On the role of the planetary boundary layer depth in the climate system
The planetary boundary layer (PBL) is a part of the Earth's atmosphere where turbulent fluxes dominate vertical mixing and constitute an important part of the energy balance. The PBL depth, <i>h</i>, is recognized as an important parameter, which controls some features of the Earth&...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2010-05-01
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| Series: | Advances in Science and Research |
| Online Access: | http://www.adv-sci-res.net/4/63/2010/asr-4-63-2010.pdf |
| Summary: | The planetary boundary layer (PBL) is a part of the
Earth's atmosphere where turbulent fluxes dominate vertical mixing and
constitute an important part of the energy balance. The PBL depth, <i>h</i>, is
recognized as an important parameter, which controls some features of the
Earth's climate and the atmospheric chemical composition. It is also known
that <i>h</i> varies by two orders of magnitude on diurnal and seasonal time
scales. This brief note highlights effects of this variability on the
atmospheric near-surface climate and chemical composition. We interpret heat
capacity parameter of a Budyko-type energy balance model in terms of
quasi-equilibrium <i>h</i>. The analysis shows that it is the shallowest,
stably-stratified PBL with the smallest <i>h</i> that should be of particular
concern for climate modelling. The reciprocal dependence between the PBL
depth and temperature (concentrations) is discussed. In particular, the
analysis suggests that the climate characteristics during stably stratified
PBL episodes should be significantly more sensitive to perturbations of the
Earth's energy balance as well as emission rates. On this platform, <i>h</i> from
ERA-40 reanalysis data, the CHAMP satellite product and the DATABASE64 data
were compared. DATABASE64 was used to assess the Troen-Mahrt method to
determine <i>h</i> through available meteorological profile observations. As it
has been found before, the shallow PBL requires better parameterization and
better retrieval algorithms. The study demonstrated that ERA-40 and CHAMP
data are biased toward deeper <i>h</i> in the shallow polar PBL. This, coupled
with the scarcity of in-situ observations might mislead the attribution of
the origins of the Arctic climate change mechanisms. |
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| ISSN: | 1992-0628 1992-0636 |