Microphysical controls on the isotopic composition of wintertime orographic precipitation

Moore, M. H.; Blossey, Peter N.; Muhlbauer, Andreas; Kuang, Zhiming

doi:10.1002/2015jd023763

Cited by 32 publications

(34 citation statements)

References 70 publications

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“…These changes in δ 18 O P with mountain height and temperature are also governed by the microphysical processes through which precipitation is formed. For instance, lower δ 18 O P with increased altitude may reflect not only decreasing temperature but also the variable contributions and distinct isotopic signatures of riming of cloud liquid and vapor deposition onto snow (e.g., Aggarwal et al, ; Moore et al, ). In the case of the extreme high and low δ 18 O P events, each precipitation sample represents a snow event, with mean snowfall amounts of 36.9 and 43.4 mm for the high and low δ 18 O P events, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Journal of Geophysical Research: Atmospheres of cloud liquid and vapor deposition onto snow (e.g., Aggarwal et al, 2016;Moore et al, 2016). In the case of the extreme high and low δ 18 O P events, each precipitation sample represents a snow event, with mean snowfall amounts of 36.9 and 43.4 mm for the high and low δ 18 O P events, respectively.…”

Section: 1029/2018jd030050mentioning

confidence: 99%

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Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ¹⁸O/δ²H in South‐Central Alaska

2019

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Measurements of oxygen and hydrogen stable isotopes in precipitation (δ18OP and δ2HP) provide a valuable tool for understanding modern hydrological processes and the empirical foundation for interpreting paleoisotope archives. However, long‐term data sets of modern δ18OP and δ2HP in southern Alaska are entirely absent, thus limiting our insight and application of regionally defined climate‐isotope relationships in this proxy‐rich region. We present and utilize a 13‐year‐long record of event‐based δ18OP and δ2HP data from Anchorage, Alaska (2005–2018, n = 332), to determine the mechanisms controlling precipitation isotopes. Local surface air temperature explains ~30% of variability in the δ18OP data with a temperature‐δ18O slope of 0.31 ‰/°C, indicating that δ18OP archives may not be suitable paleo‐thermometers in this region. Instead, back‐trajectory modeling reveals how winter δ18OP/δ2HP reflects synoptic and mesoscale processes in atmospheric circulation that drive changes in the passage of air masses with different moisture sources, transport, and rainout histories. Specifically, meridional systems—with either northerly flow from the Arctic or southerly flow from the Gulf of Alaska—have relatively low δ18OP/δ2HP due to progressive cooling and removal of precipitation as it condenses with altitude over Alaska's southern mountain ranges. To the contrary, zonally derived moisture from either the North Pacific and/or Bering Sea retains relatively high δ18OP/δ2HP values. These new data contribute a better understanding of the modern Alaska water isotope cycle and provide an empirical basis for interpreting paleoisotope archives in context of regional atmospheric circulation.

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Section: Resultsmentioning

confidence: 99%

Section: 1029/2018jd030050mentioning

confidence: 99%

Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ¹⁸O/δ²H in South‐Central Alaska

2019

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“…Better diagnostics are needed for the many processes impacting isotopes in vapor related to circulation (e.g., impacts of residence time, Aggarwal et al, ; divergence, Bailey et al, ; Lee et al, ; precipitation efficiency, Bailey et al, ; cloud physics, Moore et al, ; and updraft strength on the isotopic signal Bolot et al, ), and we have yet to fully address the impact of horizontal transport, potentially using water tracer/tagging experiments. Further, recent modeling work has challenged the relationship between global convective mass flux M and the strength of the Walker circulation, which is formally defined by SLP gradients in the tropical Pacific (Sandeep et al, ).…”

Section: Discussion: Detecting Changes In the Walker Circulationmentioning

confidence: 99%

Tracking the Strength of the Walker Circulation With Stable Isotopes in Water Vapor

et al. 2018

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General circulation models (GCMs) predict that the global hydrological cycle will change in response to anthropogenic warming. However, these predictions remain uncertain, in particular, for precipitation (Intergovernmental Panel on Climate Change, 2013, https://doi.org/10.1017/CBO9781107415324.004). Held and Soden (2006, https://doi.org/10.1175/JCLI3990.1) suggest that as lower tropospheric water vapor concentration increases in a warming climate, the atmospheric circulation and convective mass fluxes will weaken. Unfortunately, this process is difficult to constrain, as convective mass fluxes are poorly observed and incompletely simulated in GCMs. Here we demonstrate that stable hydrogen isotope ratios in tropical atmospheric water vapor can trace changes in temperature, atmospheric circulation, and convective mass flux in a warming world. We evaluate changes in temperature, the distribution of water vapor, vertical velocity (ω), advection, and water isotopes in vapor (δDV). Using water isotope‐enabled GCM experiments for modern versus high‐CO2 atmospheres, we identify spatial patterns of circulation change over the tropical Pacific. We find that slowing circulation in the tropical Pacific moistens the lower troposphere and weakens convective mass flux, both of which impact the δD of water vapor in the midtroposphere. Our findings constitute a critical demonstration of how water isotope ratios in the tropical Pacific respond to changes in radiative forcing and atmospheric warming. Moreover, as changes in δDV can be observed by satellites, our results develop new metrics for the detection of global warming impacts to the hydrological cycle and, specifically, the strength of the Walker circulation.

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“…Insufficient horizontal resolution is a possible candidate for this shortcoming. Thus, to investigate what controls the isotopic variability at the synoptic time scales, an isotope-enabled model with much higher horizontal resolution would probably be needed (e.g., Dütsch et al, 2016Dütsch et al, , 2018Moore et al, 2014Moore et al, , 2016.…”

Section: Implications For the Use Of Isotope-enabled Models To Study mentioning

confidence: 99%

Variability of Isotope Composition of Precipitation in the Southeastern Tibetan Plateau from the Synoptic to Seasonal Time Scale

Shi

Risi

et al. 2020

JGR Atmospheres

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Daily precipitation samples were collected at four sites in Mount Yulong and Mount Meili regions of southeastern Tibetan Plateau and analyzed for isotopic composition. Combined with water vapor isotopic composition derived from satellites data (Infrared Atmospheric Sounding Interferometer, Tropospheric Emission Spectrometer, and Greenhouse gases Observing Satellite), the factors controlling the variability in the isotopic composition of precipitation are investigated at the synoptic, intraseasonal, and seasonal time scales. At the seasonal scale, the isotope composition in precipitation is controlled by processes along air mass trajectories affecting the water vapor at the large scale (>200 km), especially upstream deep convection and air mass origin, and by local processes transforming the large‐scale water vapor isotopic composition into the precipitation composition, especially rain evaporation and local circulation. At the intraseasonal and synoptic scales, the isotope composition in precipitation is mainly controlled by these local processes. The shorter the time scale of isotopic variations, the smaller the spatial imprint of these variations. The fact that different factors control the isotopic variability at different time scales calls for caution when applying relationships observed at these time scales to interpret isotopic variations at paleoclimatic time scales. While general circulation models successfully capture the isotopic variability and its controlling factors at the seasonal scale, it fails to simulate them at shorter time scales, because it fails to simulate the local processes.

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Microphysical controls on the isotopic composition of wintertime orographic precipitation

Cited by 32 publications

References 70 publications

Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ¹⁸O/δ²H in South‐Central Alaska

Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ¹⁸O/δ²H in South‐Central Alaska

Tracking the Strength of the Walker Circulation With Stable Isotopes in Water Vapor

Variability of Isotope Composition of Precipitation in the Southeastern Tibetan Plateau from the Synoptic to Seasonal Time Scale

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Microphysical controls on the isotopic composition of wintertime orographic precipitation

Cited by 32 publications

References 70 publications

Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ18O/δ2H in South‐Central Alaska

Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ18O/δ2H in South‐Central Alaska

Tracking the Strength of the Walker Circulation With Stable Isotopes in Water Vapor

Variability of Isotope Composition of Precipitation in the Southeastern Tibetan Plateau from the Synoptic to Seasonal Time Scale

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Resources

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Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ¹⁸O/δ²H in South‐Central Alaska

Synoptic and Mesoscale Mechanisms Drive Winter Precipitation δ¹⁸O/δ²H in South‐Central Alaska