Analyzing the turbulent planetary boundary layer by remote sensing systems: the Doppler wind lidar, aerosol elastic lidar and microwave radiometer
<p>The planetary boundary layer (PBL) is the lowermost region of troposphere and is endowed with turbulent characteristics, which can have mechanical and/or thermodynamic origins. This behavior gives this layer great importance, mainly in studies about pollutant dispersion and weather forecast...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/1263/2019/acp-19-1263-2019.pdf |
| Summary: | <p>The planetary boundary layer (PBL) is the lowermost region of troposphere
and is endowed with turbulent characteristics, which can have mechanical and/or
thermodynamic origins. This behavior gives this layer great importance,
mainly in studies about pollutant dispersion and weather forecasting.
However, the instruments usually applied in studies of turbulence in the
PBL have limitations in spatial resolution (anemometer towers) or temporal
resolution (instrumentation aboard an aircraft). Ground-based remote sensing,
both active and passive, offers an alternative for studying the PBL. In
this study we show the capabilities of combining different remote sensing
systems (microwave radiometer – MWR, Doppler lidar – DL – and elastic
lidar – EL) for retrieving a detailed picture on the PBL turbulent
features. The statistical moments of the high frequency distributions of the
vertical wind velocity, derived from DL, and of the backscattered
coefficient, derived from EL, are corrected by two methodologies, namely
first lag correction and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">2</mn><mo>/</mo><mn mathvariant="normal">3</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="68a597ee0fc95fc948658c971f4eed6e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-1263-2019-ie00001.svg" width="28pt" height="14pt" src="acp-19-1263-2019-ie00001.png"/></svg:svg></span></span> law correction. The corrected profiles, obtained from DL
data, present small differences when compared with the uncorrected
profiles, showing the low influence of noise and the viability of the
proposed methodology. Concerning EL, in addition to analyzing the influence
of noise, we explore the use of different wavelengths that usually include
EL systems operated in extended networks, like the European Aerosol Research Lidar Network (EARLINET), Latin American Lidar Network (LALINET), NASA Micro-Pulse Lidar Network
(MPLNET) or Skyradiometer Network (SKYNET). In this way we want to show the feasibility of extending the
capability of existing monitoring networks without strong investments or
changes in their measurements protocols. Two case studies were analyzed in
detail, one corresponding to a well-defined PBL and another
corresponding to a situation with presence of a Saharan dust lofted aerosol
layer and clouds. In both cases we discuss results provided by the different
instruments showing their complementarity and the precautions to be applied in
the data interpretation. Our study shows that the use of EL at 532 nm
requires a careful correction of the signal using the first lag time
correction in order to get reliable turbulence information on the PBL.</p> |
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| ISSN: | 1680-7316 1680-7324 |