Updates: On March 2021, the datasets in 1-3 have been updated with sea ice fraction considered over the polar regions for all the months. The new datasets are tagged as version2.
Download Data: We provide the data set in the following formats.
1. The spectral emissivity for the RRTMG_LW bands (download)
2. The spectral emissivity for the Fu-Liou bands (download)
3. The spectral emissivity at a 1cm-1 resolution for the entire LW spectrum (24G in total, download)
Data format: The data is in the NetCDF file with self-explanatory notes.
- For Formats 1-3, the surface spectral emissivity is provided for each 0.5o-by-0.5o grid box and for each calendar month.
- For Format 1-2, the spectral emissivity is averaged onto the bandwidths defined in the radiation scheme.
- For Formats 3-4, the spectral emissivity is presented in 1cm-1 spectral resolution but please do note the actual spectral resolution is dictated by the spectral resolution of the index of refraction of the materials available for our calculation.
- The surface emissivity in general is a function of the zenith angle. The emissivity at 53o is used in our data set since this is the angle for diffusivity approximation. The emissivity at other zenith angles can be provided upon request as well.
Note: For Formats 1-3, the surface spectral emissivity over lands is derived according to Huang et al. (2016). The surface spectral emissivity is just that of open water, regardless of sea ice coverage or not. If you need surface spectral emissivity of sea ice, you can get it from Formats 4 and construct a new surface spectral emissivity based on your own sea ice map.
Brief Description: This data set is intended for use in the GCM and NWP models. The spectral surface emissivity of different surface types has been modeled using the first principle. The development of the dataset is anchored on MODIS retrieval and then validated against IASI retrievals. The details can be found in Huang et al. (2016). A unique feature of this data set is the coverage of the far-IR spectrum region. If you want to be on the mailing list for any updates on the spectral emissivity dataset, please email me with “subscribe emissivity” on the title.
Acknowledgments: The work that led to the production of the data set has been supported by the DoE BER Division SciDA program and NASA Earth Sciences Program. Should you have any questions, please email me. References:
- Chen, X. H., X. L. Huang, M. G. Flanner, Sensitivity of modeled far-IR radiation budgets in polar continents to treatments of snow surface and ice cloud radiative properties, Geophysical Research Letters, 41(18), 6530-6537, doi:10.1002/2014GL061216, 2014.
- Huang, X. L., X.H. Chen, D. K. Zhou, X. Liu, An observationally based global band-by-band surface emissivity dataset for climate and weather simulations, Journal of the Atmospheric Sciences, 73, 3541-3555, doi:10.1175/JAS-D-15-0355.1, 2016.