关于CAS FGOALS-f3-L模式中青藏高原地表温度偏差的归因分析

中国科学院全球海洋-大气-陆地耦合模式(FGOALS-f3-L)参加了耦合模式比较计划的第六阶段(CMIP6)试验,但是其对关键气候敏感地区青藏高原的地表温度的再现能力还不清楚.这项研究用再分析资料CFSR评估了FGOALS-f3-L模式对青藏高原地表温度的再现能力.结果表明,FGOALS-f3-L可以合理模拟整个高原上年平均地表温度的空间分布,但低估了整个高原上年平均地表温度.模拟的地表温度在整个高原上冬春季表现为冷偏差,夏秋季表现为暖偏差.基于地表能量平衡方程的进一步定量分析表明,地表反照率反馈(SAF)项极大地贡献了高原西部年平均,冬春季平均地表温度的冷偏差,而对高原东部是暖偏差贡献.与SAF项相比,地表感热项对地表温度偏差的贡献几乎相反,这大大抵消了SAF项引起的偏差.云辐射强迫项对高原东部的年平均和季节平均弱冷偏差有很大贡献.与高估的水蒸气含量有关的长波辐射项造成了夏秋季整个高原上大部分的暖偏差.该研究表明,提高FGOALS-f3-L中的陆面和云过程对降低高原上地表温度偏差至关重要.     

The compressibility of Fe- and Al-bearing phase D to 30 GPa

High-pressure in situ X-ray diffraction experiment of Fe- and Al-bearing phase D (Mg_0.89Fe_0.14Al_0.25Si_1.56H_2.93O₆) has been carried out to 30.5 GPa at room temperature using multianvil apparatus. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields values of V ₀ = 86.10 ± 0.05 ų; K ₀ = 136.5 ± 3.3 GPa and K′ = 6.32 ± 0.30. If K′ is fixed at 4.0 K ₀ = 157.0 ± 0.7 GPa, which is 6% smaller than Fe–Al free phase D reported previously. Analysis of axial compressibilities reveals that the c-axis is almost twice as compressible (K _c  = 93.6 ± 1.1 GPa) as the a-axis (K _a  = 173.8 ± 2.2 GPa). Above 25 GPa the c/a ratio becomes pressure independent. No compressibility anomalies related to the structural transitions of H-atoms were observed in the pressure range to 30 GPa. The density reduction of hydrated subducting slab would be significant if the modal amount of phase D exceeds 10%.     

Analysis of Cloud Scale Error of Low Resolution Satellite Based on GF-4 and Its Influence on Downward Radiation Calculation

In order to study the scale error of low resolution meteorological satellite cloud detection and its impact on the calculation of downlink radiation, cloud detection using high resolution stationary satellite GF-4 data and error analysis were carried out. Firstly, the cloud detection of GF-4 data is carried out by using visible channel threshold method and time series method, and the error of cloud detection results of Himawari-8 and FY-2 (FY-2G, FY-2E) is analyzed based on the results of GF-4 cloud detection.In the study area, FY-2G, FY-2E and Himawari-8 cloud images could distinguish the clouds and clear sky. The main reason for the error was the scale effect produced by different spatial resolution satellites(the differences caused by cloud detection algorithms are not discussed here).Most of the errors occurred in the areas of thin clouds and broken clouds.High resolution data could detect broken clouds, while low resolution data lead to false and missed detection. On this basis, the error of remote sensing calculation of short wave radiation was analyzed,and it was found that the error of the actual cloud amount in the pixel would bring significant error to the estimation of the downward radiation.The relative error of the instantaneous downward radiation in the selected test area was -173.52%, and the maximum relative error of shortwave radiation was -20.20%.The results show that the high resolution stationary satellite data can significantly improve the estimation accuracy of the downlink shortwave radiation in the regions with more broken clouds.     

青海湖流域瓦颜山湿地辐射平衡和地表反照率变化特征

利用2014年5月至2015年11月青海湖流域瓦颜山湿地观测的辐射资料,综合分析了辐射相关因子的变化特征。结果表明：瓦颜山湿地总辐射和净辐射的最大值都出现在7月,最小值都出现在12月;大气长波辐射最大值出现在8月,最小值出现在12月;地面长波辐射最大值出现在7月,最小值出现在2月。阴天对总辐射和地面反射辐射削弱作用比较明显,对大气长波辐射增强作用明显,对地面长波辐射和净辐射的影响季节差异性很大。瓦颜山湿地地表反照率的年均值为0.26。在无积雪覆盖条件下,地表反照率在冻结期明显大于消融期,最大值出现在12月。夏季地表反照率均值为0.185,略小于下垫面同为草甸的青藏高原唐古拉站。在暖季,土壤水分也是影响高寒湿地地表反照率变化的重要因子,随着表层土壤含水量的增加,地表反照率随之减小。     

一种新型测地线双锥天线的研究

介绍了一种新型测地线双锥天线,该天线能够实现全方位面上的波束扫描,具有广阔的应用空间。采用几何光学法结合测地线理论分析了其工作原理,重点阐述了圆柱面上射线传输路径的问题,并对该天线在单端口和双端口激励情况下的方向图分别进行了分析和计算。在以上基础上,设计加工完成了一款工作在6～8 G Hz的新型测地线双锥天线,给出了其具体结构和尺寸。理论结果与实测结果具有较好的一致性,表明了几何光学法在测地线双锥天线分析和设计中的适用性。     

2017年西藏米林MS6.9地震前地磁垂直强度极化异常特征

基于中国大陆65 个地磁台站秒采样观测资料,利用地磁垂直强度极化方法提取了2017年西藏米林M_S6.9 地震震中及附近区域超低频电磁异常信号并分析其时空演化特征。结果显示:米林M_S6.9 地震前在青藏高原出现了大范围的地磁垂直强度极化高值异常,异常过程共持续9天;高值异常开始于2017 年10 月30 日,高值持续3 天之后出现短时间下降,随即转折上升,再次出现高值异常并持续了4 天,在此过程中各高值台站的时序曲线呈现出单峰或双峰的形态。空间分布图显示高值异常在中国大陆西部区域反复出现,尤其是在青藏高原巴颜喀拉地块与羌塘地块的交界处。异常呈“出现—扩大—收缩—消失—扩大—消失”的演化过程,10月31日异常面积达到最大值。异常过程结束后10天发生了西藏米林M_S6.9地震,震中距离10 月31 日异常阈值线5 km。综合分析认为,此次异常与米林地震具有较强的时空相关性,是可靠的地震电磁前兆异常。      

Estimating the Great Lakes net radiation using satellite remote sensing and MERRA reanalysis

ABSTRACT

The net all-wave radiation of the Great Lakes (GL) is a key to understanding the effects of climate change on the GL. There is a high possibility of underestimating the net all-wave radiation of the GL when using existing methodologies with inputs from near-shore and land-based meteorological data. This study provides the first technique to estimate net all-wave radiation over the GL from July 2001 to December 2014 using a combination of data from satellite remote sensing, reanalysis data sets, and direct measurements. The components of the surface radiation budget estimated from the proposed method showed good statistical agreement. The instantaneous net radiation estimated by our methods was compared with the in situ measurements from June 2008 to April 2012 (Stannard Rock Lighthouse: SR) and September 2009–April 2011 (Spectacle Reef Lighthouse: SP). The comparisons from SR and SP also showed strong statistic agreement (R²?=?0.74 and 0.7; RMSE?=?9.26 and 10.60?W?m^?2 respectively). Monthly spatial variations of net shortwave radiation varied with cloud cover and surface albedo while net longwave radiation varied with the temperature difference between the water surface and the atmosphere.     

汶川MS8.0级地震前后ULF电磁辐射频谱特征研究

本文基于电磁波频谱理论研究方法,对2008年四川汶川M_S8.0地震前后金河、剑阁及郑州二砂三个电磁波台站的观测资料进行FFT和小波变换分析,研究了电磁辐射数据快速傅里叶频谱变化特征和在不同尺度下小波变化的分解,发现在汶川地震前确实有异常信息存在.结果表明:(1) FFT动态谱图像说明,地震前电磁波频谱变化特征较明显,在时间、频段上均显示了阶段性进程特征,且随着震中距的增大,辐射能量越小,异常出现的时间越晚;(2) 小波分解显示了地震前电磁波异常信号低频部分出现的时间较早;距震中较近的台站,异常信息在高频部分相对明显;距震中稍远的台站,异常信息在低频部分相对明显.     

Distributed hydrological modelling of a heavily glaciated Alpine river basin

Abstract

A glacier submodel was successfully integrated into the distributed hydrological model WaSiM-ETH to simulate the discharge of a heavily glaciated drainage basin. The glacier submodel comprises a distributed temperature index model including solar radiation to simulate the melt rate of glaciated areas. Meltwater and rainfall are transformed into glacier discharge by using a linear reservoir approach. The model was tested on a high-alpine sub-basin of the Rhone basin (central Switzerland) of which 48% is glaciated. Continuous discharge simulations were performed for the period 1990–1996 and compared with hourly discharge observations. The pronounced daily and annual fluctuations in discharge were simulated well. The obtained efficiency criterion, R², exceeds 0.89 for all years. The good performance of the glacier submodel is also demonstrated by integrating it into the hydrological model PREVAH.     

The earliest occurrence of peltasperms in the basal Permian strata of the North China Block and the radiation of this group

The peltasperm foliage Autunia naumannii (Gutbier) Kerp and possible peltasperm fructifications are for the first time described from the uppermost Taiyuan Formation of earliest Permian age near Wuda, Inner Mongolia. This is the oldest record of this group on the North China Block (Sino‐Korean Platform), indicating an early migration into this area. Data of other occurrences in China demonstrate independent radiations of the group in Cathaysia. All known records indicate that peltasperms probably originated in the tropical extrabasinal areas of Euramerica, and subsequently migrated within the tropical belt and experienced independent regional radiations in Europe, the southwestern United States and on the North China Block. The present discovery of Autunia naumannii (Gutbier) Kerp in China adds a common floral component between the Euramerican and Cathaysian floras, providing more evidence indicating mutual migration of floral elements between Cathaysia and Euramerica. Copyright © 2013 John Wiley & Sons, Ltd.