Abstract
Abstract. We present the first measurement of the sensible heat flux (H) profile in the convective boundary layer (CBL) derived from the covariance of collocated vertical-pointing temperature rotational Raman lidar and Doppler wind lidar measurements. The uncertainties of the H measurements due to instrumental noise and limited sampling are also derived and discussed. Simultaneous measurements of the latent heat flux profile (L) and other turbulent variables were obtained with the combination of water-vapor differential absorption lidar (WVDIAL) and Doppler lidar. The case study uses a measurement example from the HOPE (HD(CP)2 Observational Prototype Experiment) campaign, which took place in western Germany in 2013 and presents a cloud-free well-developed quasi-stationary CBL. The mean boundary layer height zi was at 1230 m above ground level. The results show – as expected – positive values of H in the middle of the CBL. A maximum of (182±32) W m−2, with the second number for the noise uncertainty, is found at 0.5 zi. At about 0.7 zi, H changes sign to negative values above. The entrainment flux was (-62±27) W m−2. The mean sensible heat flux divergence in the observed part of the CBL above 0.3 zi was −0.28 W m−3, which corresponds to a warming of 0.83 K h−1. The L profile shows a slight positive mean flux divergence of 0.12 W m−3 and an entrainment flux of (214±36) W m−2. The combination of H and L profiles in combination with variance and other turbulent parameters is very valuable for the evaluation of large-eddy simulation (LES) results and the further improvement and validation of turbulence parameterization schemes.
Highlights
The energy reaching the earth surface in form of solar radiation during the daytime is partly reflected as outgoing radiation, partly conducted into the ground and partly transported into the atmosphere by turbulent eddies of various scales forming the convective boundary layer (CBL) during the daytime (LeMone, 2002)
We have presented the first measurements of sensible heat flux profiles H (z) in the daytime convective boundary layer made with ground-based remote sensing
The temperature fluctuations were obtained from UV rotational Raman lidar measurements, while the vertical wind measurements were made with a coherent Doppler lidar
Summary
The energy reaching the earth surface in form of solar radiation during the daytime is partly reflected as outgoing radiation, partly conducted into the ground and partly transported into the atmosphere by turbulent eddies of various scales forming the convective boundary layer (CBL) during the daytime (LeMone, 2002). The latter energy flux partitions into sensible heat flux H and latent heat flux L. Weckwerth et al (1996) found strong variability in the moisture structure in the CBL due to the presence of horizontal convective rolls.
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