ENSO发展和衰减阶段的陕西夏季降水异常特征

利用1961—2008年陕西78个气象站夏季 (6—8月) 降水资料、NCEP/NCAR位势高度场和风场月平均再分析资料,采用合成及相关分析方法探讨ENSO发展和衰减阶段对陕西夏季降水异常的影响,以期为陕西夏季降水的气候预测提供线索和依据。结果表明:陕西夏季降水异常对ENSO发展和衰减阶段的响应存在显著差异,El Ni?o发展阶段和La Ni?a衰减阶段,陕西夏季降水偏少; El Ni?o衰减阶段和La Ni?a发展阶段,陕西夏季降水偏多; ENSO不同阶段对陕西7月降水影响最为显著。比较而言,El Ni?o事件对陕西夏季降水的影响更加显著。在El Ni?o衰减、La Ni?a发展阶段,西太平洋副热带高压偏强、偏西,东亚夏季风偏弱,而在El Ni?o发展、La Ni?a衰减阶段,西太平洋副热带高压偏弱、偏东,东亚夏季风偏强,El Ni?o过程对东亚夏季风强弱的影响更加显著。ENSO发展和衰减阶段通过影响大气环流变化和东亚夏季风的强弱,进而影响陕西夏季降水。     

近几年中尺度动力学研究进展

近几年,中尺度气象由于在逐日天气预报中的重要作用和在气象灾害预报中的显著贡献,已经成为一个热门的研究课题.中尺度气象研究并预测中尺度天气系统的发生发展及其引发的灾害性天气,如暴雨、冰雹、龙卷风等.本文主要总结了2007年以来我国在中尺度研究中取得的显著性成果.主要包括:波动、涡旋、锋面、稳定性、Q矢量和不变量.在波动方面包括重力波的形成和传播的研究,包含旋转Rossby波、混合低频旋转Rossby波和高频惯性重力波在内的台风波动以及考虑水汽作用的中尺度波作用守恒.涡旋部分主要介绍了青藏高原低涡(TPV)和热带气旋内部的涡旋问题.除了涡旋之外,锋面在中国也是一个关键系统.在锋面方面的进展有:梅雨锋中的β中尺度双雨带机制的产生和维持的实验性研究,以及基于广义位温的锋生函数的提出,这些成果使得对锋生过程的描述更接近于实际大气状况.在不稳定问题上,主要介绍了采用Energy-Casimir方法建立的拟能量波作用方程和基本气流具有线性和非线性切变时的横波扰动的不稳定.关于Q矢量,介绍了从地转Q矢量,半地转Q矢量到非地转Q矢量,非地转湿Q矢量的发展,以及由湿地转Q矢量和垂直风切变耦合得到的新型散度方程.最后,讨论了有关质点的两个不变量位温和位涡的相关研究新进展.     

Two modes of the silk road pattern and their interannual variability simulated by LASG/IAP AGCM SAMIL2.0

In this study, two modes of the Silk Road pattern were investigated using NCEP2 reanalysis data and the simulation produced by Spectral Atmospheric Circulation Model of IAP LASG, Version 2 (SAMIL2.0) that was forced by SST observation data. The horizontal distribution of both modes were reasonably reproduced by the simulation, with a pattern correlation coefficient of 0.63 for the first mode and 0.62 for the second mode. The wave train was maintained by barotropic energy conversion (denoted as CK) and baroclinic energy conversion (denoted as CP) from the mean flow. The distribution of CK was dominated by its meridional component (CK _y ) in both modes. When integrated spatially, CK _y was more efficient than its zonal component (CK _x ) in the first mode but less in the second mode. The distribution and efficiency of CK were not captured well by SAMIL2.0. However, the model performed reasonably well at reproducing the distribution and efficiency of CP in both modes. Because CP is more efficient than CK, the spatial patterns of the Silk Road pattern were well reproduced. Interestingly, the temporal phase of the second mode was well captured by a single-member simulation. However, further analysis of other ensemble runs demonstrated that the successful reproduction of the temporal phase was a result of internal variability rather than a signal of SST forcing. The analysis shows that the observed temporal variations of both CP and CK were poorly reproduced, leading to the low accuracy of the temporal phase of the Silk Road pattern in the simulation.     

Steric sea level change in twentieth century historical climate simulation and IPCC-RCP8.5 scenario projection: A comparison of two versions of FGOALS model

To reveal the steric sea level change in 20th century historical climate simulations and future climate change projections under the IPCC’s Representative Concentration Pathway 8.5 (RCP8.5) scenario, the results of two versions of LASG/IAP’s Flexible Global Ocean-Atmosphere-Land System model (FGOALS) are analyzed. Both models reasonably reproduce the mean dynamic sea level features, with a spatial pattern correlation coefficient of 0.97 with the observation. Characteristics of steric sea level changes in the 20th century historical climate simulations and RCP8.5 scenario projections are investigated. The results show that, in the 20th century, negative trends covered most parts of the global ocean. Under the RCP8.5 scenario, global-averaged steric sea level exhibits a pronounced rising trend throughout the 21st century and the general rising trend appears in most parts of the global ocean. The magnitude of the changes in the 21st century is much larger than that in the 20th century. By the year 2100, the global-averaged steric sea level anomaly is 18 cm and 10 cm relative to the year 1850 in the second spectral version of FGOALS (FGOALS-s2) and the second grid-point version of FGOALS (FGOALS-g2), respectively. The separate contribution of the thermosteric and halosteric components from various ocean layers is further evaluated. In the 20th century, the steric sea level changes in FGOALS-s2 (FGOALS-g2) are largely attributed to the thermosteric (halosteric) component relative to the pre-industrial control run. In contrast, in the 21st century, the thermosteric component, mainly from the upper 1000 m, dominates the steric sea level change in both models under the RCP8.5 scenario. In addition, the steric sea level change in the marginal sea of China is attributed to the thermosteric component.     

黑龙江省封冻前土壤底墒趋势变化分析

利用黑龙江省1981-2010年的土壤湿度数据,以富锦县、龙江县、双城县、黑河市、海伦县为代表点,分析了黑龙江省东、西、南、北、中各区域封冻前(11月8日)0～30 cm土层土壤湿度的趋势变化和干湿变化,采用线性趋势、5年滑动平均和Mann-Kendall法检验变化趋势,利用Mann-Kendall和Yamamoto法对土壤湿度变化趋势进行突变点检验.结果表明:封冻前0～30 cm土层各地土壤湿度在30年间均有不同程度下降,西部龙江县下降剧烈,中部海伦县较剧烈,北部黑河市和南部双城县次之,上述代表点20 cm土层土壤湿度下降均达到了P＜0.05以内的显著水平,东部富锦县下降趋势最弱;经Mann-Kendall法检验,0～30 cm土层龙江县、海伦县土壤湿度出现了下降的突变区域,其余代表点的土壤湿度变化趋势在近几年中逐渐接近或已经超越了显著线;1994年是龙江县10 cm、20 cm土壤湿度下降的突变时期;黑龙江省各地土壤湿度的下降与封冻前一段时期内气温和降水变化密切相关,还与土壤物理性质的恶化等因素有关.     

不同积雪深度下地面温度与雪面温度的相关

基于新疆昌吉州5个国家气象站2008—2010年积雪深度大于等于0 cm的实测地面温度与雪面温度,对0 cm地面温度（含最高、最低）、雪面温度（含最高、最低）及云量、日照时数、雪深进行统计分析,找出不同积雪深度下地面温度与雪面温度的关系,并以阜康市天池气象站2011年所有积雪日数据对关系模型作检验。结果显示：地面温度与雪面温度的关系有3个雪深分层：5 cm以下、6~40 cm和40 cm以上,积雪深度为0~5 cm时,地面温度与雪面温度差值很小,受雪深及天气条件影响明显,雪深6~40 cm,主要受雪深影响,雪深超过40 cm,地面温度趋于定值。     

高清气象影视虚拟演播室系统设计与调试

以华风集团高清虚拟演播室建设项目为案例,论述了高清虚拟演播室技术在系统建设、系统调试、天气预报节目业务实现环节需要重点解决的几个问题和难点。根据气象电视节目制作要求,在从虚拟演播室系统系统建设到节目制作业务化的整个过程中,重点解决了音频系统延时量计算、绿箱景区施工、绿箱景区灯光布局、绿箱色键抠像调试、摄像机定位与跟踪调试、气象数据调用与转换共6个关键性技术问题。此次业务系统实践的成功是虚拟演播室技术在全国气象影视行业高清节目制作中的应用和推广的很好尝试。     

基于SPEI的中国西南地区1961-2012年干旱变化特征分析

利用1961—2012年中国西南地区86个气象站逐月降水量和平均气温资料,引入一个新的干旱指数——标准化降水蒸散指数(SPEI)作为干旱等级划分指标,研究了1961—2012年该地区不同时间尺度干旱的变化特征。结果表明:该地区12个月尺度干旱频率在云贵交界区呈显著增加趋势,其他区域变化不显著且不一致;少雨期(11—4月)6个月尺度干旱频率在全区显著增加,而在多雨期(5—10月)大部分区域干旱频率呈缓慢减少趋势,减少最明显的区域在四川南部;3个月尺度干旱频率在春季变化不明显,在秋季和冬季显著增加,其中2000—2012年的增加趋势尤为显著,干旱化趋势严重。     

Solar cycle distribution of strong solar proton events and the related solar-terrestrial phenomena

We investigated the solar cycle distribution of strong solar proton events (SPEs, peak flux ≥1000 pfu) and the solar-terrestrial phenomena associated with the strong SPEs during solar cycles 21–23. The results show that 37 strong SPEs were registered over this period of time, where 20 strong SPEs were originated from the super active regions (SARs) and 28 strong SPEs were accompanied by the X-class flares. Most strong SPEs were not associated with the ground level enhancement (GLE) event. Most strong SPEs occurred in the descending phases of the solar cycles. The weaker the solar cycle, the higher the proportion of strong SPES occurred in the descending phase of the cycle. The number of the strong SPEs that occurred within a solar cycle is poorly associated with the solar cycle size. The intensity of the SPEs is highly dependent of the location of their source regions, with the super SPEs (≥20000 pfu) distributed around solar disk center. A super SPE was always accompanied by a fast shock driven by the associated coronal mass ejection and a great geomagnetic storm. The source location of strongest GLE event is distributed in the well-connected region. The SPEs associated with super GLE events (peak increase rate ≥100%) which have their peak flux much lower than 10000 pfu were not accompanied by an intense geomagnetic storm.     

NanoSIMS analysis of organic carbon from the Tissint Martian meteorite: Evidence for the past existence of subsurface organic‐bearing fluids on Mars

Two petrographic settings of carbonaceous components, mainly filling open fractures and occasionally enclosed in shock‐melt veins, were found in the recently fallen Tissint Martian meteorite. The presence in shock‐melt veins and the deuterium enrichments (δD up to +1183‰) of these components clearly indicate a pristine Martian origin. The carbonaceous components are kerogen‐like, based on micro‐Raman spectra and multielemental ratios, and were probably deposited from fluids in shock‐induced fractures in the parent rock of Tissint. After precipitation of the organic matter, the rock experienced another severe shock event, producing the melt veins that encapsulated a part of the organic matter. The C isotopic compositions of the organic matter (δ¹³C = ?12.8 to ?33.1‰) are significantly lighter than Martian atmospheric CO₂ and carbonate, providing a tantalizing hint for a possible biotic process. Alternatively, the organic matter could be derived from carbonaceous chondrites, as insoluble organic matter from the latter has similar chemical and isotopic compositions. The presence of organic‐rich fluids that infiltrated rocks near the surface of Mars has significant implications for the study of Martian paleoenvironment and perhaps to search for possible ancient biological activities on Mars.