Obtaining surface emissivity at microwave window frequencies over the Arctic sea ice area
Abstract
Despite three decades of passive microwave measurements, applications of those for numerical weather prediction (NWP) over the Arctic sea ice region have been limited due to inaccurate surface emissivity, particularly in the channels sensitive to the surface. In this study, we attempt to improve the surface emissivity estimate of sea ice over microwave spectrum during Arctic winter based on the explicit radiative transfer calculation, which requires detailed knowledge on thermal and optical properties of sea ice. In doing so, we introduce an improved version of one dimensional thermodynamic sea ice model (Tonboe, 2005) forced by ERA-Interim reanalysis. In addition, we apply a nudging technique with small relaxation terms for infrared based skin temperature (OSI-205-a/b) and microwave based snow-ice interface temperature (Lee and Sohn, 2015), so as to constrain the model to follow observations. Preliminary results from the model demonstrate a good agreement of temperature profile and ice depth with CRREL buoy observations. We note that the temperature evolvement with time is significantly improved. Furthermore, the model appears to improve the growth even for the ice thicker than 2 m, which is known to be generated by dynamical processes such as sea ice convergence, in spite of one dimensional thermodynamic model. The results further suggest that the modelling approach developed in this study can lead to an improved surface emissivity estimation because the model better describes thermodynamic and physical features of sea ice.
Based on above results, we h a ve developed a system that combine s the thermodynamic sea ice model with the radiative transfer model, to estimate microwave surface emissivit y at window frequencies. Results are promising, and detailed discussion will be made in the presentation.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C51D1332K
- Keywords:
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- 0744 Rivers;
- CRYOSPHERE;
- 0746 Lakes;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE;
- 0758 Remote sensing;
- CRYOSPHERE