No abstract

Abstract:Brightness temperature T B data were collected with a surface-based radiometer operating on both vertical and horizontal polarizations at frequencies of 19, 37, and 85 GHz. Both microwave emissions and thermophysical data were collected as part of the Collaborative-Interdisciplinary Cryospheric Experiment between 15 May and 25 June 2000, in the Canadian High Arctic. Each season was characterized by a running variance of the time series in the microwave emissions. The seasonal analysis was conducted through observed changes in the physical characteristics of the sea ice and the overlying snow pack. Results from a k-means clustering analysis show that variability in the microwave response can be categorized into phenomenological states that were described by Livingstone et al. [IEEE Transactions on Geoscience and Remote Sensing 1987; 25(2): 174-187] as winter, early melt, melt onset and advanced melt. We describe the average thermophysical conditions associated with each one of these 'ablation states' and interpret the relative contributions of each to the observed microwave response. Emissivities were calculated and used as part of a descriptive analysis of the seasonal variation of T B . Our results confirm other findings that the strength and pattern of the relationship are frequency dependent and relative to snow and ice dielectric properties. Useful information on the thermodynamic state of the snow-sea-ice system can be derived from passive microwave data, since the microwave emissions respond to the general seasonal changes associated with the transition from winter to a melt ponded sea ice surface.

No abstract

No abstract