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Available from: Bert Holtslag, Jul 08, 2015
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    • "Turbulent transport between the surface and the atmosphere ceases, sometimes referred to as 'crashing' (Derbyshire 1999). Van de Wiel et al. (2002) identifies this flow regime as a 'radiative regime'. Both of these studies elucidate the flow regimes in relation to dynamic stability, as related to surface radiative forcing, the horizontal pressure gradient, thermal properties of the surface and surface roughness. "
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    ABSTRACT: The stable nocturnal boundary layer is commonly viewed or modelled as a balance between the temperature tendency (cooling) and vertical heat-flux divergence. Sometimes the radiative-flux divergence is also included. This perspective has dictated the design of field experiments for investigating stable nocturnal boundary layers. Tower-based micrometeorological data from three field campaigns are analysed to evaluate the vertically integrated sensible-heat budget for nocturnal stable conditions. Our analysis indicates frequent occurrence of large imbalance between the temperature tendency and vertical heat-flux divergence terms. The values of the radiative-flux divergence are generally too small and sometimes of the wrong sign to explain the residual. An analysis of random flux errors and uncertainties in the tendency term indicate that such errors cannot explain large imbalances, suggesting the importance of advection of temperature or possibly the divergence of mesoscale fluxes. The implied role of advection is consistent with circumstantial evidence. Even weak surface heterogeneity can create significant horizontal gradients in stable boundary layers. However, it is shown that existing field data and observational strategy do not allow adequate evaluation of advection and mesoscale flux divergence terms.
    Quarterly Journal of the Royal Meteorological Society 01/2006; 132(615). DOI:10.1256/qj.05.50 · 5.13 Impact Factor
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    • "Ook op andere locaties in Nederland werd dit gedrag in die nacht waargenomen. Het getoonde gedrag kan grotendeels worden verklaard met een relatief simpel conceptueel model dat door een van de promovendi van de leerstoelgroep ontwikkeld is (van de Wiel et al, 2002). "
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    ABSTRACT: The techniques of nonlinear analysis are used to examine the behavior of the stable nocturnal boundary layer (SNBL) when it is subjected to changes in incoming radiation or in surface characteristics. A single-column model and nonlinear bifurcation techniques are used to demonstrate that any atmospheric forcing, such as weak radiative forcing from greenhouse gases or cloud cover, can trigger a potentially significant positive feedback. Multiple solutions occur in some parameter spaces. This analysis shows that any forcing that decreases the stability, whether by increasing greenhouse gases or surface heat capacity, can cause large increases in surface temperature as the SNBL shifts from a weak turbulent regime, which allows the surface to cool, to a turbulent regime, which mixes warm air from aloft. Positive feedback may be a key factor in interpreting the long-term observed nocturnal warming trend in the SNBL.
    01/2007; 34(12). DOI:10.1029/2007GL029505