A one‐dimensional simulation of the water vapor isotope HDO in the tropical stratosphere

Ridal, Martin; Jönsson, Andreas; Werner, Martin; Murtagh, Donal

doi:10.1029/2000jd000268

Cited by 15 publications

(22 citation statements)

References 31 publications

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“…The rate constants used for the new reactions are to a majority the same as for their respective unsubstituted reactions. It is shown however, by Ridal et al [2001] that the reaction rates have little effect on the resulting isotopic ratio of water vapor.…”

Section: One‐dimensional Modelmentioning

confidence: 99%

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Isotopic ratios of water vapor and methane in the stratosphere: Comparison between ATMOS measurements and a one‐dimensional model

Ridal

2002

J. Geophys. Res.

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[1] A one-dimensional model simulating the transport and chemistry of methane and water vapor including their isotopic ratios in the tropical stratosphere is compared to measurements by the Atmospheric Trace Molecule Spectroscopy experiment (ATMOS) instrument. The model and measurements show good agreement in the isotopic ratio profiles. The dD depletion for water vapor is À600% to À500% at the tropopause with a small increase up to $10 hPa. Above this altitude the modeled isotopic ratio shows a strong increase due to methane oxidation. The measured profiles are rather noisy above 10 hPa but give an indication of a stronger increase in the isotopic ratio than modeled. If the isotopic ratio of water vapor is allowed to vary at the tropopause simulating an annual cycle in the input values, a wave pattern that is transported upwards arises on the vertical profile. This is a similar effect as the ''tape recorder'' for water vapor. A wave pattern can also be detected in the tropical dD profiles from ATMOS. The methane isotopic ratio shows behavior similar to that of water vapor but without the wave pattern. The increase in methane dD above 10 hPa is very strong. The measured profiles are again rather noisy above this altitude, but measurements from inside the polar vortex show that the methane isotopic ratio in the upper stratosphere is very high. The dD values are in the range of +300% to +500% at altitudes as low as 40 hPa ($25 km) in the polar vortex.

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Section: One‐dimensional Modelmentioning

confidence: 99%

“…The isotopic ratio is presented using the standard δ D notation with reference ratios taken from the Standard Mean Ocean Water (SMOW) [ Ridal et al , 2001; Craig , 1961].…”

Section: Introductionmentioning

confidence: 99%

Isotopic ratios of water vapor and methane in the stratosphere: Comparison between ATMOS measurements and a one‐dimensional model

Ridal

2002

J. Geophys. Res.

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“…Measurements and modeling of less abundant isotopes of water vapor and their ratio to the main isotope in the troposphere have been used for some time in the study of the paleoclimate [e.g., Jouzel et al , 1987]. For studies of dynamical processes in the stratosphere, for example the exchange between the stratosphere and the troposphere or the age of air, the isotopic ratio of water vapor is a new rather unexplored method [ Ridal et al , 2001; Moyer et al , 1996]. The water vapor isotopic ratio with respect to deuterium is expected to change with altitude inside the stratosphere, or rather the time spent in the stratosphere.…”

Section: Introductionmentioning

confidence: 99%

A two‐dimensional simulation of the isotopic composition of water vapor and methane in the upper atmosphere

Ridal

Siskind

2002

J.‐Geophys.‐Res.

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[1] A chemical oxidation scheme where CH 3 D produces HDO has been incorporated into a two-dimensional model to simulate the transport and isotopic composition chemistry of stratospheric methane and water. The model results show that deuterium ratios in water and methane are good tracers of stratospheric dynamics. Comparisons with measurements by the ATMOS instrument suggest that the modeled methane isotopic ratio is too low in the upper stratosphere and mesosphere. The very low amount of CH 4 and CH 3 D in the middle to upper stratosphere makes the isotopic ratio for methane more sensitive to model uncertainties than the isotopic ratio of water vapor. One reason for the too low isotopic ratio values may be that the reaction rates in the oxidation of CH 3 D are slower than assumed. The isotopic ratio for methane was very sensitive to changes in the rate constants for the reactions of CH 3 D with OH, O( 1 D) and Cl, while the water vapor isotopic ratio only shows small changes.

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“…Kaye (1990) first studied δ 18 O(H 2 O) in the middle atmosphere and suggested a significant increase in δ 18 O(H 2 O) with altitude due to 18 O-rich excess water from CH 4 oxidation. Ridal et al (2001) and Ridal (2002) focused on δD(H 2 O) in the stratosphere. They found a strong vertical increase of δD(H 2 O), also due to CH 4 oxidation which is additionally modulated by the seasonally varying H 2 O input from the troposphere (the "tape recorder effect").…”

Section: Introductionmentioning

confidence: 99%

Modelling the budget of middle atmospheric water vapour isotopes

Zahn¹,

Franz

Bechtel

et al. 2006

Atmos. Chem. Phys.

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Abstract.A one-dimensional chemistry model is applied to study the stable hydrogen (D) and stable oxygen isotope ( 17 O, 18 O) composition of water vapour in stratosphere and mesosphere. In the troposphere, this isotope composition is determined by "physical" fractionation effects, that are phase changes (e.g. during cloud formation), diffusion processes (e.g. during evaporation from the ocean), and mixing of air masses. Due to these processes water vapour entering the stratosphere first shows isotope depletions in D/H relative to ocean water, which are ∼5 times of those in 18 In the stratosphere the known mass-independent fractionation (MIF) signal in O 3 is in a first step transferred to the NO x family and only in a second step to HO x and H 2 O. In contrast to CO 2 , O( 1 D) only plays a minor role in this MIF transfer. The major uncertainty in our calculation arises from poorly quantified isotope exchange reaction rate coefficients and kinetic isotope fractionation factors.

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A one‐dimensional simulation of the water vapor isotope HDO in the tropical stratosphere

Cited by 15 publications

References 31 publications

Isotopic ratios of water vapor and methane in the stratosphere: Comparison between ATMOS measurements and a one‐dimensional model

Isotopic ratios of water vapor and methane in the stratosphere: Comparison between ATMOS measurements and a one‐dimensional model

A two‐dimensional simulation of the isotopic composition of water vapor and methane in the upper atmosphere

Modelling the budget of middle atmospheric water vapour isotopes

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