Print Email Facebook Twitter Should we use a simple or complex model for moisture recycling and atmospheric moisture tracking? Title Should we use a simple or complex model for moisture recycling and atmospheric moisture tracking? Author Van der Ent, R.J. Tuinenburg, O.A. Knoche, H.R. Kunstmann, H. Savenije, H.H.G. Faculty Civil Engineering and Geosciences Department Water Management Date 2013-05-29 Abstract This paper compares three state-of-the-art atmospheric moisture tracking models. Such models are typically used to study the water component of coupled land and atmosphere models, in particular quantifying moisture recycling and the source-sink relations between evaporation and precipitation. However, there are several atmospheric moisture tracking methods being used in the literature, and depending on the level of aggregation, the assumptions made and the level of detail, the performance of these methods may differ substantially. In this paper, we compare three methods. The RCM-tag method uses highly accurate 3-D water tracking (including phase transitions) directly within a regional climate model (online), while the other two methods (WAM and 3D-T) use a posteriori (offline) water vapour tracking. The original version of WAM makes use of the well-mixed assumption, while 3D-T is a multi-layer model. The a posteriori models are faster and more flexible, but less accurate than online moisture tracking with RCM-tag. In order to evaluate the accuracy of the a posteriori models, we tagged evaporated water from Lake Volta in West Africa and traced it to where it precipitates. It is found that the strong wind shear in West Africa is the main cause of errors in the a posteriori models. The number of vertical layers and the initial release height of tagged water in the model are found to have the most significant influences on the results. With this knowledge small improvements were made to the a posteriori models. It appeared that expanding WAM to a 2 layer model, or a lower release height in 3D-T, led to significantly better results. Finally, we introduced a simple metric to assess wind shear globally and give recommendations about when to use which model. The "best" method, however, very much depends on the spatial extent of the research question as well as the available computational power. To reference this document use: http://resolver.tudelft.nl/uuid:d01d7a61-4369-4432-8353-923e491831f3 DOI https://doi.org/10.5194/hessd-10-6723-2013 Publisher European Geosciences Union ISSN 1812-2108 Source Hydrology and Earth System Sciences Discussions, 10 (5), 2013 Part of collection Institutional Repository Document type journal article Rights © 2013 The Author(s)CC Attribution 3.0 License Files PDF vanderEnt_2013.pdf 1.33 MB Close viewer /islandora/object/uuid:d01d7a61-4369-4432-8353-923e491831f3/datastream/OBJ/view