Modify the Nalli infrared snow emissivity model to also be used for ice

[wx20jjung]

Nick Nalli developed an infrared snow emissivity model with frequency, scan angle, temperature and grain size dependencies. This same model can be used for ice. Could the CRTM be modified to use Nick's infrared snow emissivity model for ice?

(From Nick Nalli)
Michelle Loveless et al. published a paper in 2024 that showed independent comparisons of various models against their field observations of snow and ice using their well-calibrated ARI instrument, and the NOAA snow/ice emissivity model (the one that we developed) compared favorably with those observations down to 200 cm-1. These were in addition to the validation performed in the original MDPI Remote Sensing paper.

Yes, it’s actually a “snow/ice” model, where “ice” is effectively modeled as large particle sizes. Just use the maximum size in the model, which I believe is 1000 micron radius. And yes, it will have both angle and temperature dependence.

[BenjaminTJohnson]

Here's the structural difference. Key task would be to convert the IRsnow structure to IRice structure, which would require converting emissivity to reflectance, and sorting out what to do about temperature dependence.

netcdf NPOESS.IRice.EmisCoeff {                               | netcdf Nalli2.IRsnow.EmisCoeff {
dimensions:                                                     dimensions:
        n_Frequencies = 20 ;                                  |         n_Angles = 10 ;
        n_Surface_Types = 1 ;                                 |         n_Frequencies = 119 ;
        String_Length = 80 ;                                  |         n_Grain_Sizes = 15 ;
                                                              >         n_Temperature = 5 ;
variables:                                                      variables:
        char Surface_Type(n_Surface_Types, String_Length) ;   |         double Angle(n_Angles) ;
                Surface_Type:long_name = "Surface Type" ;     |                 Angle:_FillValue = NaN ;
                Surface_Type:description = "Surface Type" ;   |                 Angle:long_name = "Angle" ;
                Surface_Type:units = "N/A" ;                  |                 Angle:description = "Angle (Z) dimension valu
                Surface_Type:_FillValue = "" ;                |                 Angle:units = "degrees from vertical" ;
        int Surface_Type_IsValid(n_Surface_Types) ;           <
                Surface_Type_IsValid:long_name = "Surface Typ <
                Surface_Type_IsValid:description = "Surface T <
                Surface_Type_IsValid:units = "N/A" ;          <
                Surface_Type_IsValid:_FillValue = 0 ;         <
        double Frequency(n_Frequencies) ;                               double Frequency(n_Frequencies) ;
                                                              >                 Frequency:_FillValue = NaN ;
                Frequency:long_name = "Frequency" ;                             Frequency:long_name = "Frequency" ;
                Frequency:description = "Frequency" ;         |                 Frequency:description = "Frequency (F) dimens
                Frequency:units = "cm^-1" ;                   |                 Frequency:units = "inverse centimeters (cm^-1
                Frequency:_FillValue = -999. ;                |         double Grain_Size(n_Grain_Sizes) ;
        double Reflectance(n_Surface_Types, n_Frequencies) ;  |                 Grain_Size:_FillValue = NaN ;
                Reflectance:long_name = "Reflectance" ;       |                 Grain_Size:long_name = "Grain_Size" ;
                Reflectance:description = "Reflectance" ;     |                 Grain_Size:description = "Snow grain size (R)
                Reflectance:units = "N/A" ;                   |                 Grain_Size:units = "effective radius in micro
                Reflectance:_FillValue = -999. ;              |         double Temperature(n_Temperature) ;
                                                              >                 Temperature:_FillValue = NaN ;
                                                              >                 Temperature:long_name = "Temperature" ;
                                                              >                 Temperature:description = "Temperature (T) di
                                                              >                 Temperature:units = "Kelvins" ;
                                                              >         double Emissivity(n_Temperature, n_Grain_Sizes, n_Fre
                                                              >                 Emissivity:_FillValue = NaN ;
                                                              >                 Emissivity:long_name = "Emissivity" ;
                                                              >                 Emissivity:description = "Spectral water surf
                                                              >                 Emissivity:units = "N/A" ;

// global attributes:                                           // global attributes:
                :creation_date_and_time = "2022/06/13, 15:40: |                 :Description = "Thermal-IR to Far-IR Snow Sur
                :Release = 3 ;                                |                 :Date = "26-Apr-2023" ;
                :Version = 1 ;                                |                 :Notes = "Hybrid Physical Model based Wiscomb
                :Classification_Name = "NPOESS" ;             |                 :Author = "N. R. Nalli, NOAA/NESDIS/STAR" ;
                                                              >                 :Tdep = "refind" ;
                                                              >                 :REF_IND = "Iwabuchi-Yang11" ;
                                                              >                 :ref_ind = -1. ;
                                                              >                 :Dimensions = "n_Temperature x n_Grain_Sizes
                                                              >                 :Reference1 = "Wiscombe and Warren (1980), J.
                                                              >                 :Reference2 = "Dozier and Warren (1982), Wate
                                                              >                 :Reference3 = "Iwabuchi and Yang (2011), J. Q
                                                              >                 :Reference4 = "Hori et al. (2013), Appl. Opti
                                                              >                 :History = "Version 1.1 LUT written to NetCDF
                                                              >                 :Release_Offline = "2." ;
                                                              >                 :Version_Offline = "1.1" ;
                                                              >                 :Version = 2 ;
                                                              >                 :Release = 1 ;
                                                              >                 :Classification_Name = "Nalli" ;
}                                                               }