Premium
Investigating impacts of anomalous land‐surface conditions on Australian climate with an advanced land‐surface model coupled with the BMRC GCM
Author(s) -
Yang Z.L.
Publication year - 1995
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.3370150203
Subject(s) - albedo (alchemy) , environmental science , water content , climatology , gcm transcription factors , vegetation (pathology) , moisture , general circulation model , hydrology (agriculture) , atmospheric sciences , climate change , meteorology , geography , geology , medicine , art , oceanography , geotechnical engineering , pathology , performance art , art history
A new and complex land‐surface model, the bare essentials of surface transfer (BEST), has been incorporated into the Australian Bureau of Meteorology Research Centre (BMRC) atmospheric general circulation model (GCM). A series of experiments with anomalous land‐surface conditions using the BEST‐GCM were conducted. Three sets of conditions were used for the winter, two of which were related to the soil moisture conditions. The soil over the entire Australian continent was saturated (hereafter WET) and dried (hereafter DRY) on the first time step of 4 July, and then allowed to evolve normally. In another experiment, values of all the 15 BEST parameters over the continent were set to those at a point in the Great Desert and kept unaltered throughout the integration period (hereafter DESERT). Two additional WET and DRY experiments were carried out for the summer, from 6 January for 60 days. The results of these experiments differ significantly from those conducted with bucket‐type land‐surface parameterization schemes in that:(i) WET or DRY anomalies evolve differently in specific regions. The geographical distributions of responses are more disorganized, possibly because of the inclusion of vegetation, which may enhance the regional features and the non‐linear treatment of soil moisture content and surface wetness. (ii) Magnitude of responses are larger because of the greater number of feedback mechanisms. For example, when the feedback of soil moisture and surface albedo is allowed, the increase of soil moisture leads to an increase of evaporation. The increase of soil moisture results in a decrease in albedo which in turn leads to an increase of absorbed solar radiation available for evaporation. (iii) Time‐scales of adjustment are different for DRY and WET anomalies. WET anomalies persist much longer, have stronger responses and are more organized than DRY anomalies. (iv) The summer WET or DRY anomalies have larger responses than the corresponding winter anomalies.These results are physically interpreted and their implication in seasonal precipitation forecasting is discussed.