Influence of Changes in Solar Radiation on Changes of Surface Temperature in China

The long-term trends of total surface solar radiation(SSR),surface diffuse radiation,and surface air temperature were analyzed in this study based on updated 48-yr data from 55 observational stations in China,and then the correlation between SSR and the diurnal temperature range(DTR) was studied.The effect of total solar radiation on surface air temperature in China was investigated on the basis of the above analyses.A strong correlation between SSR and DTR was found for the period 1961-2008 in China.The highest correlation and steepest regression line slope occurred in winter,indicating that the solar radiation effect on DTR was the largest in this season.Clouds and water vapor have strong influences on both SSR and DTR,and hence on their relationship.The largest correlations between SSR and DTR occurred in wintertime in northern China,regardless of all-day(including clear days and cloudy days) or clear-day cases.Our results also showed that radiation arriving at the surface in China decreased significantly during 1961-1989(dimming period),but began to increase during 1990-2008(brightening period),in agreement with previous global studies.The reduction of total SSR offset partially the greenhouse warming during 1961-1989.However,with the increase of SSR after 1990,this offsetting effect vanished;on the contrary,it even made a contribution to the accelerated warming.Nonetheless,the greenhouse warming still played a controlling role because of the increasing of minimum and mean surface temperatures in the whole study period of 1961-2008.We estimated that the greenhouse gases alone may have caused surface temperatures to rise by 0.31-0.46℃(10 yr) 1 during 1961-2008,which is higher than previously estimated.Analysis of the corresponding changes in total solar radiation,diffuse radiation,and total cloud cover indicated that the dimming and brightening phenomena in China were likely attributable to increases in absorptive and scattering aerosols in the atmosphere,respectively.     

2011年浙江梅汛期前后旱涝急转形势及梅雨锋结构特征分析

2011年浙江省出现了自1999年以来最典型、最强的梅雨降水集中期,连续4次强降水过程造成旱涝急转.本文利用NCEP再分析资料对2011年浙江梅汛期前后大尺度环流背景进行了分析并与历史同期进行了对比,同时又对4次强降水过程的梅雨锋结构进行了诊断分析.结果表明:(1)中高纬环流急转前后都具有很大的经向度,但由急转前的“三槽三脊”转变为“两槽一脊”,梅汛期为单阻形势,贝加尔湖阻塞高压前的西北气流为梅雨提供了冷空气条件.梅汛期印缅槽和西太平洋副热带高压较急转前明显加深、加强,偏强的印缅槽和西太平洋副热带高压有利于在副热带高压西北侧建立持久、稳定的水汽通道,西南气流与偏东气流在浙江构成准纬向切变,使得大量暖湿气流辐合上升,青藏高压北侧的偏北大风造成高层强烈辐散,这都为暴雨提供了良好的动力和水汽条件.(2)暴雨主要出现在梅雨锋前沿,梅雨锋区的上升运动与南北两支下沉气流相配合,北支携带冷空气向梅雨锋输送,南支与梅雨锋区上升气流构成经向垂直反环流,加强了锋区的上升运动.(3)4次暴雨过程梅雨锋都为相当位温密集带,在对流层低层垂直方向上近似直立分布.由于受冷空气影响,第一、三、四次过程梅雨锋区具有较明显的温度梯度,低层锋区向北倾斜;相反,没有冷空气的作用,第二次过程锋区无温度梯度,梅雨锋向南倾斜.     

“09.11.10”石家庄特大暴雪中尺度风场分析

利用常规观测、雷达资料以及四维变分方法反演的风场资料,对2009年11月10-12日石家庄特大暴雪过程的形势场和中尺度风场结构进行了详细分析.从影响系统来看,此次特大暴雪过程分为两个阶段:回流降雪和西来槽降雪.回流降雪是特大暴雪的主要时段,此阶段西部山区降雪明显大于东部平原;而西来槽降雪阶段全区降雪比较均匀.由雷达反射率因子和径向速度可见:10日降雪具有对流性质,而且回波不断地自西部山区向石家庄市区移动,产生“列车效应”,造成市区及西部降雪强度较大;11-12日回波强度弱,降雪强度也较弱.分析雷达四维变分反演风场得到如下结论:(1)反演风场能够准确展现东风影响的时间和高度、西来槽影响的始末,对预报员定性外推降雪的强度起到非常好的参考作用.(2)低层水平反演风场上,存在一个比较窄的东风带,回波沿东风带自西向东移动,石家庄市区处于北到东北风的“回流墙”附近,东移回波在此堆积,移速减慢,影响时间较长;同时,市区附近存在风向性和风速性辐合,致使回波在石家庄附近加强或维持.(3)反演风场垂直剖面图上,东风回流降雪阶段,低层东风区上空存在一个“反气旋”,强回波位于“反气旋”所包围的范围.     

对转压气机三维掠动叶优化设计

为探索三维掠动叶降低对转压气机二次流损失的潜力,进一步提高对转压气机气动性能,基于近似函数与遗传算法,针对某对转压气机双排转子在整机环境下进行三维掠动叶优化设计,并对优化前后流场进行对比分析。优化成功的得到了双排“S”形掠动叶,结果表明:三维掠动叶有效改善了双排动叶吸力面径向二次流,减小了吸力面低速区,提高了对转压气机性能,优化工况点整机效率提高0.6%,全工况范围内效率均有所提高;三维掠动叶提高对转压气机效率的根本原因是其对径向负荷分配的重新调整,将叶展下方流动较差区域负荷移至叶展上方,改善流场的同时保证对转压气机负荷不变。      

海水养殖水温对冷空气的响应及水温预报

开展冷空气对海水养殖水温的影响及水温预测预报,可为水产养殖灾害监测预警提供科学依据。该文以东沙海水养殖场为试验基地,对2010～2011年整个冬季冷空气活动期间水温气温变化进行了对比分析,并对不同强度、伴随不同天气现象的冷空气影响下水温的变化情况进行讨论。结果表明:该冬季共有9次冷空气影响,水温变化趋势与气温相似,但变幅小于气温,而且有明显的滞后性;冷空气对水温有显著的影响,影响程度与冷空气强度、伴随的天气现象及水的深度有关,冷空气越强,水温下降幅度就越大;不同天气条件对水温的影响不一样,晴天时水温下降较小,阴天水温降幅增大,寒潮影响时水温大幅度下降,冷空气影响结束后1～2 d,水温降到最低值;采用逐步回归分析方法,建立了冬季养殖塘水下0.5 m和1 m的水温预报模式,经独立样本检验,准确率高,可以应用于业务服务。     

Intensified Eastward and Northward Propagation of Tropical Intraseasonal Oscillation over the Equatorial Indian Ocean in a Global Warming Scenario

Northward propagation in summer and eastward propagation in winter are two distinguished features of tropical intraseasonal oscillation(TISO) over the equatorial Indian Ocean.According to numerical modeling results,under a global warming scenario,both propagations were intensified.The enhanced northward propagation in summer can be attributed to the enhanced atmosphere-ocean interaction and the strengthened mean southerly wind;and the intensified eastward propagation in winter is associated with the enhanced convection-wind coupling process and the strengthened equatorial Kevin wave.Future changes of TISO propagations need to be explored in more climate models.     

Earth System Model FGOALS-s2: Coupling a dynamic global vegetation and terrestrial carbon model with the physical climate system model

Earth System Models （ESMs） are fundamental tools for understanding climate-carbon feedback. An ESM version of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS） was recently developed within the IPCC AR5 Coupled Model Intercomparison Project Phase 5 （CMIP5） modeling framework, and we describe the development of this model through the coupling of a dynamic global vegetation and terrestrial carbon model with FGOALS-s2. The performance of the coupled model is evaluated as follows. The simulated global total terrestrial gross primary production （GPP） is 124.4 PgC yr-I and net pri- mary production （NPP） is 50.9 PgC yr-1. The entire terrestrial carbon pools contain about 2009.9 PgC, comprising 628.2 PgC and 1381.6 PgC in vegetation and soil pools, respectively. Spatially, in the tropics, the seasonal cycle of NPP and net ecosystem production （NEP） exhibits a dipole mode across the equator due to migration of the monsoon rainbelt, while the seasonal cycle is not so significant in Leaf Area Index （LAI）. In the subtropics, especially in the East Asian monsoon region, the seasonal cycle is obvious due to changes in temperature and precipitation from boreal winter to summer. Vegetation productivity in the northern mid-high latitudes is too low, possibly due to low soil moisture there. On the interannual timescale, the terrestrial ecosystem shows a strong response to ENSO. The model- simulated Nifio3.4 index and total terrestrial NEP are both characterized by a broad spectral peak in the range of 2-7 years. Further analysis indicates their correlation coefficient reaches -0.7 when NEP lags the Nifio3.4 index for about 1-2 months.     

北京一次持续性雾霾过程的阶段性特征及影响因子分析

利用北京地区高时间分辨率观测资料对2009年11月3—8日一次持续性雾霾天气过程中的气象因素和气溶胶演变特征进行了分析。结果表明,该次雾霾过程具有明显的阶段性特征,前期以霾为主,中期发展为雾霾交替,后期随着相对湿度减小再次转换为霾并最终消散。边界层逆温是低能见度过程形成的必要条件,但并不最终决定雾霾低能见度强度。相对湿度和PM_2.5浓度是决定能见度大小的两个关键影响因子,对能见度的影响体现出阶段性特征。大部分时段PM_2.5浓度是影响能见度的主要因子,当能见度小于1 km时,能见度变化更多受相对湿度影响。不同的情景计算表明,控制PM_2.5浓度对于改善本次过程的能见度有重要作用。     

The amino acid composition of the Sutter's Mill CM2 carbonaceous chondrite

We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM2) recovered prior to heavy rains that fell April 25–26, 2012, and two other meteorite fragments, SM12 and SM51, that were recovered postrain. We also determined the abundance, enantiomeric, and isotopic compositions of amino acids in soil from the recovery site of fragment SM51. The three meteorite stones experienced terrestrial amino acid contamination, as evidenced by the low d/l ratios of several proteinogenic amino acids. The d/l ratios were higher in SM2 than in SM12 and SM51, consistent with rain introducing additional l‐ amino acid contaminants to SM12 and SM51. Higher percentages of glycine, β‐alanine, and γ‐amino‐n‐butyric acid were observed in free form in SM2 and SM51 compared with the soil, suggesting that these free amino acids may be indigenous. Trace levels of d +l‐ β‐aminoisobutyric acid (β‐AIB) observed in all three meteorites are not easily explained as terrestrial contamination, as β‐AIB is rare on Earth and was not detected in the soil. Bulk carbon and nitrogen and isotopic ratios of the SM samples and the soil also indicate terrestrial contamination, as does compound‐specific isotopic analysis of the amino acids in the soil. The amino acid abundances in SM2, the most pristine SM meteorite analyzed here, are approximately 20‐fold lower than in the Murchison CM2 carbonaceous chondrite. This may be due to thermal metamorphism in the Sutter's Mill parent body at temperatures greater than observed for other aqueously altered CM2 meteorites.     

Presolar grains in the CM2 chondrite Sutter's Mill

The Sutter's Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter's Mill sections, SM43, SM51, SM2‐4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C‐anomalous grains and one O‐anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C‐anomalous grains and 2 ppm for presolar oxides. Thirty‐one silicon carbide (SiC), five carbonaceous grains, and one Al‐oxide (Al₂O₃) were confirmed based on their elemental compositions determined by C‐N‐Si and O‐Si‐Mg‐Al isotopic measurements. The overall abundance of SiC grains in Sutter's Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter's Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2‐4 shows heterogeneous distributions of presolar SiC grains (12–54 ppm) in different matrix areas, indicating that the fine‐grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.