Influence of stratiform clouds on δD and δ18O of monsoon water vapour and rain at two tropical coastal stations

Lekshmy, P. R.; Midhun, M.; Ramesh, R.

doi:10.1016/j.jhydrol.2018.06.001

Cited by 27 publications

(13 citation statements)

References 47 publications

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“…However, the very significant relationship between the isotopic observations in water vapor and their expected values at equilibrium ( r 2 = 0.78, p < 0.01) indicates that equilibrium prevails when considering a longer time scale (here 2 weeks). This suggests that the isotopic equilibrium is a more robust assumption at the subseasonal scale than for individual rain events, as already pointed out in previous studies (Deshpande et al, 2010; Lekshmy et al, 2018) and that the simplifying hypothesis of the isotopic equilibrium between water vapor and tree source water, which is often made in tree ring studies, can be well founded.…”

Section: Discussionsupporting

confidence: 65%

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ¹⁸O_cellulose Estimate

et al. 2020

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Modeling work of the isotopic composition of tree ring cellulose (δ18Ocell) relies on the isotopic equilibrium assumption between atmospheric water vapor and tree source water, frequently assimilated to integrated precipitation. Here, we explore the veracity of this assumption based on observations collected during a field campaign in Río Negro province (Argentina) in February–March 2017. We examine how the observed isotopic composition of water vapor deviates from equilibrium with precipitation. This deviation, named isotopic disequilibrium (Δ18Ovap_eq), is low (between −2.0‰ and 4.1‰) and a significant relationship is observed between the isotopic composition of water vapor and its expected value at equilibrium. Negative Δ18Ovap_eq can be explained by evaporation of small raindrops (from 1% to 5% of initial droplet mass). Positive Δ18Ovap_eq can result from vegetation transpiration with transpired water accounting for 14% to 29% to ambient water vapor. The low Δ18Ovap_eq at the study site may be due to the high level of relative humidity (from 70% to 96%) favoring isotopic diffusive exchanges between the two water phases and thus promoting the isotopic equilibrium. We examine the impact of the isotopic equilibrium assumption on the calculation of δ18Ocell. A perfect agreement is shown between observed and calculated δ18Ocell provided that the isotopic composition of source water is significantly higher than the expected averaged isotopic composition of precipitation over the tree growing period.

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Section: Discussionsupporting

confidence: 65%

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ¹⁸O_cellulose Estimate

et al. 2020

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“…Daily observations showed deviations from the equilibrium fractionation factors (Fig. b), which could be attributable to the raindrops reevaporation below the clouds during their descent (Lekshmy et al, ; Li & Garzione, ). The raindrop reevaporation effect can be evaluated as the proportion of reevaporation required for the modelled values to match the observed values during the study period.…”

Section: Discussionmentioning

confidence: 99%

“…Each snowfall was packed into plastic bags sealed under room temperature until the snow was absolutely melted into water. Atmospheric water samples were collected with a portable vapour trap system at the SSBF during the premonsoon (April‐ mid June) and monsoon (late June‐September) seasons in 2014 (Lekshmy et al, ; Yu et al, ). The premonsoon and monsoon periods were defined according to the precipitation characteristics in China (Lü, Zhang, Tao, & Ju, ).…”

Section: Methodsmentioning

confidence: 99%

“…Recent studies have indicated that temperature effect on water vapour isotopes was found during premonsoon periods without amount effect (He & Richards, ), but amount effect changed the vapour δ 18 O during the monsoon periods (Yin et al, ). Moreover, reevaporation of raindrops and isotopic exchange of raindrops with ambient moisture also greatly affect the variations of water vapour isotopes and thus increase the deviation from precipitation across seasons (Lekshmy, Midhun, & Ramesh, ; Rahul et al, ). Knowledge gaps still exist on the variations of water vapour isotopes across seasons, and the interaction between rain and vapour from Qinghai Lake, located in the Northeast Tibetan Plateau.…”

Section: Introductionmentioning

confidence: 99%

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Stable isotopes of atmospheric water vapour and precipitation in the northeast Qinghai‐Tibetan Plateau

Zhang³

et al. 2019

Hydrological Processes

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Stable water isotopes (δ18O and δ2H) are an important source signature for understanding the hydrological cycle and altered climate regimes. However, the mechanisms underlying atmospheric water vapour isotopes in the northeast Qinghai‐Tibetan Plateau of central Asia remain poorly understood. This study initially investigated water vapour isotopic composition and its controls during the premonsoon and monsoon seasons. Isotopic compositions of water vapour and precipitation exhibited high variability across seasons, with the most negative average δ18O values of precipitation and the most positive δ18O values of water vapour found during the premonsoon periods. Temperature effect was significant during the premonsoon period but not the monsoon period. Both a higher slope and intercept of the local meteoric water line were found during the monsoon period as compared with in the premonsoon period, suggesting that raindrops have been experienced a greater kinetic fractionation process such as reevaporation below the cloud during the premonsoon periods. The δ2H and δ18O signatures in atmospheric water vapour tended to be depleted with the occurrence of precipitation events especially during the monsoon period and probably as a result of rainout processes. The monthly average contribution of evaporation from the lake to local precipitation was 35.2%. High d‐excess values of water vapour were influenced by the high proportion of local moisture mixing, as indicated by the gradually increasing relative humidity along westerly and Asian monsoon trajectories. The daily observation (observed ε) showed deviations from the equilibrium fractionation factors (calculated ε), implying that raindrops experienced substantial evaporative enrichment during their descent. The average fraction of raindrops reevaporation was estimated to be 16.4± 12.9%. These findings provide useful insights for understanding the interaction between water vapour and precipitation, moisture sources, and help in reconstructing the paleoclimate in the alpine regions.

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“…A large number of precipitation isotope data, mostly on a monthly timescale, is available with GNIP. Various investigators have used the data in understanding a variety of atmospheric and hydrological processes [1][2][3][4][5][6][7][8]. Specific statistical techniques have also been proposed to interpret the data [9,10].…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of the Precipitation Isotope Data with Reference to the Indian Subcontinent

Chakraborty¹,

Birmal²,

Burman³

et al. 2021

Hydrology

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The isotopic analysis of precipitation provides useful information on a variety of hydrological and atmospheric processes. The dynamical characteristics of precipitation isotopes have been well investigated, but a systematic study of their statistical behavior seems to be lacking. We have performed the statistical analysis, basically the distribution characteristics of precipitation isotopes visa -vis rainfall data for specific regions. The probability distribution functions of precipitation isotopes have been calculated from local to global scales. It has been observed that the isotopic values, in general, followed a pattern that is similar to the normal distribution, though the rainfall distribution patterns are very different. Under certain circumstances, the isotopic distribution patterns closely resemble the normal distribution, implying a well-constrained moisture source contributing to precipitation. The distribution patterns of oxygen and hydrogen isotopes on continental and global scales show similar behavior. It was observed that the distribution patterns of primary isotopic variables (δ 18 O and δD) are not very sensitive to the outliers. On the contrary, the secondary parameter, d-excess, is very sensitive to outliers, which offers an effective means to quality control of the precipitation isotopic values.

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Influence of stratiform clouds on δD and δ18O of monsoon water vapour and rain at two tropical coastal stations

Cited by 27 publications

References 47 publications

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ¹⁸O_cellulose Estimate

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ¹⁸O_cellulose Estimate

Stable isotopes of atmospheric water vapour and precipitation in the northeast Qinghai‐Tibetan Plateau

Statistical Analysis of the Precipitation Isotope Data with Reference to the Indian Subcontinent

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Influence of stratiform clouds on δD and δ18O of monsoon water vapour and rain at two tropical coastal stations

Cited by 27 publications

References 47 publications

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ18Ocellulose Estimate

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ18Ocellulose Estimate

Stable isotopes of atmospheric water vapour and precipitation in the northeast Qinghai‐Tibetan Plateau

Statistical Analysis of the Precipitation Isotope Data with Reference to the Indian Subcontinent

Contact Info

Product

Resources

About

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ¹⁸O_cellulose Estimate

Isotopic Equilibrium Between Precipitation and Water Vapor in Northern Patagonia and Its Consequences on δ¹⁸O_cellulose Estimate