强震前的“干热异常”与地温、降水波及应变弱停

对近30年出现在中国西部及邻区的14次MS≥6.9强震前1年多内的地温场和降水场进行了分析。发现有如下共同规律：①在震前1年左右东亚地区会出现干热异常（3.2 m地温升高,同时降水距平为负值）,持续时间约为2-6个月,最大干热面积可达2-4×106km^2;②在震前0.5-1年左右我国的月降水距平%图和3.2 m地温距平的月际变温图上,可看到波长小于1 000 km的地温波和降水波,可称为＂超低频应力密度波（应变波）＂,它是致使岩石破裂的力源;③在震前0-2个月应变波的波长会停止缩短,振幅变小,且波动方向可有一个近90°的旋转,是＂应变弱停＂的表现。以上可视为孕震三步曲。依据上述统计事实本文提出了强震成因的假设：地外核中有一股热力极不稳定的Benard上升流体对其上的壳幔层形成顶托,造成地温升高,对流热传导系数变小,形成干热异常;岩石圈中脆性层的应力不断增大,致使出现不稳定波（应变波）;出现＂应变弱停＂时意味着强震即将爆发。

我国105°E以东地区M_S≥5.7级地震的孕震3步曲

根据近30年来,我国105°E以东(包括大陆架)M_s≥5.7级地震的震前逐月地温和降水演变特征,可以归纳出震前地气系统演变的共同特征:(1)可将"干热面积"最大月定为孕震3步曲的第一步.未来震级与干热面积有好的相关,最干点的经纬度与震中经纬度有一定的相关;(2)从地温、降水应变波出现到"正多负少"规则恢复可以作为孕震第二步的开始;(3)降水经向波长开始明显变长(甚至变为无限长),可称为孕震第三步,此时距地震发生仅剩0～2个月的时间.外核对流上升体(孕震体)对壳幔层顶托作用的地震成因说,可以较好地解释上述观测事实.

Large-scale circulation features associated with the heat wave over Northeast China in summer 2018

In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP–NCAR reanalysis data.The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China,and the related downward motions were directly responsible for the extreme high-temperature anomalies.The northwestward shift of the western Pacific subtropical high(WPSH)and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China.In addition,an anomalous Pacific–Japan pattern in the lower troposphere led to the northwestward shift of the WPSH,jointly favoring the anomalous geopotential height over Northeast China.Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes,respectively,and converged over Northeast China,leading to the enhancement of the geopotential height anomalies.

Three-dimensional numerical simulation of geothermal fi eld in space-wavenumber domain

Large-scale,fine,and efficient numerical simulation of a geothermal field plays an important role in geothermal energy development.Confronted with the problem of large computation and high storage requirements for complex underground models in a three-dimensional(3-D)numerical simulation of a geothermal fi eld,a mixed space-wavenumber domain 3-D numerical simulation algorithm is proposed in this paper.According to the superposition principle of temperature field,the geothermal field is decomposed into background and abnormal temperature fi elds for calculation.The uniform layered model is used to solve the background field.When the abnormal field is solved,the horizontal two-dimensional(2-D)Fourier transform is used to transform the 3-D diff erential equation satisfi ed by an abnormal field into a series of one-dimensional ordinary differential equations with diff erent wavenumbers,which greatly reduces the calculation and storage.The unit division of an ordinary diff erential equation is fl exible,and the calculation amount is small.The algorithm fully takes advantage of the effi ciency of the Fourier transform and the quickness of the catch-up method to solve linear equations with a fixed bandwidth,which effectively improves the computational efficiency.Compared with the COMSOL Multiphysics professional simulation finite element software,the time consumption and memory requirements of the algorithm proposed in this paper are reduced by multiple orders of magnitude in terms of ensuring accuracy and the same mesh division.The more the number of calculated nodes is,the more obvious is the advantage.We design models to study the thermal conductivity,heat fl ux boundary,regional tectonic morphology,and topographic relief of the geothermal fi eld distribution.A 3-D geophysical model is developed based on topographic elevation data,geothermal geology,and geophysical exploration data in the Qiabuqia area of Gonghe Basin,Qinghai Province,China.Numerical simulation of the geothermal fi eld in this area is realized,which shows that the algorithm is suitable for precise and effi cient simulation of an arbitrary complex terrain and geological conditions.

Preliminary Study on the Dynamic Variations of the Surface Thermal Flux before and after the M_S5.7 Earthquake of 2005 in Jiujiang City,Jiangxi Province

The temporal and spatial variations of surface latent heat flux(SLHF)and diagnostic air temperature at 2m before and after the M_S5.7 earthquake occurring on November 26,2005 in the area between Ruichang City and Jiujiang City,Jiangxi Province are summarized in this paper.It is found that before the earthquake significant SLHF anomalies and air temperature anomalies occurred in the epicentral area and its vicinity.The air temperature anomalies appeared from the 2nd to the 13th of November,2005 and were concentrated at the epicentral area and in its southern part.Then two days later,that is,from the 4th to the 15th of November 2005,significant SLHF anomalies occurred in the epicentral area and to its northern area where many lakes are distributed along the active faults.During the anomalous period,the SLHF and air temperature at 2m exceeded the sum of average daily value over 26 years and 1.5 times of its mean square deviation.Both anomalies had maintained for 12 days with a peculiar distribution related to the tectonic active zone.It is considered that both of air temperature anomalies and SLHF anomalies are correlated to the movement of thermal flux from underground prior to earthquake.SLHF anomalies occurred over wide regions covered with abundant water,whereas air temperature anomalies occurred over land.

Observations and Modeling of Incoming Longwave Radiation to Snow Beneath Forest Canopies in the West Tianshan Mountains, China

Forest canopy reduces shortwave radiation and increases the incoming longwave radiation to snowpacks beneath forest canopies. Furthermore, the effect of forest canopy may be changed by complex topography. In this paper, we measured and simulated the incoming longwave radiation to snow beneath forest at different canopy openness in the west Tianshan Mountains, China(43°16'N, 84°24'E) during spring 2013. A sensitivity study was conducted to explore the way that terrain influenced the incoming longwave radiation to snow beneath forest canopies. In the simulation model, measurement datasets, including air temperature, incoming shortwave radiation above canopy, and longwave radiation enhanced by adjacent terrain, were applied to calculate the incoming longwave radiation to snow beneath forest canopy. The simulation results were consistent with the measurements on hourly scale and daily scale. The effect of longwave radiation enhanced by terrain was important than that of shortwave radiation above forest canopy with different openness except the 20% canopy openness. The longwave radiation enhanced due to adjacent terrain increases with the slope increase and temperature rise. When air temperature(or slope) is relatively low, thelongwave radiation enhanced by adjacent terrain is not sensitive to slope(or air temperature), but the sensitivity increases with the decrease of snow cover area on sunny slope. The effect of longwave radiation is especially sensitive when the snow cover on sunny slope melts completely. The effect of incoming shortwave radiation reflected by adjacent terrain on incoming longwave radiation to snow beneath forest canopies is more slight than that of the enhanced longwave radiation.

A TDOA-Based Ultrasonic Absolute Localizing System of a Rail Robot in Greenhouse

In this paper,we present a method for localization of a rail autonomous pesticide spraying and sampling robot working in greenhouse using an absolute localization system.Design and implementation of the localization system comes from the usage of beacon systems each of which is composed of an RF single receiver and an ultrasonic transmitter.The RF single receiver gets the synchronization signal from the mobile robot,and the ultrasonic transmitter sends ultrasonic signal,thus the distance from the beacon to the ultrasonic receiver can be measured.The position of a beacon in coordinate system of robot can be calculated according to distance information from the beacons to two ultrasonic receivers which are mounted on the robot.Based on the coordinate transformation,the position of a mobile robot can be calculated from the beacon＇s absolute position information in the global coordinate system.Experiments demonstrate the effectiveness of the proposed method in real world applications.

A dual-pass data assimilation scheme for estimating surface fluxes with FY3A-VIRR land surface temperature

In this work, a dual-pass data assimilation scheme is developed to improve predictions of surface flux. Pass 1 of the dual-pass data assimilation scheme optimizes the model vegetation parameters at the weekly temporal scale, and Pass 2 optimizes the soil moisture at the daily temporal scale. Based on ensemble Kalman filter(EnKF), the land surface temperature(LST) data derived from the new generation of Chinese meteorology satellite(FY3A-VIRR) are assimilated into common land model(CoLM) for the first time. Six sites, Daman, Guantao, Arou, BJ, Miyun and Jiyuan, are selected for the data assimilation experiments and include different climatological conditions. The results are compared with those from a dataset generated by a multi-scale surface flux observation system that includes an automatic weather station(AWS), eddy covariance(EC) and large aperture scintillometer(LAS). The results indicate that the dual-pass data assimilation scheme is able to reduce model uncertainties and improve predictions of surface flux with the assimilation of FY3A-VIRR LST data.