The lunar polar regions offer permanently shadowed regions (PSRs) representing the only regions which are cold enough for water ice to accumulate on the surface. The Lunar Exploration Neutron Detector (LEND) aboard the Lunar Reconnaissance Orbiter (LRO) has mapped the polar regions for their hydrogen abundance which possibly resides there in the form of water ice. Neutron suppression regions (NSRs) are regions of excessive hydrogen concentrations and were previously identified using LEND data. At each pole, we applied thermal modeling to three NSRs and one unclassified region to evaluate the correlation between hydrogen concentrations and temperatures. Our thermal model delivers temperature estimates for the surface and for 29 layers in the sub-surface down to 2 m depth. We compared our temperature maps at each layer to LEND neutron suppression maps to reveal the range of depths at which both maps correlate best. As anticipated, we find the three south polar NSRs which are coincident with PSRs in agreement with respective (near)-surface temperatures that support the accumulation of water ice. Water ice is suspected to be present in the upper approximate to 19 cm layer of regolith. The three north polar NSRs however lie in non-PSR areas and are counter-intuitive as such that most surfaces reach temperatures that are too high for water ice to exist. However, we find that temperatures are cold enough in the shallow sub-surface and suggest water ice to be present at depths down to approximate to 35-65 cm. Additionally we find ideal conditions for ice pumping into the sub-surface at the north polar NSRs. The reported depths are observable by LEND and can, at least in part, explain the existence and shape of the observed hydrogen signal. Although we can substantiate the anticipated correlation between hydrogen abundance and temperature the converse argument cannot be made.

In this study, the ground surface temperature (GST) records from 16 meteorological stations, which are located in or adjacent to permafrost regions on the central Qinghai-Tibet Plateau (QTP), are analysed using MannKendal test and Sen's slope estimate methods. We revealed that the GSTs have shown statistically significant warming. On average, mean annual ground surface temperature has increased at a rate of 0.60 degrees C decade1 over the period of 19802007, which is more pronounced than the increase of mean annual air temperature on the plateau. The winter ground surface warming is especially prominent, which is similar to the seasonal trends in changes of air temperature. As important parameters to assess the changes of ground thermal regime in cold regions, surface freezing and thawing indices were also studied. The nonparametric statistic test and estimate indicate that surface freezing and thawing indices both show significant variations (111.2 and 125.0 degrees C d decade1, respectively) on the central QTP. The intensive ground surface warming is responsible for the concurrent increase in permafrost temperatures at the long-term observation sites on the plateau. The close correlations between ground surface and permafrost temperatures indicate that the dramatic ground surface warming could have significant influence on the change of permafrost thermal regime in the study region. Copyright (c) 2012 Royal Meteorological Society