Temperature profile snapshot through the first 20cm below the sand surface (horizontal dashed line) recorded in March 2011. The ordinate is depth in mm, and the abscissa is temperature in C. Circles represent measurements, with symbol size equal to actual sensor diameter. The thick red line is the prediction of our 1D thermal model. The dashed and solid blue lines correspond to the uncertainty range for measured shear velocity. The blue horizontal arrow and orange thermometer show, respectively, wind speed and ambient temperature. The lower bar marks progression over the nearly two days of this experiment, with orange segments between sunrise and sunset. Time is legal Qatar time (UT+3 hours). The left and  right vertical arrows indicate measured net radiation and calculated thermal convection fluxes, respectively, counted positive into the dune. For each image, we also display the root-mean-square error between measurement and model over all 15 sensors.