The Role of Atmospheric Rivers for Extreme Ablation and Snowfall Events in the Southern Alps of New Zealand

Little, K.; Kingston, Daniel G.; Cullen, Nicolas J.; Gibson, Peter B.

doi:10.1029/2018gl081669

Cited by 41 publications

(48 citation statements)

References 37 publications

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“…In contrast to the composite mean, a significant moisture flux (daily mean IVT approaching 500 kg·m −1 ·s −1 ) resembling an atmospheric river structure can be observed during the largest snowfall event on 13 July 2012 (Figures c and d), demonstrating how important individual, moisture‐laden air masses can be in controlling snowfall during the cool season. While it is beyond the scope of this study to provide a comprehensive analysis of the atmospheric conditions associated with individual snowfall events, it is the focus of a companion study by Little et al ().…”

Section: Resultsmentioning

confidence: 99%

The Influence of Weather Systems in Controlling Mass Balance in the Southern Alps of New Zealand

et al. 2019

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The recent advance of some fast‐responding glaciers in New Zealand demonstrates that regional variability in atmospheric circulation can counteract the effects of global warming. Until recently, a key challenge in quantifying how weather systems influence glaciers has been the lack of observational data from high‐elevation sites in the Southern Alps. Using high‐quality meteorological and glaciological observations from Brewster Glacier over four summers and two winters, a physically based mass balance model is used to resolve daily ablation and solid precipitation. Composite analysis confirms ablation is largely controlled by changes in meridional airflow, with high ablation associated with north to northwest airflow, while low ablation is associated with south to southwest airflow. The largest snowfall events in the cool season also occur during northwesterly airflow, highlighting the importance of seasonality (i.e., whether an event occurs in the ablation or accumulation period) for mass balance. Application of a synoptic weather typing approach commonly used for the New Zealand region, known broadly as Kidson weather types, revealed that three established regimes (trough, zonal, and blocking) are less effective in resolving variability in ablation and snowfall than a simple procedure that groups weather types using geostrophic flow direction. The frequency of four weather types can explain approximately 40% of the variance in mass balance over a 42‐year period. This highlights that future regional variability or trends in large‐scale circulation and their seasonality, superimposed on background warming, will be important in shaping glacier mass balance in the coming decades.

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Section: Resultsmentioning

confidence: 99%

The Influence of Weather Systems in Controlling Mass Balance in the Southern Alps of New Zealand

et al. 2019

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“…This is particularly evident for atmospheric rivers: long, narrow bands of intense horizontal moisture transport within the warm sector of extratropical cyclones 227,228 that are linked with flooding, [229][230][231][232] changes in terrestrial water storage, 233 and the mass balance of glaciers and snowpack. [234][235][236][237] Assuming minor changes in dynamical characteristics, it is expected that increased atmospheric moisture flux will intensify atmospheric river events. [238][239][240][241] However, changes in location, orientation, and dynamical aspects relating to wind speed will dominate responses in some regions.…”

Section: Changes In Characteristics Of Precipitation and Hydrologymentioning

confidence: 99%

Advances in understanding large‐scale responses of the water cycle to climate change

Allan

Barlow

Byrne

et al. 2020

Annals of the New York Academy of Sciences

361

153

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Globally, thermodynamics explains an increase in atmospheric water vapor with warming of around 7%/°C near to the surface. In contrast, global precipitation and evaporation are constrained by the Earth's energy balance to increase at ∼2-3%/°C. However, this rate of increase is suppressed by rapid atmospheric adjustments in response to greenhouse gases and absorbing aerosols that directly alter the atmospheric energy budget. Rapid adjustments to forcings, cooling effects from scattering aerosol, and observational uncertainty can explain why observed global precipitation responses are currently difficult to detect but are expected to emerge and accelerate as warming increases and aerosol forcing diminishes. Precipitation increases with warming are expected to be smaller over land than ocean due to limitations on moisture convergence, exacerbated by feedbacks and affected by rapid adjustments. Thermodynamic increases in atmospheric moisture fluxes amplify wet and dry events, driving an intensification of precipitation extremes. The rate of intensification can deviate from a simple thermodynamic response due to in-storm and larger-scale feedback processes, while changes in large-scale dynamics and catchment characteristics further modulate the frequency of flooding in response to precipitation increases. Changes in atmospheric circulation in response to radiative forcing and evolving surface temperature patterns are capable of dominating water cycle changes in some regions. Moreover, the direct impact of human activities on the water cycle through water abstraction, irrigation, and land use change is already a significant component of regional water cycle change and is expected to further increase in importance as water demand grows with global population.

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“…ARs act as bridges or conveyors between oceanic evaporation and continental precipitation 12 , 13 , the former being the main origin of water vapor that reaches land masses at extratropical latitudes. ARs have also been linked with changes in water storage and the mass balance of ice sheets, glaciers, and snowpack 14 , 15 . The current relentless rise in global mean surface temperature is closely linked to the increase in atmospheric water vapor 16 , 17 , and the greater availability of water vapor favors a larger transport of moisture, and hence an intensification of extreme precipitation events and floods triggered by ARs 18 – 20 .…”

Section: Introductionmentioning

confidence: 99%

Significant increase of global anomalous moisture uptake feeding landfalling Atmospheric Rivers

et al. 2020

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One of the most robust signals of climate change is the relentless rise in global mean surface temperature, which is linked closely with the water-holding capacity of the atmosphere. A more humid atmosphere will lead to enhanced moisture transport due to, among other factors, an intensification of atmospheric rivers (ARs) activity, which are an important mechanism of moisture advection from subtropical to extra-tropical regions. Here we show an enhanced evapotranspiration rates in association with landfalling atmospheric river events. These anomalous moisture uptake (AMU) locations are identified on a global scale. The interannual variability of AMU displays a significant increase over the period 1980-2017, close to the Clausius-Clapeyron (CC) scaling, at 7 % per degree of surface temperature rise. These findings are consistent with an intensification of AR predicted by future projections. Our results also reveal generalized significant increases in AMU at the regional scale and an asymmetric supply of oceanic moisture, in which the maximum values are located over the region known as the Western Hemisphere Warm Pool (WHWP) centred on the Gulf of Mexico and the Caribbean Sea.

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The Role of Atmospheric Rivers for Extreme Ablation and Snowfall Events in the Southern Alps of New Zealand

Cited by 41 publications

References 37 publications

The Influence of Weather Systems in Controlling Mass Balance in the Southern Alps of New Zealand

The Influence of Weather Systems in Controlling Mass Balance in the Southern Alps of New Zealand

Advances in understanding large‐scale responses of the water cycle to climate change

Significant increase of global anomalous moisture uptake feeding landfalling Atmospheric Rivers

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