Boundary-Layer Meteorology

, Volume 135, Issue 2, pp 313–331

Frequency of Boundary-Layer-Top Fluctuations in Convective and Stable Conditions Using Laser Remote Sensing

Authors

    • School of Physics & Centre for Climate and Air Pollution Studies, Environmental Change InstituteNational University of Ireland, Galway
  • Renaud Matthey
    • Laboratory for Time and Frequency, Institute of PhysicsUniversity of Neuchâtel
  • Valentin Mitev
    • CSEM – Centre Suisse d’électronique et de Microtechnique
  • Hans Richner
    • Institute for Atmospheric and Climate ScienceETH Hönggerberg HPP
Article

DOI: 10.1007/s10546-010-9474-3

Cite this article as:
Martucci, G., Matthey, R., Mitev, V. et al. Boundary-Layer Meteorol (2010) 135: 313. doi:10.1007/s10546-010-9474-3

Abstract

The planetary boundary-layer (PBL) height is determined with high temporal and altitude resolution from lidar backscatter profiles. Then, the frequencies of daytime thermal updrafts and downdrafts and of nighttime gravity waves are obtained applying a fast Fourier transform on the temporal fluctuation of the PBL height. The principal frequency components of each spectrum are related to the dominant processes occurring at the daytime and nighttime PBL top. Two groups of cases are selected for the study: one group combines daytime cases, measured in weak horizontal wind conditions and dominated by convection. The cases show higher updraft and downdraft frequencies for the shallow, convective boundary layer and lower frequencies for a deep PBL. For cases characterized by strong horizontal winds, the frequencies directly depend on the wind speed. The temporal variation of the PBL height is determined also in the likely presence of lee waves. For nighttime cases, the main frequency components in the spectra do not show a real correlation with the nocturnal PBL height. Altitude fluctuations of the top of the nocturnal boundary layer are observed even though the boundary layer is statically stable. These oscillations are associated with the wind shear effect and with buoyancy waves at the PBL top.

Keywords

ConvectionLidarPlanetary boundary-layer heightThermalsTop oscillation

Abbreviations

PBL

Planetary boundary layer

CBL

Convective boundary layer

EARLINET

European Aerosol Research Lidar Network

EC

European Commission

EZ

Entrainment zone

FFT

Fast Fourier transform

FOV

Field of View

GS

Gradient signal

KH

Kelvin–Helmholtz

NBL

Nocturnal boundary layer

RCS

Range-corrected signal

SNR

Signal-to-noise ratio

UTC

Universal Coordinated Time

Var

Variance

Copyright information

© Springer Science+Business Media B.V. 2010