THE INTERACTION BETWEEN EDDY FLUX AND ZONAL AVERAGED FLOW IN“JUNE SUDDEN CHANGE”

In this paper,Eliassen-Palm theory and associated diagnostic method are used to discuss the dynamical mechanism of the interaction between eddy flux and zonal averaged flow in the sudden change of the general circulation in the Northern Hemisphere in early summer of 1982,which indicates that the northward jump of subtropic jet stream is closely related to the enhanced transport of mid-latitude eddy energy to the subtropic tro- popause.However,the direction of the transport is conditioned by the structure of zonal averaged flow.It is evident that the adjustment of zonal averaged flow responses quickly to the eddy transport during this episode. As regard to the suddenness of the change of circulation,the critical role is played by the eddy forcing,

Super Typhoon Hinnamnor(2022)with a Record-Breaking Lifespan over the Western North Pacific

Super Typhoon Hinnamnor(2022)was a rare and unique western North Pacific typhoon,and throughout its lifespan,it exhibited all of the major features that pose current challenges in typhoon research.Specifically,during different stages of its lifespan,it experienced a sudden change of track,underwent rapid intensification,interacted and merged with another vortex,expanded in size,underwent rapid weakening,produced a strong cold wake,exhibited eyewall replacement,and underwent extratropical transition.Therefore,a timely identification and review of these features of Hinnamnor(2022),as reported in this article,will help update and enrich the case sets for each of these scientific issues and provide a background for more in-depth mechanistic studies of typhoon track,intensity,and structural changes in the future.We also believe that Hinnamnor(2022)can serve as an excellent benchmark to quickly evaluate the overall performance of different numerical models in predicting typhoon’s track,intensity,and structural changes.

Abnormal Phenomena Recorded by Several Earthquake Precursor Observation Instruments Before the M_s 8.0 Wenchuan,Sichuan Earthquake

The paper introduces the anomalies observed by digital tiltmeter, cross-fault deformation meter, 4-component borehole strainmeter and geothermometer before May 12, 2008, Ms8.0 Wenchuan earthquake, Sichuan. The digital tiltmeter installed in the epicentral region in Shifang County recorded the tilt anomalies 15 days before the earthquake with variation amplitude of 3.7 times larger than the annual deviation of 2007. The cross-fault deformation meter installed at Zimakua station on the Xianshuihe-Anninghe fault zone detected displacement anomaly occurring since 2006 with the variation amplitude exceeding the cumulative value of the last ten years. Five borehole strainmeter stations in the Chongqing section of Three Gorges Reservoir area observed unconventional strain changes occurring in the period from May 1 through 12, 2008. Among them, the strainmeter at Wanzhou station recorded the great compression strain rate on the EW component at 14：00 o＇clock of May 10, and the anomaly amplitude was so large that the instrument output exceeded its dynamic range, corresponding to a level of -10^4 nanostrains. The geothermometers installed in Xi＇an, Chongqing and Xichang recorded the sudden temperature changes from November 2007 to January 2008 with the variation amplitudes several times larger than the ordinary deviation. The above phenomena and the criteria for distinguishing the anomalies from background fluctuations are discussed in this paper.

Aerodynamic characteristics of a high-speed train crossing the wake of a bridge tower from moving model experiments

In a strong crosswind,the wake of a bridge tower will lead to an abrupt change of the aerodynamic forces acting on a vehicle passing through it,which may result in problems related to the transportation safety.This study investigates the transient aerodynamic characteristics of a high-speed train moving in a truss girder bridge and passing by a bridge tower in a wind tunnel.The scaled ratio of the train,bridge,and tower are 1:30.Effects of various parameters such as the incoming wind speed,train speed,and yaw angle on the aerodynamic performance of the train were considered.Then the sudden change mechanism of aerodynamic loads on the train when it crosses over the tower was further discussed.The results show that the bridge tower has an apparent shielding effect on the train passing through it,with the influencing width being larger than the width of the tower.The train speed is the main factor affecting the influencing width of aerodynamic coefficients,and the mutation amplitude is mainly related to the yaw angle obtained by changing the incoming wind speed or train speed.The vehicle movement introduces an asymmetry of loading on the train in the process of approaching and leaving the wake of the bridge tower,which should not be neglected.

Changing Characteristics of Temperature in Longnan City in Recent 54 Years

Based on the observation data of temperature in Chengxian meteorological station（ the climate representative station of Longnan City,Gansu Province） during 1961-2014,the annual,seasonal and monthly changes of temperature were analyzed,and the abrupt changes in relevant variables were tested using the cumulative anomaly method. The results showed that annual average temperature in Chengxian County increased by 0. 138 ℃/10 a in the past 54 years. There was an obvious sudden change in annual average temperature around 1996. The annual average temperature showed a downward trend before 1996 and an upward trend after 1996. Average temperature in spring,summer,autumn and winter increased by 0. 113,0. 028,0. 157 and 0. 259 ℃/10 a respectively. The fluctuation of average temperature in spring and winter was the largest,followed by summer,while the fluctuation was the smallest in autumn. There were certain differences between various seasons in terms of the years with sudden changes in average temperature,which was not consistent with the years with the sudden changes in annual average temperature. The changing rate of monthly average temperature was the largest in February（ up to 0. 412 ℃/10 a）,followed by March,April and November,but it was the smallest in May（ only 0. 005 ℃/10 a）. The maximum of monthly average temperature appeared mostly in the 21 stcentury,while the minimum appeared in the 20 thcentury.

Analysis on the Variation Characteristics of Temperature in Wengyuan from 1961 to 2018

Based on the monthly average temperature data from Wengyuan national meteorological observation station in Guangdong Province from 1961 to 2018, statistical methods were used for the trend analysis, mutation detection and wavelet analysis of annual average temperature and seasonal average temperature from 1961 to 2018. The results show that the annual, summer, autumn and winter average temperature in Wengyuan all showed a warming trend from 1961 to 2018, among which winter average temperature contributed the most to the increase of annual average temperature, and the increasing trend of average temperature in spring did not pass the significance test. The annual, summer, autumn and winter average temperature in Wengyuan changed significantly in 1994, 1981, 1996 and 1990, respectively. Wavelet analysis shows that the annual average temperature in Wengyuan had periodic oscillations on the time scales of 12-13, 24-25 and 6 years.

CLIMATIC ABRUPT CHANGE IN THE NORTHERN HEMISPHERE FOR 1920s AND 1950s

In recent years,a large number of papers on the climatic sudden change have been presented.From the viewpoint of climatic sudden change,two methods of studying climatic sudden change are applied in this paper.The Northern Hemi- sphere land temperature(NHLT)during 1851—1984,China temperature(CT)during 1873—1990 and the Northern Hemisphere sea-level pressure(NHSLP)at each grid point during 1899—1987 are analyzed by the moving T-test.The results show that there exist two climatic sudden changes in the 1920s and the 1950s during the past 100 years,and then features of circulation for the two sudden changes are discussed by the NHSLP data.