If anyone knows, please contact me. We currently make an effort to investigate soil temperature feedbacks on surface climate over Mongolia using combined statistical and WRF model methods.
From the KNMI explorer (http://climexp.knmi.nl/start.cgi?id=someone@somewhere) you can download all sorts of meteorological data (station, grid, reanalysis).
I am not sure which stations are available for Mongolia but in the worst case you will be able to use gridded or reanalysis data.
You can ask for someone who attends the CEOP Program. I also just evaluated the soil temperature at Mongolia. If you have some interests, you can contact me by email. [email protected]