The image above represents an attempt to show changes in the transmissivity of the Martian atmosphere in the northern hemisphere from MOLA's reflectivity measurement. While further corrections are needed to interpret the measurement in a quantitative sense, it is apparent that the near-infrared transmission varies with seasons. The TES instrument on MGS is also showing that the atmosphere is varying over time at thermal infrared wavelengths. The MOLA reflectivity measurement has an accuracy of about 5%. (Credit: MOLA Science Team)