1. The problem statement, all variables and given/known data A satellite infrared radiometer (λ = 10 micrometer, footprint size 5x5 km) is observing a region of mixed open water and ice covered sea surface, where the temperature of the open water is -1 degree celsius and that of the sea ice -7 degree celsius. In the infrared, sea ice can be assumed as blackbody, while open water has an emissivity of about 0.8. Neglect any interference of the atmosphere What is the brightness temperature if the pixel contains 30 % pure open water and 70 % sea ice ? 2. Relevant equations Tb^-1 = k/(h*v)*ln[1+e^((h)(v)/((k)(T))-1)/ε] ε = 1 for a black body 3. The attempt at a solution i got the observed brighness temperature for pure water to be 261.049 K and 266.0000846 K for pure sea ice (Expected value) E(ξ) = 0.3*261.049 + 0.7*266.0000846 = 264.514 K This is not valied since it is Rayleigh-Jeans , Why ? It should by Planck but i dont know the intensity ?