New Diviner Seasonal Polar Data Products
New Diviner data products have been released on the Diviner PDS data archive this week. A decade of Diviner infrared radiance measurements of the Moon were compiled into polar stereographic maps of temperatures poleward of 80° latitude at fixed local times and fixed subsolar longitudes to provide an overview of diurnal temperatures of the polar regions. The data have been divided into winter and summer seasons, defined by the times of year when the subsolar latitude is above or below the equator, to characterize the variations in seasonal temperatures. Since the illumination in the polar regions is perpetually at grazing angles, topography plays a dominate role in surface temperatures. Consequently, the surface and near-surface thermal environment can vary in complex ways with time of day and season, which produces areas that are seasonally shadowed for prolonged periods. These seasonally shadowed regions are much more extensive than the permanently shadowed regions (PSRs). We find that surfaces below 110 K, capable of cold trapping water over a billion years, more than doubles in the winter for the south polar regions, and more than quadruples in the winter for the north polar regions.
Figure: Maximum summer and winter temperatures for the south polar region to 80°S latitude derived from polar data products with 110 K contoured with a black line (From Williams et al., JGR, 2019).
This data has been released as a new level 4 data product type, Polar Cumulative Products (PCP), formatted as simple ASCII tables with additional raster files and browse images available here. The data was produced by binning Diviner RDR (Level 1b) radiance measurements for each IR channel (channels 3-9) in 240 meter bins of a polar stereo projected grid, in increments of 0.25 hours of local time, or 3.75 degrees of subsolar longitude, to determine the mean bolometric brightness temperatures over a 10 degree latitudinal cap covering each pole. For more details see: Williams, J.-P., et al. (2019), Seasonal polar temperatures on the Moon, J. Geophys. Res., 124, 2505–2521, https://doi.org/10.1029/2019JE006028