Abstract

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.

中文翻译：

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对流条件下近地表温度脉动结构研究

摘要

在夏季炎热天气条件下，使用空间和高度分布的线传感器测量沙漠地区近地表空气层的温度脉动，记录频率为 1000 Hz。对于功率谱，对于低于“–5/3”惯性区间区域的频率，记录了值从“–1”到“–1.35”（比例尺：0.2−2 m）的斜率。在惯性区间以上的频率（尺度：0.01−0.1 m），斜率范围从“–4.2”到“–5.8”。在频率低于 0.1-0.3 Hz 的某些事件中，斜率从“–0.2”到“–0.85”。根据 Boussinesq 近似中的运动方程，获得了观测到的光谱斜率的估计值：“–1”、“–4/3”和“–7/3”，这是热分层介质的典型特征。使用不同信号平均时间（1、10、200 s）的定性（视觉）方法，揭示了时间长度为 0.3-1 s 的热对流斜坡结构的出现，它们构成了长度为 1-10 的斜坡s 在较大的平均值。