Abstract
Atmosphere boundary layer (ABL or BL) acts as a pivotal part in the climate by regulating the vertical exchange of moisture, aerosol, trace gases and energy between the earth surface and free troposphere (FT). However, compared with research on the exchange between earth surface and ABL, there are fewer researches on the exchange between ABL and FT, especially when it comes to the quantitative measurement of vertical exchange flux between them. In this paper, a number of various methodologies for investigating the exchange of the substance and energy between ABL and FT are reviewed as follows: (1) methods to obtain entrainment rate, which include method by investigating the height of inversion layer, method of flux-jump, estimating with dataset from the ASTEX Lagrangian Experiments and method of using satellite observations and Microwave Imager; (2) mass budget method, which can yield quantitative measurements of exchange flux between ABL and FT; (3) qualitative measurements: method based on Rayleigh distillation and mixing processes, methods of ground-based remote sensing and airborne tracer-tracer relationship/ratio method.
Highlights
As lowest part of the atmosphere, ABL is formed by aerodynamic drags due to surface frictional resistance which is largely determined by the properties of the underlying surface
This review focused on the methods for observing the exchange, quantitative measurement will be introduced in Part 2 while qualitative measurement in
A possible approach to make a quantitative assessment of the total exchange is to investigate the height of inversion layer on fair weather, which reflects the dynamic balance between entrainment and subsidence
Summary
As lowest part of the atmosphere, ABL is formed by aerodynamic drags due to surface frictional resistance which is largely determined by the properties of the underlying surface. ABL usually responds to changes in surface radiative forcing in an hour or less. In this layer physical quantities such as flow velocity, temperature, moisture and so forth, display rapid fluctuations (turbulence) and vertical mixing is strong. The diurnal variation of boundary layer above the ocean is different from that above the land surface and we named the ABL above the ocean as marine boundary layer (MBL) customarily. Atmosphere 2018, 9, 460 variation of ABL height is often over 1000 m because of the large diurnal change of surface temperature. The temperature above the sea surface generally has fewer effects on diurnal variation which leads to a less diurnal change of ABL height with only a few hundred meters [3]. In Part 4, all of the methods will be concluded
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