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The climatological features of the winter snow depth over the Tibetan Plateau and the summer precipitation in China are diagnosed using datasets obtained from 78 snow observation stations and 160 rainfall stations during 1957 to 1998. The climatic effects of the snow anomaly over the Tibetan Plateau on the regional summer monsoon climate in China are diagnosed and numerically simulated by use of a regional climate model (RegCM2). The singular value decomposition technique is adopted to diagnose the relationships between the previous winter and spring plateau snow depth anomalies and the spring and summer regional precipitation in China. It is found that the snow depth anomaly, especially in winter, is one of the factors influencing precipitation in China; however, it is perhaps not the only one, and even not the most important one. Nevertheless, it is proved that the winter snow anomaly over the Tibetan Plateau is relatively more important than that in spring for the regional precipitation in China. Results of numerical simulations show that the snow anomaly over the plateau has effects that are evident on China's summer monsoon climate. The increase of both snow cover and snow depth can delay the onset and weaken the intensity of the summer monsoon obviously, resulting in a decrease in precipitation in southern China and an increase in the Yangtze and Huaihe River basins. The influence of the winter snow depth is more substantial than that of both the winter snow cover and the spring snow depth. The mechanism of how the plateau snow anomaly influences the regional monsoon climate is briefly analysed. It is found that snow anomalies over the Tibetan Plateau change the soil moisture and the surface temperature through the snowmelt process at first, and subsequently alter heat, moisture and radiation fluxes from the surface to the atmosphere. Abnormal circulation conditions induced by changes of surface fluxes may affect the underlying surface properties in turn. Such a long-term interaction between the wetland and the atmosphere is the key process resulting in later climatic changes.

We deal with the classical limit of the Schrödinger-Poisson system to the Vlasov-Poisson equations as the Planck constant goes to zero. This limit is also frequently called the "semiclassical limit." The coupled Schrödinger-Poisson system for the wave functions {ψ j (t, x)} is transformed to the Wigner-Poisson equations for a "phase space function" f (t, x, ξ ). For the case of the so-called completely mixed state, i.e., j = 1, 2, . . . , ∞, under additional assumptions on the potential, this classical limit was solved in 1993 by P. The so-called pure state case, where only one or a finite number of wave functions {ψ j (t, x)} are considered, has been open up to now.We prove here for general initial data (the pure-state as well as the mixedstate case) of the wave functions in one space dimension that the Wigner measure f (t, x, ξ ), which is a weak limit of f (t, x, ξ ) as tends to 0, satisfies the classical one-dimensional Vlasov-Poisson equations. As a by-product, we have improved the decay assumption on the initial data of one-dimensional Vlasov-Poisson equations in [38] for the existence of global weak solutions with measures as initial data.The equations we regard are widely used in quantum/classical transport and semiconductor theory as a nonlinear one-particle ("mean field") approximation of the linear N -electron Schrödinger/Hamilton equation.

Abstract. Using a succession of 24 h Weather Research andForecasting model (WRF) simulations, we investigate the sensitivity to initial soil moisture of a short-range hightemperature weather event that occurred in late July 2003 in East China. The initial soil moisture (SMOIS) in the Noah land surface scheme is adjusted (relative to the control run, CTL) for four groups of simulations: DRY25 (−25 %), DRY50 (−50 %), WET25 (+25 %) and WET50 (+50 %). Ten 24 h integrations are performed in each group.We focus on 2 m surface air temperature (SAT) greater than 35 • C (the threshold of "high-temperature" events in China) at 06:00 UTC (roughly 14:00 LT in the study domain) to analyse the occurrence of the high-temperature event. The 10-day mean results show that the 06:00 UTC SAT (SAT06) is sensitive to the SMOIS change; specifically, SAT06 exhibits an apparent increase with the SMOIS decrease (e.g. compared with CTL, DRY25 generally results in a 1 • C SAT06 increase over the land surface of East China), areas with 35 • C or higher SAT06 are the most affected, and the simulations are more sensitive to the SMOIS decrease than to the SMOIS increase, which suggests that hot weather can be amplified under low soil moisture conditions. Regarding the mechanism underlying the extremely high SAT06, sensible heat flux has been shown to directly heat the lower atmosphere, and latent heat flux has been found to be more sensitive to the SMOIS change, resulting in an overall increase in surface net radiation due to the increased greenhouse effect (e.g. with the SMOIS increase from DRY25 to CTL, the 10-day mean net radiation increases by 5 W m −2 ). Additionally, due to the unique and dynamic nature of the western Pacific subtropical high, negative feedback occurs between the regional atmospheric circulation and the air temperature in the lower atmosphere while positive feedback occurs in the midtroposphere.Using a method based on an analogous temperature relationship, a detailed analysis of the physical processes shows that for the SAT change, the SMOIS change affects diabatic processes (e.g. surface fluxes) more strongly than the adiabatic process of subsidence in the western Pacific subtropical high in the five groups of simulations. Interestingly, although diabatic processes dominate subsidence during the daytime and night-time separately, they do not necessarily dominate during the 24 h periods (e.g. they are dominant in the WET and CTL simulations only). Further, as the SMOIS decreases, the SAT06 increases, which is largely due to the reduced cooling effect of the diabatic processes, rather than the warming effect of subsidence.Unlike previous studies on heatwave events at climate timescales, this paper presents the sensitivity of simulated short-term hot weather to initial soil moisture and emphasises the importance of appropriate soil moisture initialization when simulating hot weather.

The simulations of a heat wave occurring in southern Yangtze-Huaihe valley and southern China during late July, 2003 were conducted to examine the sensitivity of simulated surface air temperature (SAT) to different land surface schemes (LSSs) using the Weather Research and Forecasting Model (WRF) Version 2.2 in the short-range mode for 24-h integrations. Initial and boundary conditions employed a National Centers for Environmental Prediction (NCEP) analysis. The results showed that, overall, simulated high-temperature weather is sensitive to different LSSs. Large differences in simulated SAT intensity, threat score, and simulated error under different schemes are identified clearly. In addition, some systematic differences are also induced by the LSSs. In terms of threat score from the three LSSs, SLAB is the best, and RUC is better than NOAH. SLAB gives the lowest absolute error for area-averaged SAT, and tends to depict the western Pacific subtropical high with the easternmost position at low levels. The LSSs modify the simulated SAT, primarily via the transfer of sensible heat from the land surface to the atmosphere. The physical mechanism of the positive feedback between atmospheric circulation and the SAT is unimportant, with "negative" feedback over most of the simulated areas. This study emphasizes the importance of improving LSSs in SAT forecasting by numerical models.WRF, land surface scheme, high-temperature weather, sensitivity experiment. Citation:Zeng X M, Wu Z H, Xiong S Y, et al. Sensitivity of simulated short-range high-temperature weather to land surface schemes by WRF.

We designed simulations for the high-temperature event that occurred on 23 July 2003 in East China using a series of forecast lead times, from short-range to medium-range, and four land surface schemes (LSSs) (i.e., SLAB, NOAH, RUC, and PX) in the Weather Research and Forecasting Model (WRF), Version 3. The sensitivities of short and medium-range simulations to the LSSs systematically varied with the lead times. In general, the model reproduced short-range, high-temperature distributions. The simulated weather was sensitive to the LSSs, and the LSS-induced sensitivity was higher in the medium range than in the short-range. Furthermore, the LSS performances were complex, i.e., the PX errors apparently increased in the medium range (longer than 6 days), RUC produced the maximum errors, and SLAB and NOAH had approximately equivalent errors that slightly increased. Additional sensitivity simulations revealed that the WRF modeling system assigns relatively low initial soil moisture for RUC and that soil moisture initialization plays an important role that is comparable to the LSS choice in the simulations. LSS-induced negative feedback between surface air temperature (SAT) and atmospheric circulation in the lower atmosphere was found in the medium range. These sensitivities were mainly caused by the LSS-induced differences in surface sensible heat flux and by errors associated with the lead times. Using the SAT equation, further diagnostic analyses revealed LSS deficiencies in simulating surface fluxes and physical processes that modify the SAT and indicated the main reasons for these deficiencies. These results have implications for model improvement and application.