集合数值天气预报的研究进展

集合预报是目前国外广泛应用的一种新的数值预报技术,国内由于计算条件的限制,集合预报的研究应用起步较晚,目前虽已取得了一些研究成果,但还没有广泛的应用到实际的业务预报之中。集合预报的应用,在天气预报上主要是概率预报,另外在“目标观测”、资料同化等方面也有广泛应用。集合概率预报的一系列适用的验证,增加了概率预报的信度。     

阿拉善宗乃山岩体东南缘花岗岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

阿拉善宗乃山岩体东南缘分布多种类型的花岗岩,本文主要采用岩相学、激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)锆石U-Pb定年、岩石地球化学等技术手段,对宗乃山岩体东南缘岩石类型、年代学、源岩特征以及构造背景进行了研究。结果表明:岩石类型主要为碱性-钙碱性准铝质花岗岩和闪长岩;单颗粒锆石分析获得黑云母斜长花岗岩年龄为236.8±1.9 Ma~249.7±2.6 Ma,片麻状花岗岩年龄为268.1±1.1 Ma,岩体成岩时期主要为华力西晚期和印支期早期,具有多期侵入的特征。该岩体岩石源岩为I型花岗岩,源于地壳火山弧区和同碰撞区,表明由于洋壳俯冲作用,在宗乃山东南缘形成了岛弧花岗岩侵入体。LA-ICP-MS锆石U-Pb定年技术为洋壳俯冲提供了年代学约束,确定了研究区碰撞时间为早于236.8±1.9 Ma。     

全极化探地雷达地下管道分类识别技术

常规探地雷达大多数是单极化雷达,单极化雷达只能获得单极化数据,对复杂环境中管道准确快速地识别比较困难。为了解决此问题,本文采用了全极化探地雷达识别管道的方法,提取了单一管道目标、多个管道目标中任何一个管道目标和受其他目标影响的管道目标的极化属性。结果表明,全极化探地雷达技术对处于极化属性受到影响环境下的管道目标均能较好地识别。因此,全极化探地雷达能够获得更加全面的目标体极化信息,有效地解决了复杂环境中管道准确快速识别比较困难的问题。     

基于环形扫面测量的三维直流电阻率法任意各向异性模型响应特征

高精度地下任意各向异性介质电性分布特征识别是当前的热门研究课题。本文以国内外前人工作为基础,基于非结构化网格,利用基于梯度恢复的后验误差估计指导网格自适应细化过程,实现了直流电阻率法三维有限元数值模拟。通过与一维模型半解析解的对比,验证了本文算法的有效性。考虑到电各向异性介质在观测中存在视电阻率反常现象,本文采用了环形扫面测量方法。通过对几种典型各向异性模型的模拟分析,得到了相应的各向异性影响规律和识别特征,各向异性主轴电阻率之间的比值大小决定了椭圆型视电阻率极性曲线长轴与短轴的比值大小,主轴电阻率的旋转方向会改变视电阻率极性曲线的形状。本文的算法研究及数值模拟技术可为直流电法数据精细处理和解释提供技术支撑。     

台湾以东黑潮的低频变化及机制研究

本文基于AVISO（Archiving, Validation and Interpretation of Satellite Oceanographic data）1993-2015年间的海表面绝对动力高度数据,研究了台湾以东黑潮的低频变化特征,并探讨了影响其变化的机制。结果表明,台湾以东多年平均的黑潮流幅值约为136 km,表层流量值约为7.75×104 m2/s,对应的标准差分别为28 km和2.14×104 m2/s。台湾以东黑潮不仅具有显著的季节变化特征,还具有显著的年际变化特征。功率谱分析结果表明,台湾以东黑潮表层流量具有1 a和2.8 a的显著周期。空间上,台湾东南部黑潮的年际变化幅度比东北部强烈。相关性及合成分析结果表明,台湾以东黑潮的年际变化与PTO（Philippines-Taiwan Oscillation）之间存在显著的相关性。PTO年际震荡所导致的副热带逆流区反气旋式涡旋与气旋式涡旋的相对强度是影响台湾以东黑潮年际变化的主要动力因素。     

水温和盐度对长牡蛎“海大1号”早期生长发育的影响

为确定长牡蛎新品种"海大1号"苗种繁育的最适环境条件,研究了盐度对其胚胎发育的影响以及盐度、水温对其幼虫生长、存活率和附着率的影响。结果表明:长牡蛎"海大1号"受精卵孵化的最适盐度为30~35,孵化率最高可达90%。幼虫生长的适宜盐度为20~35,最适盐度为20~30;存活的适宜盐度为20~35,最适盐度为20~25;幼虫附着的适宜盐度为20~35,最适盐度为25~30;对长牡蛎"海大1号"幼虫生长、存活、附着的适宜水温分别为为20~30℃、20~25℃、20~30℃,最适水温分别为30、25、30℃,高温35℃时幼虫全部死亡。综上,长牡蛎"海大1号"苗种培育的适宜盐度为20~35,适宜水温为20~25℃。上述结果为长牡蛎"海大1号"规模化苗种繁育提供了重要的基础资料。     

北极径流增加对大西洋经向翻转环流影响的模拟研究

观测显示过去几十年间北极入海径流呈现增加趋势,CMIP5耦合模式预测表明21世纪北极入海径流仍会增加,在RCP8.5路径下,21世纪末北极入海径流量将会是1950年的1.4倍。本文利用冰-海耦合数值模式研究了北极径流增加对大西洋经向翻转环流的影响。基于两个数值实验的结果表明,如果北极入海径流按每年0.22%的速度（与RCP8.5路径下的速度相当）增加,大西洋经向翻转环流的强度在100、150和200年后将会分别减弱0.6（3%）、1.2（7%）和1.8（11%） Sv。北极入海径流增加导致大西洋经向翻转环流减弱的主要原因是,北极入海径流增加的淡水被输运到北大西洋后,会抑制北大西洋深层水的生成,这也会导致北大西洋深层水海水年龄的增加。     

Effects of temperature and salinity on survival,growth and DNA methylation of juvenile Pacific abalone,Haliotis discus hannai Ino

Temperature and salinity are two of the most potent abiotic factors infl uencing marine mollusks.In this study,we investigated the individual and combined ef fects of temperature and salinity on the survival and growth of juvenile Pacifi c abalone,Haliotis discus hannai Ino,and also examined the DNA methylation alteration that may underpin the phenotypic variation of abalone exposed to dif ferent rearing conditions.The single-factor data showed that the suitable ranges of temperature and salinity were 16–28°C at a constant salinity of 32,and 24–40 at a constant temperature of 20°C,respectively.The two-factor data indicated that both survival and growth were signifi cantly af fected by temperature,salinity and their interaction.The optimal temperature-salinity combination for juveniles was 23–25°C and 30–36.To explore environment-induced DNA methylation alteration,the methylation-sensitive amplifi ed polymorphism(MSAP)technique was used to analyze the genomic methylation profi les of abalone reared in optimal and adverse conditions.Neither temperature nor salinity induced evident changes in the global methylation level,but 67 and 63 dif ferentially methylated loci were identifi ed in temperature and salinity treatments,respectively.The between-group eigen analysis also showed that both temperature and salinity could induce epigenetic dif ferentiation in H.discus hannai Ino.The results of our study provide optimal rearing conditions for juvenile H.discus hannai Ino,and represent the fi rst step toward revealing the epigenetic regulatory mechanism of abalone in response to thermal and salt stresses.     

Change of annual extreme water levels and correlation with river discharges in the middle-lower Yangtze River: Characteristics and possible affecting factors

As one of the fastest developing regions in China, the middle-lower Yangtze River(MLYR) is vulnerable to floods and droughts. With obtained time series of annual highest water level(HWL), annual lowest water level(LWL) and the corresponding river discharges from three gauging stations in MLYR that covering the period 1987–2011, the current study evaluated the change characteristics of annual extreme water levels and the correlation with river discharges by using the methods of trend test, Mann-Whitney-Pettitt(MWP) test and double mass analysis. Major result indicated a decreasing/increasing trend for annual HWL/LWL of all stations in MLYR during the study period. A change point in 1999 was identified for annual HWL at the Hankou and Datong stations. The year 2006 was found to be the critical year that the relationship between annual extreme water levels and river discharges changed in the MLYR. With contrast to annual LWL in MLYR, further investigation revealed that the change characteristics of annual HWL were highly consistent with regional precipitation in the Yangtze River Basin, while the linkage with Three Gorges Dam(TGD) operation is not strong. Our observation also pointed out that the effect of serious down cutting of the riverbed and the enlargement of the cross-section area during the initial period of TGD operation caused the downward trend of the relationship between annual LWL and river discharge. Whereas, the relatively raised river water level before the flood season due to TGD regulation since 2006 explained for the changing upward trend of the relationship between annual HWL and river discharge.     

牛背梁自然保护区林线不同海拔巴山冷杉径向生长对气候变化的响应

近年来气候变化对秦岭植被的影响已得到众多研究的证实,牛背梁作为秦岭东部主脊和国家级自然保护区,该地区亚高山林线植被对气候变化的生态响应现状尚未得到广泛关注。依照树木年代学原理,进行响应分析并建立回归模型,探讨了牛背梁林线关键树种巴山冷杉（Abies fargesii）年表特征及对气候响应的海拔分异特征。结果表明：（1）随海拔升高,树木生长对气候的敏感性逐渐上升,但轮宽年表的同步性和信号强度呈先下降后上升的特点。（2）不同海拔树轮宽度年表的气候响应结果基本一致,对气温的敏感性均较降水强,敏感时段为当年2～8月,差异主要体现在,高海拔树木受生长季末期8月气温的影响较重,中海拔树木受生长季前期3～4月降水和上年冬季10～11月气温的促进,而低海拔树木受初春1～2月降水的限制作用明显。（3）对比分析低、中、高海拔3个回归模型中显著因子的变化趋势,发现气候变化可以促进巴山冷杉生长季的提前,但不同海拔树木的生长动态各异,说明研究区林线不同海拔巴山冷杉生长对全球变化可能具有不同的响应机制。