黑潮和北大西洋海温异常在2008年1月我国南方雪灾中的可能作用的数值模拟

根据NCEP/NCAR再分析资料、NOAA扩展重建海表温度资料,利用中国科学院大气物理研究所全球大气环流谱模式（IAP-T42L9）模拟了大气环流对黑潮区、北大西洋海温异常偏暖的响应特征,并探讨了黑潮区、北大西洋海温异常在2008年1月我国南方雪灾中的作用。通过模拟场与观测场的比较表明,在考虑黑潮区和北大西洋海温异常偏暖的情况下,模式比较成功地模拟出了2008年1月我国南方发生低温、雨雪、冰冻天气的各种主要环流特征。黑潮区海温升高导致东亚沿海位势高度增加,西太平洋副热带高压偏北。它一方面不利于冷空气向下游输送,导致冷空气在我国长江流域及其以南地区堆积;另一方面加强了海洋的暖湿气流及向我国长江流域及其以南地区的水汽输送,为我国南方雨雪天气形成提供了充沛的水汽条件,有利于我国南方低温、雨雪、冰冻天气的持续。北大西洋海温异常偏暖对中高纬地区中西伯利亚阻塞高压的形成有重要作用。受其影响,我国除受东路冷空气活动的影响外,中纬度还不断有西路冷空气随着西风带槽脊东移影响我国东部地区。它是导致我国南方低温、雨雪、冰冻天气持续的另一个重要原因。     

2050年前长江流域地表水资源变化趋势

 利用ECHAM5/MPI-OM气候模式预估2001-2050年长江流域不同排放情景（SRES-A2,A1B,B1）下径流深的变化,分析了长江流域地表水资源量的时空变化特征。结果表明：3种排放情景下长江流域多年平均地表水资源量相差不大,但不同排放情景下年际变化特征较为复杂,且变化趋势有所不同。其中,A2高排放情景下地表水资源量呈缓慢减小的趋势,A1B中等排放情景下变化趋势不明显,B1低排放情景下呈相对最为显著的增加趋势。地表水资源量年代际变化波动幅度也较大,2001-2030年3种情景下地表水资源量总体呈现下降特征,但从2030年起,则均表现出不同程度的增加,最高增幅达7.47%,其中尤以夏季和冬季增加显著。模式预估长江流域未来水资源量仍保持目前水平,水资源空间分布不均匀特征仍较为突出。     

针对IPCC评估报告中海洋碳循环的疑问——δ13C收支平衡法的验证

通过对比IPCC历次评估报告中全球碳循环的收支发现,尽管评估报告在估算各主要碳库及其间的通量时差别不大,但表层至中深层海水间溶解无机碳通量却存在巨大差异。利用δ¹³C的收支平衡检验了这一通量的适用范围,结果表明：IPCC 1996年和2007年评估报告对此通量估计过大,而1990年和2001年评估报告估计偏小。     

成都市2009年小麦条锈病特重发生的气象特征

本文从小麦条锈病浸染、繁殖、流行的气象特征角度,分析了2009年成都市在小麦条锈病生物环境存在的背景下,小麦条锈病特重发生的原因：秋季温适湿重、冬季温暖露重、春季暖和多雨。初步总结出条锈病爆发流行的定量指标：在条锈病流行期内日平均气温≥10℃时,雨日（≥0．5mm）达到10天有利于爆发,该结论可为成都市小麦条锈病的预报和防治提供科学的参考。     

1961—2006年云南可利用降水量演变特征

利用云南122个测站1961—2006年逐月降水量、气温观测资料,依据高桥浩一郎的陆面实际蒸散发经验公式,计算了云南可利用降水量,分析了全球气候变暖背景下云南可利用降水量的变化特征,获得了一些有意义的结果:1)近50年来云南可利用降水量在春季增加,而其余季节减少,特别是夏季可利用降水量明显减少,导致云南年可利用降水量明显减少。2)云南可利用降水量除冬季年代际变化不明显,年际变化明显外,其余季节及年可利用降水量都存在明显的年代际及年际变化。3)从区域趋势变化看,云南大部可利用降水量在冬、春季以增加为主;夏季以减少为主;秋季东部减少,西部增加;全年可利用降水量东部、南部以减少为主,其余地区以增加为主。4)年可利用降水量在全球气候偏暖年以偏少为主,而在偏冷年则以偏多为主。     

Winter season stratospheric circulation in the SAMIL/LASG general circulation model

In this paper, we examine the performance of the 26-level version of the SAMIL/LASG GCM (R42/L26) in simulating the seasonal cycle and perpetual winter mean stratospheric circulation as well as its variability by comparing them with the NCEP/NCAR reanalysis. The results show that the model is capable of reproducing many key features of the climatology and seasonal variation of the stratospheric circulation despite that the model’s mean polar vortex is stronger and more zonally symmetric compared to the obse...     

Hawking radiation and entropy in de Sitter spacetime

Using the analytic extension method, we study Hawking radiation of an (n+4)-dimensional Schwarzschild-de Sitter black hole. Under the condition that the total energy is conserved, taking the reaction of the radiation of particles to the spacetime into consideration and considering the relation between the black hole event horizon and cosmological horizon, we obtain the radiation spectrum of de Sitter spacetime. This radiation spectrum is no longer a strictly pure thermal spectrum. It is related to the change of the Bekenstein-Hawking (B-H) entropy corresponding the black hole event horizon and cosmological horizon. The result satisfies the unitary principle. At the same time, we also testify that the entropy of de Sitter spacetime is the sum of the entropy of black hole event horizon and the one of cosmological horizon.     

钙质砂中模型桩的试验研究

根据钙质砂中桩基工程的现状,针对取自南沙群岛永暑礁的钙质砂,设计一个室内模型试验装置来研究钙质砂中钢管桩的承载和变形性能以及影响因素,并进行了石英砂中的对比试验。试验结果表明,钢管桩在钙质砂和石英砂中的表现有着显著差异。钙质砂中钢管桩承载能力很低,仅为石英砂的66%～70%,钙质砂中桩身轴力衰减速率缓慢,桩侧摩阻力远远小于石英砂的,仅为石英砂的20%～27%,并具有深度效应,开口钢管桩和闭口钢管桩的桩侧摩阻力相差不大。同时表明,钙质砂中桩侧摩阻力对相对密度的变化没有石英砂敏感,受相对密度影响很小。由颗粒破碎引起的桩周水平有效应力的大幅降低是造成钙质砂中钢管桩桩侧摩阻力低的主要原因。     

A new ice sheet model validated by remote sensing of the Greenland ice sheet

Accurate prediction of future sea level rise requires models that accurately reproduce and explain the recent observed dramatic ice sheet behaviours. This study presents a new multi-phase, multiple-rheology, scalable and extensible geofluid model of the Greenland ice sheet that shows the credential of successfully reproducing the mass loss rate derived from the Gravity Recovery and Climate Experiment (GRACE), and the microwave remote sensed surface melt area over the past decade. Model simulated early 21st century surface ice flow compares satisfactorily with InSAR measurements. Accurate simulation of the three metrics simultaneously cannot be explained by fortunate model tuning and give us confidence in using this modelling system for projection of the future fate of Greenland Ice Sheet (GrIS). Based on this fully adaptable three dimensional, thermo-mechanically coupled prognostic ice model, we examined the flow sensitivity to granular basal sliding, and further identified that this leads to a positive feedback contributing to enhanced mass loss in a future warming climate. The rheological properties of ice depend sensitively on its temperature, thus we further verified modelâ?s temperature solver against in situ observations. Driven by the NCEP/NCAR reanalysis atmospheric parameters, the ice model simulated GrIS mass loss rate compares favourably with that derived from the GRACE measurements, or about ?147 km³/yr over the 2002–2008 period. Increase of the summer maximum melt area extent (SME) is indicative of expansion of the ablation zone. The modeled SME from year 1979 to 2006 compares well with the cross-polarized gradient ratio method (XPGR) observed melt area in terms of annual variabilities. A high correlation of 0.88 is found between the two time series. In the 30-year model simulation series, the surface melt exhibited large inter-annual and decadal variability, years 2002, 2005 and 2007 being three significant recent melt episodes.     

影响副高活动的热力强迫作用——动力学解析模型

采用最优化搜索方法,对影响副高活动的东亚季风区位势场和季风雨带降水场进行了函数拟合,并用拟合出的函数作为基函数和热力强迫因子代入正压涡度方程,对涡度方程解的性质进行了讨论。分析和模拟结果表明:中心位于我国华北一带东亚季风雨带凝结潜热释放易导致副高的西伸和北抬;而中心位于赤道附近的南海季风槽降水热力作用可导致副高出现东退和西伸两种可能。