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. (2019). Importance of the advection scheme for the simulation of water isotopes over Antarctica by atmospheric general circulation models: A case study for present-day and Last Glacial Maximum with LMDZ-iso (Vol. 524). Bachelor's thesis, , .
Abstract: Atmospheric general circulation models (AGCMs) are known to have a warm and isotopically enriched bias over Antarctica. We test here the hypothesis that these biases are partly consequences of a too diffusive advection. Exploiting the LMDZ-iso model, we show that a less diffusive representation of the advection, especially on the horizontal, is very important to reduce the bias in the isotopic contents of precipitation above this area. The choice of an appropriate representation of the advection is thus essential when using GCMs for paleoclimate applications based on polar water isotopes. Too much diffusive mixing along the poleward transport leads to overestimated isotopic contents in water vapor because dehydration by mixing follows a more enriched path than dehydration by Rayleigh distillation. The near-air surface temperature is also influenced, to a lesser extent, by the diffusive properties of the advection scheme directly via the advection of the air and indirectly via the radiative effects of changes in high cloud fraction and water vapor. A too diffusive horizontal advection increases the temperature and so also contributes to enrich the isotopic contents of water vapor over Antarctica through a reduction of the distillation. The temporal relationship, from Last Glacial Maximum (LGM) to present-day conditions, between the mean annual near-air surface temperature and the water isotopic contents of precipitation for a specific location can also be impacted, with significant consequences on the paleo-temperature reconstruction from observed changes in water isotopes.
Programme: 1013,1149,1176
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Ivo G. S. van Hooijdonk, Herman J. H. Clercx, Carsten Abraham, Amber M. Holdsworth, Adam H. Monahan, Etienne Vignon, Arnold F. Moene, Peter Baas, Bas J. H. van de Wiel. (2017). Near-Surface Temperature Inversion Growth Rate during the Onset of the Stable Boundary Layer (Vol. 74). Bachelor's thesis, , .
Abstract: Abstract This study aims to find the typical growth rate of the temperature inversion during the onset of the stable boundary layer around sunset. The sunset transition is a very challenging period for numerical weather prediction, since neither accepted theories for the convective boundary layer nor those for the stable boundary layer appear to be applicable. To gain more insight in this period, a systematic investigation of the temperature inversion growth rate is conducted. A statistical procedure is used to analyze almost 16 years of observations from the Cabauw observational tower, supported by observations from two additional sites (Dome C and Karlsruhe). The results show that, on average, the growth rate of the temperature inversion (normalized by the maximum inversion during the night) weakly declines with increasing wind speed. The observed growth rate is quantitatively consistent among the sites, and it appears insensitive to various other parameters. The results were also insensitive to the afternoon decay rate of the net radiation except when this decay rate was very weak. These observations are compared to numerical solutions of three models with increasing complexity: a bulk model, an idealized single-column model (SCM), and an operational-level SCM. It appears only the latter could reproduce qualitative features of the observations using a first-order closure. Moreover, replacing this closure with a prognostic TKE scheme substantially improved the quantitative performance. This suggests that idealized models assuming instantaneous equilibrium flux-profile relations may not aid in understanding this period, since history effects may qualitatively affect the dynamics.
Programme: 1013,1176
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Garrigue C., Peltier H., Ridoux V., Franklin T., Charrassin J.-B. (2010). CETA: a new cetacean observation program in East Antarctica. Paper SC/62/SH3 presented to the Scientific Committee of the International Whaling Commission, June 2010, Agadir, Morocco..
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Garrigue C., Peltier H., Ridoux V., Franklin T., Charrassin J.-B. (2010).
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Constantine R., Allen J., Beeman P., Burns D., Charrassin J.-B., Childerhouse S., Double M.C., Ensor P., Franklin T., Franklin W., Gales N., Garrigue C., Gates E., Gibbs N., Hutsel A, Jenner C., Jenner M., Kaufman G., Macie A., Mattila D.K., Oosterman A., Paton D., Robbins J., Schmitt N., Stevick P., Tagarino A., Thompson K. (2011). Comprehensive photo-identification matching of Antarctic Area V humpback whales. Paper SC/63/SH16 presented to the Scientific Committee of the International Whaling Commission, June 2011, Tromsoe, Norway.
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Garrigue C., Peltier H., Chambellant M., Ridoux V., Charrassin J.-B. (2011).
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Chambellant, M., Garrigue, C., Peltier, H., V. Ridoux, Charrassin J.-B. (2012). First photo-ID catalogue of killer whales (Orcinus orca) in East Antarctica.Paper SC/64/SM6 presented to the Scientific Committee of the International Whaling Commission, June 2012, Panama. .
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. (2014). Remote Antarctic feeding ground important for east Australian humpback whales (Vol. 161).
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. (2014). An update of the CETA project: cetacean observation program in East Antarctica 2010-2014 (Vol. SC65b/SH05).
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. (2009). Diapycnal mixing in an Arctic coastal polynya. .
Abstract: AGU fall meeting 14 – 18 December 2009, San Francisco, USA
Programme: 1015
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