Performance of RegCM4 over Major River Basins in China

A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions at a grid spacing of 25 km. The Community Land Model（CLM） is used to describe land surface processes, with updates in the surface parameters,including the land cover and surface emissivity. The simulation is compared against observations to evaluate the model performance in reproducing the present day climatology and interannual variability over the 10 main river basins in China,with focus on surface air temperature and precipitation. Temperature and precipitation from the ERA-Interim reanalysis are also considered in the model assessment. Results show that the model reproduces the present day climatology over China and its main river basins, with better performances in June–July–August compared to December–January–February（DJF）.In DJF, we find a warm bias at high latitudes, underestimated precipitation in the south, and overestimated precipitation in the north. The model in general captures the observed interannual variability, with greater skill for temperature. We also find an underestimation of heavy precipitation events in eastern China, and an underestimation of consecutive dry days in northern China and the Tibetan Plateau. Similar biases for both mean climatology and extremes are found in the ERA-Interim reanalysis, indicating the difficulties for climate models in simulating extreme monsoon climate events over East Asia.

Salt lakes in China:Challenges for reconstructing ecological and climate variations

1 Introduction Studies on lakes have become an important concern for many scientists since it is well known that lakes can monitor detailed information about ecological,hydrological and sedimentary cycles which can be

Atacamite and Nantokite in Kaerqueka Copper Deposit of Qimantag Area:Evidence for Cenozoic Climate Evolution of the Qaidam Basin

Using a mineralogy method to reflect climate evolution is a new approach to research Cenozoic environmental progression of the Qaidam Basin. In this paper, we present the chemical composition and crystallographic parameter of atacamite, nantokite, and tenorite in cryptocrystalline aggregates from the Kaerqueka copper deposit of Qimantag metallogenic belt by means of electron microprobe and in-situ X-ray diffraction analyses. Atacamite and nantokite occur in an intimate intergrowth as the secondary precipitation of chalcopyrite and bornite filling in the interstitial space of andradite in the Kaerqueka copper deposit, with an average composition of Cl： 12.38 wt.%, Cu： 63.76 wt.%, O： 21.46 wt.%. X-ray microdiffraction shows that the intergrowth contains nantokite with a cubic unit cell a=5.403（2） ？ and atacamite with an orthorhombic unit cell a=6.030（3）, b=6.883（2）, c=9.114（1） ？. XRD quantitative calculation shows that the nanometric aggregate contains 36.07 wt.% tenorite, 18.41 wt.% atacamite, and 45.52 wt.% nantokite. The presence of nantokite and atacamite requires saline solutions for their formation and hyper-arid climate conditions for their preservation. Combined with the data of salt lakes and the pollen sequence of western China, we suggest that during the uplift of the Tibetan Plateau and the retreat of the Paratethys, saline water was forced to the surface through a basal fracture zone. In the hyper-arid climate of the Qaidam Basin, the recharge of groundwater by direct precipitation is negligible, and groundwater is derived from inflow from the salt lakes. Thus, atacamite is preserved. In addition, spertiniite in the edge and fractures of atacamite and nantokite may represent wetter climate after the formation of atacamite and nantokite.

Palaeogeographic reconstruction of Minchin palaeolake system,South America: The influence of astronomical forcing

Current palaeoclimatic reconstructions for the R＆#237;o de la Plata region during the latest Pleistocene （30,000 e10,000 yr BP） propose dry conditions, with rainfall at the Last Glacial Maximum amounting to one-third of today＇s precipitation. Despite the consequential low primary productivity inferred, an impressive megafauna existed in the area at that time. Here we explore the influence of the flooding from a huge extinct system of water bodies in the Andean Altiplano as a likely source for wet regimes that might have increased the primary productivity and, hence, the vast number of megaherbivores. The system was reconstructed using specifically combined software resources, including Insola, Global Mapper v13, Surfer and Matlab. Changes in water volume and area covered were related to climatic change, assessed through a model of astronomical forcing that describes the changes in insolation at the top of the at-mosphere in the last 50,000 yr BP. The model was validated by comparing its results with several proxies （CH4, CO2, D, 18O） from dated cores taken from the ice covering Antarctic lakes Vostok and EPICA Dome C. It is concluded that the Altiplano Lake system drained towards the southeast in the rainy seasons and that it must have been a major source of water for the Paran＆#225;-Plata Basin, consequently enhancing primary productivity within it.