On the Structure of Temperature Pulsations near the Surface under Convective Conditions

Temperature pulsations are measured under conditions of summer hot weather in the near-surface air layer in a desert territory using wire sensors distributed spatially and in height with a recording frequency of 1000 Hz. For the power spectra, slopes with values from "-1" to "-1.35" (scales: 0.2-2 m) are recorded for frequencies below the "-5/3" inertial interval region. At frequencies above the inertial interval (scales: 0.01-0.1 m), slopes range from "-4.2" to "-5.8." In some episodes at frequencies less than 0.1-0.3 Hz, there are slopes from "-0.2" to "-0.85." Based on the equations of motion in the Boussinesq approximation, estimates are obtained for the observed slopes of the spectra: "-1," "-4/3," and "-7/3" that are typical of a thermally stratified medium. Using a qualitative (visual) method at different signal averaging times (1, 10, 200 s), the emergence of thermoconvective ramp structures with a temporal length of 0.3-1 s is revealed, which constitute a ramp with a length of 1-10 s at larger averaging.