Work

Evaluation of turbulent flux parameterizations over a continental glacier on the Tibetan Plateau

Year: 2026

Type: article

Abstract: A lack of observations of turbulent fluxes over continental glaciers limits our understanding of the mechanisms that control glacier variations and associated water resource changes across the Tibetan Plateau (TP). Here, we present the first comprehensive analysis of turbulent flux characteristics and a systematic evaluation of turbulent flux parameterizations for a continental glacier on the TP, using eddy covariance (EC) observations from the Dunde Glacier during May–October 2023. The Dunde Glacier persistently lost energy through latent heat flux (mean LE : −9.6 W m −2 ) and gained energy via sensible heat flux (mean H : 6.9 W m −2 ), with pronounced seasonal and daily variability. On the basis of these measured data, we tested five turbulent flux parameterizations for the Dunde Glacier, including those derived from katabatic flow models, simplified Monin–Obukhov similarity theory without stability corrections, Monin–Obukhov similarity theory with stability corrections using two different bulk Richardson numbers, and the Monin–Obukhov similarity theory with universal stability functions, with different roughness length parameterizations applied. Within this observation-constrained assessment, the evaluated schemes showed varying degrees of agreement with the EC observations. Considering multiple timescales, the Richardson-number-based approaches showed comparatively balanced agreement with the observations for both H and LE and more closely reproduced the observed diurnal evolution of turbulent fluxes. We further assessed representative parameterizations within energy and mass-balance simulations. The results indicate that recalibration of turbulent-flux parameters improved the simulated surface temperature, surface-height change, and cumulative mass balance, with the Richardson-number-based scheme and the Monin–Obukhov scheme using universal stability functions showing closer agreement with the observations after recalibration. Our findings suggest that, based on observational data available from previous studies, aerodynamic roughness length may exhibit systematic differences among glacier types, with continental glaciers showing a broader range and generally lower values than maritime glaciers. We also found that during the humid heatwave event, the Dunde Glacier experienced a sharp increase in H , while the magnitude of negative LE decreased and LE occasionally reversed direction, shifting the total turbulent heat flux from negative values during non-heatwave conditions to positive values during the humid heatwave. However, none of the evaluated schemes fully reproduced the observed weakening and occasional sign reversal of LE during the humid heatwave, highlighting limitations in representing latent heat exchange under extreme warm and humid conditions. These findings advance our knowledge of turbulent fluxes for continental glaciers on the TP and provide important guidance for the improvement of glacier models.

Source: The cryosphere

DOI: 10.5194/tc-20-6021-2026