dimensions:
        lon = 96 ;
        lat = 80 ;
        lonb = 97 ;
        latb = 81 ;
        sigma_full = 14 ;
        sigma_half = 15 ;
        time = UNLIMITED ; // (192 currently)


float black_carbon(time, sigma_full, lat, lon) ;
                black_carbon:_FillValue = -999.f ;
                black_carbon:units = "kg/m^2" ;