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The stability of marine ice sheets and outlet glaciers is mostly controlled by the dynamics of their grounding line, i.e., where the bottom contact of the ice changes from bedrock or till to ocean water. The last report of the Intergovernmental Panel on Climate Change has clearly underlined the poor ability of models to capture the dynamics of outlet glaciers. Here we present computations of grounding line dynamics on the basis of numerical solutions of the full Stokes equations for ice velocity, coupled with the evolution of the air ice– and sea ice–free interfaces. The grounding line position is determined by solving the contact problem between the ice and a rigid bedrock using the finite element code Elmer. Results of the simulations show that marine ice sheets are unstable on upsloping beds and undergo hysteresis under perturbation of ice viscosity, confirming conclusions from boundary layer theory. The present approach also indicates that a 2‐D unconfined marine ice sheet sliding over a downsloping bedrock does not exhibit neutral equilibrium. It is shown that mesh resolution around the grounding line is a crucial issue. A very fine grid size (<100 m spacing) is needed in order to achieve consistent results.

We apply a three-dimensional (3D) full-Stokes model to simulate the evolution of Da Anglong Glacier, a large glacier in the western Tibetan Plateau from the year 2016 to 2098, using projected temperatures and precipitations from the 25-km-resolution RegCM4 nested within three Earth System Models (ESM) simulating the RCP2.6 and RCP8.5 scenarios. The surface mass balance (SMB) is estimated by the degree-day method using a quadratic elevation-dependent precipitation gradient. A geothermal flux of 60 mW m-2 produces a better fit to measured surface velocity than lower heat fluxes and represents a new datum in this region of sparse heat flux observations. The ensemble mean simulated glacier volume loss during 2016–2098 amounts to 38% of the glacier volume in the year 2016 under RCP2.6 and 83% under RCP8.5. Simulation from 2016 to 2098 without ice dynamics leads to an underestimation of ice loss of 22–27% under RCP2.6 and 16–24% under RCP8.5, showing that ice dynamics play an important amplifying factor in ice loss for this glacier, unlike for small Tibetan glaciers where SMB dominates glacier change.

A digital-correlation full-polarized microwave radiometer is an important passive remote sensor, as it can obtain the amplitude and phase information of an electromagnetic wave at the same time. It is widely used in the measurement of sea surface wind speed and direction. Its configuration is complicated, so the error analysis of the instrument is often difficult. This paper presents a full-polarized radiometer system model that can be used to analyze various errors, which include input signal models and a full-polarized radiometer (receiver) model. The input signal models are generated by WGN (white Gaussian noise), and the full-polarized radiometer model consists of an RF front-end model and digital back-end model. The calibration matrix is obtained by solving the overdetermined equations, and the output voltage is converted into Stokes brightness temperature through the calibration matrix. Then, we use the four Stokes parameters to analyze the sensitivity, linearity, and calibration residuals, from which the simulation model is validated. Finally, two examples of error analysis, including gain imbalance and quantization error, are given through a simulation model. In general, the simulation model proposed in this paper has good accuracy and can play an important role in the error analysis and pre-development of the fully polarized radiometer.

The present study presents a comprehensive analysis of effects of porous fins on mixed convection heat transfer in lid-driven square cavities, where the top lid has the two-way movement. Porous medium with varying permeability, instead of the solid one, could widely modify its baffling effect on fluid flow and could also be utilized to control fluid flow and heat transfer. Fluid flow within the cavity was solved through the Navier–Stokes equations, while that within a saturated porous medium was governed by the Darcy–Forchheimer model. Numerical results indicate that the adding porous fins with excellent permeability could enhance heat transfer dramatically, especially for more fins. The rate of heat transfer enhancement due to an increase in Darcy number decreases, and similar trends were observed for the quantitative variations of porous fins. Besides, positions of porous fins have significant effects on fluid flow and heat transfer. The correlations of average Nusselt numbers, as functions of various governing parameters, have been proposed. The present investigations could be beneficial to the design of the microelectronic cooling through the installation of porous-alike materials or modules.