Andrew Rees

Multiple-Layer Adaptation of HUT Snow Emission Model: Comparison With Experimental Data

Modeling of snow emission at microwave frequencies is necessary in order to understand the complex relations between the emitted brightness temperature and snowpack characteristics such as density, grain size, moisture content, and vertical structure. Several empirical, semiempirical, and purely theoretical models for the prediction of snow emission properties have been developed in recent years. In this paper, we investigate the capability of one such model to simulate snow emission during the peak snow season-a new multilayer version of the Helsinki University of Technology (HUT) snow model. Developed with a single layer, the original HUT model was easily applied over large geographic areas for the estimation of snow cover characteristics by model inversion. A single homogenous layer, however, may not accurately allow the simulation of vertically structured natural snowpacks. The new modification to the model allows the simulation of emission from a snowpack with several snow or ice layers, with the individual component layers treated as in the original HUT model. The results of modeled snowpack emission, using both the original model and the new multilayer modification, are compared with reference measurements made using ground-based radiometers deployed in Finland and Canada. Detailed in situ measurements of the snowpack are used to set the model inputs. We show that, in most cases, use of the multiple-layer model improves estimates for the higher frequencies tested, with up to 38% improvement in rms error. In some cases, however, the use of the multiple-layer model weakens model performance particularly at lower frequencies.

Correction to “Multiple-Layer Adaptation of HUT Snow Emission Model: Comparison With Experimental Data” [Jul 10 2781-2794]

In the above titled paper (ibid., vol. 48, no. 7, pp. 2781-2794, Jul. 10), there is an error in Section II-B, which is corrected here.

Comparison of multiple layer snow emission models

Modeling of snow emission at microwave frequencies is necessary in order to understand the relationships between the emitted brightness temperature and snowpack characteristics. Several empirical, semi-empirical and purely theoretical models for this purpose have been developed in recent years. This study compares the performance of two widely used semi-empirical models against experimental datasets of surface based radiometer measurements, coupled with snow stratigraphy observations from several sites in Finland and Canada. The results of the study emphasize the importance of careful inclusion of snow stratigraphy in simulations. Both models used are able to produce the measured brightness temperatures with sufficient accuracy; some differences and trends in modeling errors can be noted. However, using the presented datasets neither of the models perform conclusively better than the other when considering all observed channels.