The surface energy budget on the debris-covered Koxkar Glacier in China

Yao, Jimin; Gu, Lianglei; Han, Hua; Wang, Yuyu; Liu, Shiyin

doi:10.1007/s12665-014-3350-2

Cited by 8 publications

(10 citation statements)

References 20 publications

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“…day −1 on clear and overcast days, respectively. These values are higher than evaporation rates measured in the Tien Shan where Yao et al (2014) report values between 0.9 and 1.9 mm w.e. day −1 and considerably higher than what has been observed on a debris-covered glacier in the FIGURE 2 | Fluxes and variables measured at the AWS, SW net denoting net shortwave radiation, LW net net longwave radiation, H sensible and LE latent heat flux (A).…”

Section: Turbulent Fluxes From Ec Measurementscontrasting

confidence: 62%

“…Direct measurements of turbulent fluxes require the use of eddy correlation systems, and to our knowledge this has only been attempted twice previously over debris-covered glaciers. Yao et al (2014) find daily latent heat fluxes to be larger than sensible heat fluxes in the Tien Shan. This is the opposite for a site investigated by Collier et al (2014) in the European Alps.…”

Section: Introductionmentioning

confidence: 73%

“…Sensible heat fluxes are comparable to the Tien Shan (Yao et al, 2014) but are lower than in the European Alps (Collier et al, 2014), most plausibly explained by the lower wind speeds as temperature gradients are likely higher in the Himalaya.…”

Section: Turbulent Fluxes From Ec Measurementsmentioning

confidence: 94%

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The Importance of Turbulent Fluxes in the Surface Energy Balance of a Debris-Covered Glacier in the Himalayas

et al. 2018

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Surface energy balance models are common tools to estimate melt rates of debris-covered glaciers. In the Himalayas, radiative fluxes are occasionally measured, but very limited observations of turbulent fluxes on debris-covered tongues exist to date. We present measurements collected between 26 September and 12 October 2016 from an eddy correlation system installed on the debris-covered Lirung Glacier in Nepal during the transition between monsoon and post-monsoon. Our observations suggest that surface energy losses through turbulent fluxes reduce the positive net radiative fluxes during daylight hours between 10 and 100%, and even lead to a net negative surface energy balance after noon. During clear days, turbulent flux losses increase to over 250 W m −2 mainly due to high sensible heat fluxes. During overcast days the latent heat flux dominates the turbulent losses and together they reach just above 100 W m −2. Subsequently, we validate the performance of three bulk approaches in reproducing the observations from the eddy correlation system. Large differences exist between the approaches, and accurate estimates of surface temperature, wind speed, and surface roughness are necessary for their performance to be reasonable. Moreover, the tested bulk approaches generally overestimate turbulent latent heat fluxes by a factor 3 on clear days, because the debris-covered surface dries out rapidly, while the bulk equations assume surface saturation. Improvements to bulk surface energy models should therefore include the drying process of the surface. A sensitivity analysis suggests that, in order to be useful in distributed melt models, an accurate extrapolation of wind speed, surface temperature and surface roughness in space is a prerequisite. By applying the best performing bulk model over a complete melt period, we show that turbulent fluxes reduce the available energy for melt at the debris surface by 17% even at very low wind speeds. Overall, we conclude that turbulent fluxes play an essential role in the surface energy balance of debris-covered glaciers and that it is essential to include them in melt models.

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Section: Turbulent Fluxes From Ec Measurementscontrasting

confidence: 62%

Section: Introductionmentioning

confidence: 73%

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The Importance of Turbulent Fluxes in the Surface Energy Balance of a Debris-Covered Glacier in the Himalayas

et al. 2018

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“…A limited number of measurements of turbulent exchange over debris-covered ice (Collier and others, 2014; Yao and others, 2014; Steiner and others, 2018) indicate that these fluxes play a non-negligible role in the surface energy balance of debris-covered glaciers, and moisture fluxes through processes of ventilation of the debris cover also provide an explanation of the characteristic shape of the Østrem curve of ice ablation as a function of debris thickness (Evatt and others, 2015). Treatment of debris-covered ice in coupled glacier land surface–atmosphere models shows that the altered surface properties of the debris-covered parts of the glacier impact the overlying atmosphere at a regional scale (Collier and others, 2015), and such feedbacks may become more important to mountain weather as debris-covered ice areas expand to affect a greater proportion of the glacierized area.…”

Section: Introductionmentioning

confidence: 99%

Comparison of turbulent structures and energy fluxes over exposed and debris-covered glacier ice

Nicholson

Stiperski

2020

J. Glaciol.

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We present the first direct comparison of turbulence conditions measured simultaneously over exposed ice and a 0.08 m thick supraglacial debris cover on Suldenferner, a small glacier in the Italian Alps. Surface roughness, sensible heat fluxes (~20–50 W m−2), latent heat fluxes (~2–10 W m−2), topology and scale of turbulence are similar over both glacier surface types during katabatic and synoptically disturbed conditions. Exceptions are sunny days when buoyant convection becomes significant over debris-covered ice (sensible heat flux ~ −100 W m−2; latent heat flux ~ −30 W m−2) and prevailing katabatic conditions are rapidly broken down even over this thin debris cover. The similarity in turbulent properties implies that both surface types can be treated the same in terms of boundary layer similarity theory. The differences in turbulence between the two surface types on this glacier are dominated by the radiative and thermal contrasts, thus during sunny days debris cover alters both the local surface turbulent energy fluxes and the glacier component of valley circulation. These variations under different flow conditions should be accounted for when distributing temperature fields for modeling applications over partially debris-covered glaciers.

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“…However these approaches remain limited in their scope as they cannot adequately address the spatial and temporal distribution of surface and meteorological variables. This is because atmospheric field observations on debris-covered tongues are limited to only a few field locations in the Himalaya (Lejeune et al, 2013;Ragettli et al, 2013;Rounce et al, 2015;Steiner et al, 2018), the Karakoram (Mihalcea et al, 2008) and the Tien Shan (Yao et al, 2014). All of these studies cover relatively short time spans ranging from days to multiple months.…”

Section: Introductionmentioning

confidence: 99%

The multi-scale interaction between the atmosphere, cryosphere and extreme topography in High Mountain Asia

Bonekamp¹

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The surface energy budget on the debris-covered Koxkar Glacier in China

Cited by 8 publications

References 20 publications

The Importance of Turbulent Fluxes in the Surface Energy Balance of a Debris-Covered Glacier in the Himalayas

The Importance of Turbulent Fluxes in the Surface Energy Balance of a Debris-Covered Glacier in the Himalayas

Comparison of turbulent structures and energy fluxes over exposed and debris-covered glacier ice

The multi-scale interaction between the atmosphere, cryosphere and extreme topography in High Mountain Asia

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