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Science China(Technological Sciences) 2019年第7期62卷 1182-1190页

作者： PRIYADARSHI Shishir ZHANG Qing-He WANG Yong Shandong Provincial Key laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong University

mid-latitude ionospheric scintillation has been studied in very poor proportion as compared to the equatorial and high latitude ionospheric scintillation. mid-latitude ionospheric scintillations are often associated with either day time photo-ionization or due to the storm enhanced density. Using the phase screen model and the wave propagation theory in random media, we have identified the orientation of the ionospheric irregularities over Weihai with the local geomagnetic field. Amplitude and phase scintillation data observed using global positioning system(GPS) scintillation receiver deployed at the mid-latitude observation station Weihai, have been used along with K-index derived from the horizontal magnetic field component of the local magnetometer. The proposed model uses the scintillation indices relationship with the local K-index. We identified the scintillation dependence over local K-index during geomagnetic quiet and disturbed condition. This dependence coefficient is used on the real scintillation data for modeling. The presented scintillation model has been validated by comparing it to the real observations. The co-relation coefficient is more than 90% during the disturbed as well as quiet geomagnetic conditions.

关键词： mid-latitude ionosphere scintillation GPS global navigation satellite systems (GNSS)

QUASI-RESONANCE OF BAROTROPIC ATMOSPHERIC WAVE MOTION AND mid-latitude LOW-FREQUENCY OSCILLATION

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Science China Chemistry 1992年第7期35卷 847-858页

作者：陆维松 Nanjing Institute of Meteorology Nanjing 210044 PRC

It is proved, based on the quasi--geostropic barotropic vortex equation and the quasi-resonance conditions K_1+ K_2+ K_3=0 and ω_1 +ω_1 +ω_3 =Δω, that the analytic solution ofthe 3--wave amplitude of quasi--resonance is an elliptical function. The approximate expressionfor the periodic variation of wave energy is thus obtained under certain conditions. Boththe approximate expression and numerical calculation indicate that the period of energyvariation approaches the period 1/Δω corresponding to the quasi--resonance frequency biasΔω itself. When Δω～(0.1--0.025)o(ω_j), the energy variation period is 12---46 days andwhen Δω=0, it is 25--568 days. Therefore, the occurrence of frequency bias Δω is probablya new important mechanism for the formation of mid-latitude low--frequency *** also accounts for the result of the numerical test Egger (1978) did on blocking causedby the resonance of two topographic stationary waves and one free slow wave.

关键词： quasi-resonance mid-latitude low-frequency oscillation blocking

Atmospheric eddy anomalies associated with the wintertime North Pacific subtropical front strength and their influences on the seasonal-mean atmosphere

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Science China Earth Sciences 2016年第10期59卷 2022-2036页

作者： WANG LiYing HU HaiBo YANG XunQun REN XueJuan CMA-NJU Joint Laboratory for Climate Prediction Studies Instituted for Climate and Global Change Research School of Atmospheric Science Nanjing University

This study investigates transient eddy activity anomalies in the mid-latitude upper troposphere associated with intensity variability of the wintertime North Pacific subtropical front. Our results show that the meridional gradient of air temperature and baroclinic instability in the mid-latitude atmosphere become stronger as the subtropical front intensifies, and the mid-latitude westerly jet accelerates with barotropic structure. We further divide the mid-latitude atmospheric eddy activities into high-(2–7 days) and low-frequency(10–90 days) eddy activities according to their life periods. We find that, when the oceanic subtropical front intensifies, the high-frequency atmospheric eddy activity in the mid-latitudes strengthens while the low-frequency eddy activity weakens. The stronger high-frequency eddy activity tends to moderate the air temperature gradient and baroclinicity in the mid-latitudes. High-frequency eddy anomalies accelerate the westerly jet on the northern side and downstream of the westerly jet, and enhance the jet with equivalent barotropic structure. In contrast, the weaker low-frequency eddy activity has a negative contribution to zonal wind speed tendency and attenuates the zonal homogenization of the jet. The anomalous thermodynamic forcing of the low-frequency eddy activity helps maintain the meridional gradient of air temperature in the mid-troposphere.

关键词： North Pacific subtropical front Frequency Eddy activity mid-latitude Ocean-Atmosphere interaction

Late Holocene hydroclimatic variations and possible forcing mechanisms over the eastern Central Asia

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Science China Earth Sciences 2019年第8期62卷 1288-1301页

作者： Jianghu LAN Hai XU Keke YU Enguo SHENG Kangen ZHOU Tianli WANG YuANDa YE Dongna YAN Huixian WU Peng CHENG Waili ABULIEZI Liangcheng TAN State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an710061China Institute of Surface-Earth System Science Tianjin UniversityTianjin300072China Key Laboratory of Disaster Monitoring and Mechanism Simulating of Shaanxi Province Baoji University of Arts and SciencesBaoji721013ShaanxiChina State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang550002China University of Chinese Academy of Sciences Beijing100049China Administrative Committee of Lake Sayram Bozhou833400China Institute of Global Environmental Change Xi’an Jiaotong UniversityXi’an710049China

Hydroclimatic variations over the eastern Central Asia are highly sensitive to changes in hemispheric-scale atmospheric circulation systems. To fully understand the long-term variability and relationship between hydroclimate and atmospheric circulation system, we present a high-resolution lascustrine record of late Holocene hydroclimate from Lake Sayram, Central Tianshan Mountains, China, based on the total organic carbon, total nitrogen, and carbonate contents, carbon/nitrogen ratios, and grain size. Our results reveal four periods of substantially increased precipitation at the interval of 4000–3780, 3590–3210, 2800–2160, and 890–280 cal yr BP, and one period of slightly increased precipitation from 1700–1370 cal yr BP. These wetter periods broadly coincide with those identified in other records from the mid-latitude Westerlies-dominated eastern Central Asia, including the northern Tibetan Plateau. As such, a similar hydroclimatic pattern existed over this entire region during the late Holocene. Based on a close similarity of our record with reconstruction of North Atlantic Oscillation indices and solar irradiance, we propose that decreased solar irradiance and southern migration of the entire circum-North Atlantic circulation system, particularly the main pathway of the mid-latitude Westerlies, significantly influenced hydroclimate in eastern Central Asia during the late Holocene. Finally, the inferred precipitation at Lake Sayram has increased markedly over the past 100 years, although this potential future changes in hydroclimate in Central Asia need for further investigation.

关键词： Lake Sayram Hydroclimatic variation Late Holocene mid-latitude Westerlies North Atlantic Oscillation index

Spatio-temporal variations of Arctic amplification and their linkage with the Arctic oscillation

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Acta Oceanologica Sinica 2017年第8期36卷 42-51页

作者： WANG Yanshuo HUANG Fei FAN Tingting Physical Oceanography Laboratory/CIMST Ocean University of ChinaQingdao 266100China Qingdao National Laboratory for Marine Science and Technology Qingdao 266200China Ningbo Collabrative Innovation Center of Nonlinear Harzard System of Ocean and Atmosphere Ningbo UniversityNingbo 315211China

The Arctic near-surface air temperatures are increasing more than twice as fast as the global average-a feature known as Arctic amplification （AA）. A modified AA index is constructed in this paper to emphasize the contrast of warming rate between polar and mid-latitude regions, as well as the spatial and temporal characteristics of AA and their influence on atmospheric circulation over the Northern Hemisphere. Results show that AA has a pronounced annual cycle. The positive or negative phase activities are the strongest in autumn and winter, the weakest in summer. After experiencing a remarkable decadal shift from negative to positive phase in the early global warming hiatus period, the AA has entered into a state of being enlarged continuously, and the decadal regime shift of AA in about 2002 is affected mainly by decadal shift in autumn. In terms of spatial distribution, AA has maximum warming near the surface in almost all seasons except in summer. Poleward of 20~N, AA in autumn has a significant influence on the atmospheric circulation in the following winter. The reason may be that the autumn AA increases the amplitude of planetary waves, slows the wave speeds and weakens upper-level zonal winds through the thermal wind relation, thus influencing surface air temperature in the following winter. The AA correlates to negative phase of the Arctic oscillation （AO） and leads AO by 0-3 months within the period 1979-2002. However, weaker relationship between them is indistinctive after the decadal shift of AA.

关键词： Arctic amplification Arctic oscillation decadal shift mid-latitude

Characteristics and spatial distribution of strong warming events in the central Arctic(2000-2019)

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Advances in Polar Science 2021年第2期32卷 78-95页

作者： ZHANG Zelu ZHAO Jinping BIAN Lingen College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China Chinese Academy of Meteorological Sciences Beijing 100081China

Arctic amplification in the context of global warming has received considerable attention,and mechanisms such as ice-albedo feedback and extratropical cyclone activity have been proposed to explain such abnormal *** 2000,several short-term episodes of significant temperature rise have been observed in the Arctic;however,long-duration warming events in the central Arctic are less common and lack comprehensive *** studies identified that amplified Rossbywaves could connect Arctic warming with extreme weather events in mid-latitude regions,and thus the recent increase in the frequency of mid-latitude extreme weather is also a subject of intensive *** consideration of temperature anomalies,this study defined a continuous warming process as a warming event and selected strong warming events based on *** of National Centers for Environmental Prediction Reanalysis-2 surface air temperature data found that nine strong warming events occurred during 2000-2019,which could be categorized into three types based on the area of *** study also investigated the relation between strong warming events and sea ice concentration reduction,sudden stratospheric warming,and extratropical cyclone *** full consideration and comparison,we believe that strong warming events in the central Arctic are induced primarily by continuous transport of warm air from mid-latitude ocean areas.

关键词： Arctic amplification warming event mid-latitude extreme weather warm air