts in moisture sources estimated using a quantitative moisture source diagnostic. The arrival of low pressure systems towards south Greenland leads to δ18O enrichment (+5‰) and deuterium excess depletion (−15‰), coupled with moisture sources shifts. Monthly δ18O is minimum in November–December and maximum in June–July, with a seasonal amplitude of ~10‰. The strong correlation between δ18O and the logarithm of local surface humidity is consistent with Rayleigh distillation processes. The relationship with local surface air temperature is associated with a slope of ~0.4‰ °C−1. During the summer 2012 heat waves, the observations display a divergence between δ18O and local climate variables, probably due to the isotopic depletion associated with long distance transport from subtropical moisture sources. Monthly deuterium excess is minimum in May–June and maximum in November, with a seasonal amplitude of 20‰. It is anti-correlated with δ18O, and correlated with local surface relative humidity (at the station) as well as surface relative humidity in a North Atlantic sector, south of Greenland and Iceland. While synoptic and seasonal variations are well represented by the Atmospheric General Circulation Model LMDZiso for Ivittuut δ18O, the model does not capture the magnitude of these variations for deuterium excess.

scholarly journals Deuterium excess as a proxy for continental moisture recycling and plant transpiration

2013 ◽  
Vol 13 (11) ◽  
pp. 29721-29784 ◽  
Author(s):  
F. Aemisegger ◽  
S. Pfahl ◽  
H. Sodemann ◽  
I. Lehner ◽  
S. I. Seneviratne ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Monitoring Site ◽  
Deuterium Excess ◽  
Plant Transpiration ◽  
Surface Evaporation ◽  
Moisture Source ◽  
Moisture Recycling ◽  
Continental Scale ◽  
Measurement Site

Abstract. Studying the evaporation process and its link to the atmospheric circulation is central for a better understanding of the feedbacks between the surface water components and the atmosphere. Stable water isotopes are ideal tools to investigate surface evaporation as they are naturally available tracers of water phase changes in the atmosphere. The strength of isotope fractionation processes depends on environmental conditions such as relative humidity and temperature. In this study, we use five months of deuterium excess (d) measurements at the hourly to daily timescale from a cavity ring-down laser spectrometer to characterise the evaporation source of low-level continental water vapour at the long-term hydrometeorological monitoring site Rietholzbach in northeastern Switzerland. To reconstruct the phase change history of the air masses in which we measure the d signature and to diagnose its area of surface evaporation we apply an established Lagrangian moisture source diagnostic. With the help of a correlation analysis we investigate the strength of the relation between d measurements and the moisture source conditions. Temporal episodes with a duration of a few days of strong anticorrelation between d and relative humidity as well as temperature are identified. The role of plant transpiration, the large-scale advection of remotely evaporated moisture, the local boundary layer dynamics at the measurement site and recent precipitation at the site of evaporation are discussed as reasons for the existence of these modes of strong anticorrelation between d and moisture source conditions. The relation between d in atmospheric water vapour at the measurement site and the relative humidity conditions at the location of evaporation exhibits distinct characteristics for land surface evaporation and ocean evaporation. We show that the importance of continental moisture recycling and the contribution of plant transpiration to the continental evaporation flux can be deduced from the d-relative humidity relation at the seasonal timescale as well as for individual events. The slope of the relation between d and the diagnosed moisture source relative humidity provides a novel framework to estimate the transpiration fraction of land evapotranspiration at the local to continental scale. Over the whole analysis period (August to December 2011) a transpiration fraction of the evapotranspiration flux over the continental part of the moisture source region of 63% is found albeit with a large event-to-event variability (0% to 99%) for continental Europe. During days of strong local moisture recycling a higher overall transpiration fraction of 82% (varying between 65% and 94%) is found. Such Lagrangian estimates of the transpiration part of continental evaporation could potentially be useful for the verification of model estimates of this important land-atmosphere coupling parameter.

scholarly journals Simulation of the isotopic composition of stratospheric water vapour – Part 1: Description and evaluation of the EMAC model

2015 ◽  
Vol 15 (10) ◽  
pp. 5537-5555 ◽  
Author(s):  
R. Eichinger ◽  
P. Jöckel ◽  
S. Brinkop ◽  
M. Werner ◽  
S. Lossow
Keyword(s):  
Isotopic Composition ◽  
Water Vapour ◽  
General Circulation ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Isotope Ratios ◽  
Physical Fractionation ◽  
Water Isotopologues ◽  
Stratospheric Water Vapour

Abstract. This modelling study aims at an improved understanding of the processes that determine the water vapour budget in the stratosphere by means of the investigation of water isotope ratios. An additional (and separate from the actual) hydrological cycle has been introduced into the chemistry–climate model EMAC, including the water isotopologues HDO and H218O and their physical fractionation processes. Additionally an explicit computation of the contribution of methane oxidation to H2O and HDO has been incorporated. The model expansions allow detailed analyses of water vapour and its isotope ratio with respect to deuterium throughout the stratosphere and in the transition region to the troposphere. In order to assure the correct representation of the water isotopologues in the model's hydrological cycle, the expanded system has been evaluated in several steps. The physical fractionation effects have been evaluated by comparison of the simulated isotopic composition of precipitation with measurements from a ground-based network (GNIP) and with the results from the isotopologue-enabled general circulation model ECHAM5-wiso. The model's representation of the chemical HDO precursor CH3D in the stratosphere has been confirmed by a comparison with chemical transport models (1-D, CHEM2D) and measurements from radiosonde flights. Finally, the simulated stratospheric HDO and the isotopic composition of water vapour have been evaluated, with respect to retrievals from three different satellite instruments (MIPAS, ACE-FTS, SMR). Discrepancies in stratospheric water vapour isotope ratios between two of the three satellite retrievals can now partly be explained.

scholarly journals The Isotopic Composition of Present-Day Antarctic Snow in a Lagrangian Atmospheric Simulation*

2007 ◽  
Vol 20 (4) ◽  
pp. 739-756 ◽  
Author(s):  
M. M. Helsen ◽  
R. S. W. Van de Wal ◽  
M. R. Van den Broeke
Keyword(s):  
Isotopic Composition ◽  
General Circulation ◽  
Isotopic Fractionation ◽  
General Circulation Models ◽  
Deuterium Excess ◽  
West Antarctica ◽  
Temperature Relation ◽  
Weather Forecasts ◽  
Spatial Differences ◽  
Antarctic Snow

Abstract The isotopic composition of present-day Antarctic snow is simulated for the period September 1980–August 2002 using a Rayleigh-type isotope distillation model in combination with backward trajectory calculations with 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data as meteorological input. Observed spatial isotopic gradients are correctly reproduced, especially in West Antarctica and in the coastal areas. However, isotopic depletion of snow on the East Antarctic plateau is underestimated, a problem that is also observed in general circulation models equipped with isotope tracers. The spatial isotope–temperature relation varies strongly, which indicates that this widely used relation is not applicable to all sites and temporal scales. Spatial differences in the seasonal amplitude are identified, with maximum values in the Antarctic interior and hardly any seasonal isotope signature in Marie Byrd Land, West Antarctica. The modeled signature of deuterium excess remains largely preserved during the last phase of transport, though the simulated relation of deuterium excess with δ18O suggests that parameterizations of kinetic isotopic fractionation can be improved.

scholarly journals Modelling the isotopic composition of snow using backward trajectories: a particular precipitation event in Dronning Maud Land, Antarctica

2004 ◽  
Vol 39 ◽  
pp. 293-299 ◽  
Author(s):  
Michiel M. Helsen ◽  
Roderik S. W. Van De Wal ◽  
Michiel R. Van Den Broeke ◽  
Erik R. Th. Kerstel ◽  
Valérie Masson-Delmotte ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Water Vapour ◽  
General Circulation ◽  
General Circulation Models ◽  
Precipitation Event ◽  
Backward Trajectories ◽  
Specific Accumulation ◽  
Transport Path ◽  
History Of ◽  
Dronning Maud Land

AbstractWe consider a specific accumulation event that occurred in January 2002 in western Dronning Maud Land, Antarctica. Snow samples were obtained a few days after accumulation. We combine meteorological analyses and isotopic modelling to describe the isotopic composition of moisture during transport. Backward trajectories were calculated, based on European Centre for Medium-Range Weather Forecasts operational archive data so that the history of the air parcels transporting water vapour to the accumulation site could be reconstructed. This trajectory study showed that the air masses were not (super)saturated along most of the transport path, which is in contrast with assumptions in Lagrangian fractionation models and probably true for most precipitation events in Antarctica. The modelled fractionation along the trajectories was too limited to explain the measured isotopic content of the snow. It is shown that the observed isotopic composition of precipitation resulted from fractionation of initially more depleted water. This lower initial isotopic composition of water vapour might result from atmospheric mixing with more depleted air along the trajectory or from earlier condensation cycles, not captured by the trajectories. This is in accordance with isotope fields resulting from general circulation models, indicating a gradient in isotopic composition from the Equator to Antarctica.

scholarly journals Response of water vapour D-excess to land-atmosphere interactions in a semi-arid environment

2016 ◽  
Author(s):  
Stephen D. Parkes ◽  
Matthew F. McCabe ◽  
Alan D. Griffiths ◽  
Lixin Wang ◽  
Scott Chambers ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Relative Humidity ◽  
Water Vapour ◽  
Regional Scale ◽  
Measurement Techniques ◽  
Spatial And Temporal Variability ◽  
Moisture Source ◽  
Moisture Recycling ◽  
Nocturnal Inversion ◽  
Semi Arid

Abstract. The stable isotopic composition of water vapour provides information about moisture sources and processes that is difficult to obtain with traditional measurement techniques. Recently, it has been proposed that the D-excess (dv = δ2H − 8 × δ18O) of water vapour can provide a diagnostic tracer of continental moisture recycling. However, D-excess exhibits a diurnal cycle that has been observed across a variety of ecosystems and may be influenced by a range of processes beyond regional scale moisture recycling, including local evaporation (ET) fluxes. There is a lack of measurements of D-excess in evaporation (ET) fluxes, which has made it difficult to assess how ET fluxes modify the D-excess in water vapour (dv). With this in mind, we employed a chamber based approach to directly measure D-excess in ET (dET) fluxes. We show that ET fluxes imposed a negative forcing on the ambient vapour and could not explain the higher daytime dv values. The low dET observed here was sourced from a soil water pool that had undergone an extended drying period, leading to low D-excess of the soil moisture. A strong correlation between daytime dv and locally measured relative humidity was consistent with an oceanic moisture source, suggesting that remote hydrological processes were the major contributor to daytime dv variability. During the early evening, ET fluxes into a shallow nocturnal inversion layer caused a lowering of the dv values near the surface. In addition, transient mixing of vapour with a higher D-excess from above the nocturnal inversion modified these values, causing large within night variability. These results indicate dET can generally be expected to show large spatial and temporal variability and to depend on the soil moisture state. For long periods between rain events, common in semi-arid environments, ET would be expected to impose negative forcing on the surface dv. The variability of D-excess in ET fluxes therefore needs to be considered when using dv to study moisture recycling and during extended dry periods may act as a tracer of the relative humidity of the oceanic moisture source.

scholarly journals Simulation of the isotopic composition of stratospheric water vapour – Part 1: Description and evaluation of the EMAC model

2014 ◽  
Vol 14 (17) ◽  
pp. 23807-23846 ◽  
Author(s):  
R. Eichinger ◽  
P. Jöckel ◽  
S. Brinkop ◽  
M. Werner ◽  
S. Lossow
Keyword(s):  
Isotopic Composition ◽  
Water Vapour ◽  
General Circulation ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Isotope Ratios ◽  
Physical Fractionation ◽  
Water Isotopologues ◽  
Stratospheric Water Vapour

Abstract. This modelling study aims on an improved understanding of the processes, that determine the water vapour budget in the stratosphere by means of the investigation of water isotope ratios. At first, a separate hydrological cycle has been introduced into the chemistry-climate model EMAC, including the water isotopologues HDO and H218O and their physical fractionation processes. Additionally an explicit computation of the contribution of methane oxidation to HDO has been incorporated. The model expansions allow detailed analyses of water vapour and its isotope ratio with respect to deuterium throughout the stratosphere and in the transition region to the troposphere. In order to assure the correct representation of the water isotopologues in the model's hydrological cycle, the expanded system has been evaluated in several steps. The physical fractionation effects have been evaluated by comparison of the simulated isotopic composition of precipitation with measurements from a ground-based network (GNIP) and with the results from the isotopologue-enabled general circulation model ECHAM5-wiso. The model's representation of the chemical HDO precursor CH3D in the stratosphere has been confirmed by a comparison with chemical transport models (CHEM1D, CHEM2D) and measurements from radiosonde flights. Finally, the simulated stratospheric HDO and the isotopic composition of water vapour have been evaluated, with respect to retrievals from three different satellite instruments (MIPAS, ACE-FTS, SMR). Discrepancies in stratospheric water vapour isotope ratios between two of the three satellite retrievals can now partly be explained.

scholarly journals Three-year monitoring of stable isotopes of precipitation at Concordia Station, East Antarctica

2016 ◽  
Author(s):  
Barbara Stenni ◽  
Claudio Scarchilli ◽  
Valerie Masson-Delmotte ◽  
Elisabeth Schlosser ◽  
Virginia Ciardini ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Isotopic Composition ◽  
Air Temperature ◽  
General Circulation ◽  
Daily Precipitation ◽  
Circulation Model ◽  
Ice Cores ◽  
Condensation Temperature ◽  
Deuterium Excess ◽  
Medium Range Weather Forecast

Abstract. Past temperature reconstructions from Antarctic ice cores require a good quantification and understanding of the relationship between snow isotopic composition and 2&thninsp;m air or inversion (condensation) temperature. Here, we focus on the French-Italian Concordia Station, central East Antarctic plateau, where the European Project for Ice Coring in Antarctica (EPICA) Dome C ice cores were drilled. We provide a multi-year record of daily precipitation types identified from crystal morphologies, daily precipitation amounts, and isotopic composition. Our sampling period (2008–2010) encompasses a warmer year (2009, +1.6 °C with respect to 2&thninsp;m air temperature period average), with larger total precipitation and snowfall amounts (14 %, 76 % above average, respectively), and a colder and drier year (2010, −1.4 °C, 4 % below average, respectively) with larger diamond dust amounts (49 % above average). Relationships between local meteorological data and precipitation isotopic composition are investigated at daily, monthly and inter-annual scale, and for the different types of precipitation. Water stable isotopes are more closely related to 2 m air temperature than to inversion temperature at all time scales (e.g. R2 = 0.63 and 0.44, respectively for daily values). The slope of the temporal relationship between daily d18O and 2 m air temperature is approximately two times smaller (0.49 ‰/°C) than the average Antarctic spatial (0.8 ‰/°C) relationship initially used for the interpretation of EPICA Dome C records. In accordance to results from precipitation monitoring at Vostok and Dome F, deuterium excess is anti-correlated with δ18O at daily and monthly scales, reaching maximum values in winter. Hoar frost precipitation samples have a specific fingerprint with more depleted d18O (about 5 ‰ below average) and higher deuterium excess (about 8 ‰ above average) values than other precipitation types. These datasets provide a basis for comparison with shallow ice core records, to investigate post-deposition effects. A preliminary comparison between observations and precipitation from the European Centre for Medium-Range Weather Forecast (ECMWF) re-analysis and the simulated water stable isotopes from the Laboratoire de Météorologie Dynamique Zoom atmospheric general circulation model (LMDZiso), shows that models do correctly capture the amount of precipitation as well as more than 50 % of the variance of the observed δ18O, driven by large scale weather patterns. Despite a warm bias and an underestimation of the variance in water stable isotopes, LMDZiso correctly captures these relationships between δ18O, 2 m air temperature and deuterium excess. Our dataset is therefore available for further in depth model evaluation at the synoptic scale.

scholarly journals Continuous measurements of atmospheric water vapour isotopes in western Siberia (Kourovka)

2014 ◽  
Vol 7 (6) ◽  
pp. 1763-1776 ◽  
Author(s):  
V. Bastrikov ◽  
H. C. Steen-Larsen ◽  
V. Masson-Delmotte ◽  
K. Gribanov ◽  
O. Cattani ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Water Vapour ◽  
Land Surface ◽  
Western Siberia ◽  
First Record ◽  
Atmospheric Water ◽  
Diurnal Variability ◽  
Total Uncertainty ◽  
Atmospheric Water Vapour ◽  
Isotopic Measurements

Abstract. The isotopic composition of atmospheric water vapour at the land surface has been continuously monitored at the Kourovka astronomical observatory in western Siberia (57.037° N, 59.547° E; 300 m a.s.l.) since April 2012. These measurements provide the first record of δD, δ18O and d-excess in this region. Air was sampled at 8 m height within a forest clearing. Measurements were made with a wavelength-scanned cavity ring-down spectroscopy analyzer (Picarro L2130-i). Specific improvements of the measurement system and calibration protocol have been made to ensure reliable measurements at low humidity during winter. The isotopic measurements conducted till August 2013 exhibit a clear seasonal cycle with maximum δD and δ18O values in summer and minimum values in winter. In addition, considerable synoptic timescale variability of isotopic composition was observed with typical variations of 50–100‰ for δD, 10–15‰ for δ18O and 2–8‰ for d-excess. The strong correlations between δD and local meteorological parameters (logarithm of humidity and temperature) are explored, with a lack of dependency in summer that points to the importance of continental recycling and local evapotranspiration. The overall correlation between δD and temperature is associated with a slope of 3‰ °C−1. Large d-excess diurnal variability was observed during summer with up to 30‰ decrease during the night and the minima manifested shortly after sunrise. Two dominant diurnal cycle patterns for d-excess differing by the magnitude of the d-excess decrease (21‰ and 7‰) and associated patterns for meteorological observations have been determined. The total uncertainty of the isotopic measurements was quantified as 1.4–11.2‰ for δD, 0.23–1.84‰ for δ18O and 2.3–18.5‰ for d-excess depending on the humidity.

scholarly journals Precipitation regime and stable isotopes at Dome Fuji, East Antarctica

2016 ◽  
Vol 16 (11) ◽  
pp. 6883-6900 ◽  
Author(s):  
Anna Dittmann ◽  
Elisabeth Schlosser ◽  
Valérie Masson-Delmotte ◽  
Jordan G. Powers ◽  
Kevin W. Manning ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Annual Cycle ◽  
Source Region ◽  
Precipitation Event ◽  
Deuterium Excess ◽  
Antarctic Plateau ◽  
Moisture Source ◽  
The Antarctic ◽  
The Impact ◽  
Precipitation Events

Abstract. A unique set of 1-year precipitation and stable water isotope measurements from the Japanese Antarctic station, Dome Fuji, has been used to study the impact of the synoptic situation and the precipitation origin on the isotopic composition of precipitation on the Antarctic Plateau. The Antarctic Mesoscale Prediction System (AMPS) archive data are used to analyse the synoptic situations that cause precipitation. These situations are investigated and divided into five categories. The most common weather situation during a precipitation event is an upper-level ridge that extends onto the Antarctic Plateau and causes strong northerly advection from the ocean. Most precipitation events are associated with an increase in temperature and wind speed, and a local maximum of δ18O. During the measurement period, 21 synoptically caused precipitation events caused 60 % of the total annual precipitation, whereas the remaining 40 % were predominantly attributed to diamond dust. By combining the synoptic analyses with 5-day back-trajectories, the moisture source regions for precipitation events were estimated. An average source region around a latitude of 55° S was found. The atmospheric conditions in the source region were used as initial conditions for running a Rayleigh-type isotopic model in order to reproduce the measured isotopic composition of fresh snow and to investigate the influence of the precipitation source region on the isotope ratios. The model represents the measured annual cycle of δ18O and the second-order isotopic parameter deuterium excess reasonably well, but yields on average too little fractionation along the transport/cooling path. While simulations with an isotopic general circulation model (GCM) (ECHAM5-wiso) for Dome Fuji are on average closer to the observations, this model cannot reproduce the annual cycle of deuterium excess. In the event-based analysis, no evidence of a correlation of the measured deuterium excess with the latitude of the moisture source region or the corresponding conditions was identified. Contrary to the assumption used for decades in ice core studies, a more northerly moisture source does not necessarily mean a larger temperature difference between source area and deposition site, thus a more depleted precipitation in heavy isotopes with a higher deuterium excess.

Sign in / Sign up

Export Citation Format

Share Document