Lunar Global Surface Temperatures from the Diviner Lunar Radiometer Experiment

Abstract:

Systematic observations of the global thermal state of the Moon and its diurnal variability provide the ability to characterize the surface energy balance of the lunar regolith and how it exchanges and stores heat. The Diviner Lunar Radiometer Experiment (Paige et al., 2010a) on NASA’s Lunar Reconnaissance Orbiter (LRO) has been systematically mapping the global thermal state of the Moon since July of 2009. Early observations have been used to infer the radiative and bulk thermophysical properties of the near-surface regolith at the equator in an average sense (Vasavada et al. 2011). With over five years of data, the density of observations both spatially and in local time is high enough that global diurnal temperatures can be adequately resolved to create global maps of surface temperatures which will provide insight into the radiative and thermophysical properties of the lunar regolith globally.

We have compiled all nadir observations of radiance from the seven Diviner infrared spectral channels to derive global bolometric brightness temperatures, a measure of the spectrally integrated flux of infrared radiation emerging from the surface (Paige et al., 2010b), as a function of local time. With this data set, we generate instantaneous global maps of surface temperatures for any arbitrary subsolar longitude and can now provide “snap-shots” of the lunar surface temperatures through an entire lunation at 0.5 degree map resolution. We also generate global temperature maps for any given hour of local time. Hourly nighttime maps reveal global cooling of the lunar surface providing information about the vertical profile of the lunar regolith as sensible heat absorbed during the lunar day is radiated to space during the long lunar night from greater depths.

References

Paige, D. A., et al. (2010a) The Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment, Space Sci. Rev., 150, 125-160.

Paige, D. A., et al. (2010b) Diviner Lunar Radiometer observations of cold traps in the Moon’s south polar region, Science, 330, 479-482.

Vasavada, A. R., et al. (2012) Lunar equatorial surface temperatures and regolith properties from the Diviner Lunar Radiometer Experiment, J. Geophys. Res., 117, E00H18, doi:10.1029/2011JE00398