Abstract

The height of the mixing layer is a significant parameter for describing the dynamics of the planetary boundary layer (PBL), especially for air quality control and for the parametrizations in numerical modeling. The problem is that the heights of the mixing layer cannot be measured directly. The values of this parameter are depending both on the applied algorithms for calculation and on the measuring instruments which have been used by the data source. To determine the height of a layer of intense turbulent heat exchange, data were used from acoustic meteorological locator (sodar) and from a passive single-channel scanning microwave radiometer MTP-5 (MWR) to measure the temperature profile in a layer of up to 1 km. Sodar can provide information on the structure of temperature turbulence in the PBL directly. These data have been compared with the mixing layer height calculated with the Parcel method by using the MTP-5 data. For the analysis, July and September 2020 were selected in the city of Tomsk in Siberia as characteristic periods of mid-summer and the transition period to autumn. The measurement results, calculations and inter-comparisons are shown and discussed in this work. During temperature inversions in the boundary layer, it was observed that turbulent heat transfer (increased dispersion of air temperature) is covering the inversion layers and the overlying ones. Moreover, this phenomenon is not only occurring during the morning destruction of inversions, but also in the process of their formation and development.

Highlights

  • A lot of experimental and theoretical works are devoted to the study of the processes occurring in the planetary boundary layer (PBL) of the atmosphere

  • For days with good weather, the PBL has a well-defined structure and diurnal cycle [1,38], which leads to the development of a convective boundary layer (CBL), called a mixing layer, during the day and a stable boundary layer (SBL) at night [1]

  • [1,38], which leads to the development of a convective boundary layer (CBL), called ofcan a mixing layer, during the day and a stable boundary layer (SBL) at night [1]

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Summary

Introduction

A lot of experimental and theoretical works are devoted to the study of the processes occurring in the planetary boundary layer (PBL) of the atmosphere. We used data from active acoustic sounding (sodar) and passive single of 15 channel scanning microwave radiometer (MWR) to compare PBL characteristics and determine their relationship during the month July and later in September when the season changes. The purpose of this work was to determine the mixing layer height in the PBL termine relationship during monthofJuly later in September the measureseason during itstheir diurnal evolution, the the analysis theand temperature profiles when over the changes. The mixing layer height according to the sodar measurements the characteristics of temperature profiles. Temperature profiles was determined as the layer height with increased dispersion of air The temperature

Photo ofofthe profilerMTP-5
Temperature Regime of the Experiment Period
PBL Parameters byLSodar
PBL from
PBL Characteristics from Temperature Stratification Data
Distribution
SBL Characteristics
Diurnal variation ofof the
11. Distribution
Mixing
Mixing Layer Height Characteristics in the Case of CBL
Findings
Conclusions
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