The semiannual variation of transpolar arc incidence and its relationship to the Russell–McPherron effect

Earth’s aurora is a luminescent phenomenon generated by the interaction between magnetospheric precipitating particles and the upper atmosphere;it plays an important role in magnetosphere–ionosphere(M-I)coupling.The transpolar arc(TPA)is a discrete auroral arc distributed in the noon-midnight direction poleward of the auroral oval and connects the dayside to the nightside sectors of the auroral oval.Studying the seasonal variation of TPA events can help us better understand the long-term variation of the interaction between the solar wind,the magnetosphere,and M-I coupling.However,a statistical study of the seasonal variation of TPA incidence has not previously been carried out.In this paper,we have identified 532 TPA events from the IMAGE database(2000–2005)and the Polar database(1996–2002),and calculated the incidence of TPA events for different months.We find a semiannual variation in TPA incidence.Clear peaks in the incidence of TPAs occur in March and September;a less pronounced peak appears in November.We also examine seasonal variation in the northward interplanetary magnetic field(IMF)over the same time period.The intensity and occurrence rate of the northward IMF exhibit patterns similar to that of the TPA incidence.Having studied IMF Bz before TPA onset,we find that strong and steady northward IMF conditions are favorable for TPA formation.We suggest that the semiannual variation observed in TPA incidence may be related to the Russell–McPherron(R-M)effect due to the projection effect of the IMF By under northward IMF conditions.

Annual variation of adult survival of a south-temperate House Wren population in Argentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the south.Here,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival estimators.We found that the probability of adult survival decreased as the abundance of breeding adults increased.This density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.

Horizontal Distribution and Annual Variations of Fecal Coliform Bacteria in Luoyuan Bay

Fecal Coliform Bacteria （FCB） of marine waters was monitored in Luoyuan Bay from January, 2003 to December, 2005. The results showed that number of FCB in marine water samples ranged from no detection （ 〈2 cfu/100 mL） to 540 cfu/100 mL in Luoyuan Bay. Values of FCB during August to October were significantly higher than those during January to April during three year period. Monthly changes of FCB values at each year period were mainly due to monthly precipitation. In addition, compared with FCB values in difference sample sites, values of FCB in Bay-heed were significantly higher than those in middle of bay and Bay-mouth, Luoyuan Bay. However, values of FCB in Bay-mouth were significantly less than those in middle of bay. The ratios to the par of FCB in 2003, 2004, and 2005 years were 100%, 98.0%, and 97.9%, respectively. Therefore, we considered that the pollution of FCB of surface marine water in Luoyuan Bay was not serious.

Seasonal and inter-annual variations of the primary types of the Arctic sea-ice drifting patterns

Abstract Monthly mean sea ice motion vectors and monthly mean sea level pressure （SLP） for the period of 1979-2006 are investigated to understand the spatial and temporal changes of Arctic sea-ice drift. According to the distinct differences in monthly mean ice velocity field as well as in the distribution of SLP, there are four primary types in the Arctic Ocean： Beaufort Gyre＋Transpolar Drift, Anticyclonic Drift, Cyclonic Drift and Double Gyre Drift. These four types account for 81% of the total, and reveal distinct seasonal variations. The Cyclonic Drift with a large-scale anticlockwise ice motion pattern trends to prevail in summer while the Anticyclonic Drift with an opposite pattern trends to prevail in winter and spring. The prevailing seasons for the Beaufort Gyre＋Transpolar Drift are spring and autumn, while the Double Gyre Drift trends to prevail in winter, especially in Feb- ruary. The annual occurring times of the Anticyclonic Drift and the Cyclonic Drift are closely correlated with the yearly mean Arc- tic Oscillation （AO） index, with a correlation coefficient of -0.54 and 0.54 （both significant with the confident level of 99%）, re- spectively. When the AO index stays in a high positive （negative） condition, the sea-ice motion in the Arctic Ocean demonstrates a more anticlockwise （clockwise） drifting pattern as a whole. When the AO index stays in a neutral condition, the sea-ice motion becomes much more complicated and more transitional types trend to take place.

Seasonal and annual variations of marine sinking particulate flux during 1993 ~ 1996 in the central South China Sea

A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993 ~ 1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species （ Globigerinoides sacculifer , G. ruber , Globigerinita glutinata, Neogloboquadrina dutertrei ） and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution.

Estimation of annual variation of water vapor in the Arctic Ocean between 80°–87°N using shipborne GPS data based on kinematic precise point positioning

The measurement of atmospheric water vapor （WV） content and variability is important for meteorological and climatological research. A technique for the remote sensing of atmospheric WV content using ground-based Global Positioning System （GPS） has become available, which can routinely achieve accuracies for integrated WV content of 1-2 kg/m2. Some experimental work has shown that the accuracy of WV measurements from a moving platform is comparable to that of （static） land-based receivers. Extending this technique into the marine environment on a moving platform would be greatly beneficial for many aspects of meteorological research, such as the calibration of satellite data, investigation of the air-sea interface, as well as forecasting and climatological studies. In this study, kinematic precise point positioning has been developed to investigate WV in the Arctic Ocean （80°-87°N） and annual variations are obtained for 2008 and 2012 that are identical to those related to the enhanced greenhouse effect.

Annual Variation of Mineral Nutrition Elements Content in Macadamia integrifolia

[Objective] To investigate the annual variation of 9 mineral nutrition ele-ments content in Macadamia integrifolia leaves. [Method] Twenty 6-year-old ＆quot;Guire No. 1＆quot; healthy plants were selected. On the 15th of every month in 2011, 1 leaf in the second round from top-branch in 4 directions of the 20 trees was col ected. The content of 9 mineral elements of N, P, K, Ca, Mg, Zn, Cu, Fe and Mn were deter-mined. [Result] The results showed that the N, P, K content in leaves reached a peak in April, then N content decreased slowly, P content stayed stable, and K con-tent increased slightly; Ca, Fe content decreased in April to different degrees and then increased slowly. Mg content was consistent al year round, meanwhile Mn content decreased slightly. Cu and Zn content reached a peak in April, and then presented a rise-fal trend. [Conclusion] N, K, Ca, Mg should be supplemented in time in practice.

The distribution and inter-annual variation of water masses on the Bering Sea shelf in summer

On the basis of the CTD data obtained within the Bering Sea shelf by the Second to Sixth Chinese National Arctic Research Expedition in the summers of 2003, 2008, 2010, 2012 and 2014, the classification and interannual variation of water masses on the central Bering Sea shelf and the northern Bering Sea shelf are analyzed. The results indicate that there are both connection and difference between two regions in hydrological features. On the central Bering Sea shelf, there are mainly four types of water masses distribute orderly from the slope to the coast of Alaska： Bering Slope Current Water（BSCW）, MW（Mixed Water）, Bering Shelf Water（BSW） and Alaska Coastal Water（ACW）. In summer, BSW can be divided into Bering Shelf Surface Water（BSW_S） and Bering Shelf Cold Water（BSW_C）. On the northern Bering Sea shelf near the Bering Strait,it contains Anadyr Water（AW）, BSW and ACW from west to east. But the spatial-temporal features are also remarkable in each region. On the central shelf, the BSCW is saltiest and occupies the west of 177°W, which has the highest salinity in 2014. The BSW_C is the coldest water mass and warmest in 2014; the ACW is freshest and mainly occupies the east of 170°W, which has the highest temperature and salinity in 2012. On the northern Bering Sea shelf near the Bering Strait, the AW is saltiest with temperature decreasing sharply compared with BSCW on the central shelf. In the process of moving northward to the Bering Strait, the AW demonstrates a trend of eastward expansion. The ACW is freshest but saltier than the ACW on the central shelf,which is usually located above the BSW and is saltiest in 2014. The BSW distributes between the AW and the ACW and coldest in 2012, but the cold water of the BSW_C on the central shelf, whose temperature less than 0°C, does not exist on the northern shelf. Although there are so many changes, the respond to a climate change is synchronized in the both regions, which can be divided into the warm years（2003 and 2014） and cold years（2008, 2010 and 2012）. The year of 2014 may be a new beginning of warm period.

Effects of PHC on Water Quality of Jiaozhou Bay Ⅰ. Annual Variation of PHC Content

Based on investigation data on PHC in Jiaozhou Bay, China from 1979 to 1983, the monthly, seasonal and annual variations of PHC content in Jiaozhou Bay were studied. The results showed that from 1979 to 1983, Jiaozhou Bay was polluted by PHC seriously and then slightly in spring and summer, while Jiaozhou Bay was polluted by PHC slightly in autumn. During 1979 -1983, PHC content in the water body of Jiaozhou Bay decreased year by year, and it was close to the background value gradually. Moreover, the reduction was obvious in spring and summer but very slight in autumn. Therefore, the water quality of Jiaozhou Bay became better.

Annual variation rate of global sea－level rise and the prediction for the 21st century

An analytics method of predicting the annual variation rate (AVR) of global sea-level (GSL) is developed.Through the calculation by using the mean sea-level data collected from the tidal gauge stations over the world, a GSL rise of 0. 15～0. 16 cm/a is obtained. The predicted values of AVR of GSL for the 21st century are presented. The authors' results have been compared to those reported by other scientists at home and abroad. The method proposedhere is more convenient and precise.

Annual Variation of Local Photon Emissions’ Spectral Power within the mHz Range Overlaps with Seismic-Atmospheric Acoustic Oscillations

Spheroidal modes of seismic and acoustic oscillations in the atmosphere occur within the 2 to 7 mHz range with peak-to-peak variations in the order of 10–12 to 10–11 m·s–2. Previous research indicated the amplitudes for 230 s and 270 s periods peak during the summer months. In the present study the amplitudes of a reliably apparent 3 mHz increment from spectral analyses of minute-to-minute measurements of background photon emissions by a photomultiplier tube housed in a dark room were sampled for a one year period. The peak increase in the power of this increment was maximal during the summer months and overlapped conspicuously with the annual variation in fundamental spheroidal modes of seismic free oscillations. Quantitative estimates indicate that relative shifts in the order of 10–11 W/m2 for photon emissions may reflect the annual variation in coupled oscillations between the earth and atmosphere.

STUDY ON THE RELATIONSHIP BETWEEN THE DECADAL VARIATIONS OF ANNUALLY FIRST RAINY SEASON PRECIPITATION OF GUANGXI AND SEA SURFACE TEMPERATURE OF INDIAN OCEAN IN SOUTHERN HEMISPHERE

Decadal circulation differences between more and less rainfall periods in the annually first rainy season of Guangxi and their association with sea surface temperature (SST) of the austral Indian Ocean are investigated by using the NCEP/NCAR reanalysis data. The results are shown as follows. A pattern in which there is uniform change of the Guangxi precipitation shows a 20-year decadal oscillation and a 3-year interannual change. In contrast, a pattern of reversed-phase change between the north and the south of Guangxi has a 6-year interannual periodicity and quasi-biennial oscillation. In the period of more precipitation, the surface temperature in Eurasia is positively anomalous so as to lead to stronger low pressure systems on land and larger thermal contrast between land and ocean. Therefore, the air column is more unstable and ascending flows over Guangxi are intensified while the Hadley cell is weakened. Furthermore, the weaker western Pacific subtropical high and South Asia High, together with a stronger cross-equatorial flow, result in the transportation of more humidity and the appearance of more precipitation. The correlation analysis indicates that the Indian Ocean SST in Southern Hemisphere is closely associated with the variation of the seasonal precipitation of Guangxi on the decadal scale by influencing the Asian monsoon through the cross-equatorial flow.

Some Annual Variation Characteristics for the Northern Hemispheric Monthly Mean Precipitation Fields

By the utilization of monthly precipitation data from all stations in the Northern Hemisphere annexed to the 'World Survey of climatology, Vol. 1-15', the distributions of the maximum precipitation months (MPM), the annual relative precipitation (ARP) and the monthly relative precipitation (percent of annual) in January and July are respectively mapped. Moreover the distributions of intermonthly relative precipitation variabilities from January to December are plotted as well. From these figures, the precipitation in the Northern Hemisphere may be classified into three types(continental, oceanic and transitional types) and 17 regions. The precipitation regime may also be divided into two patterns, the global and regional patterns. The global pattern consists of planetary front system and ITCZ and its inter-monthly variation shows the north-and-south shift of the rain belt; the regional pattern consists of the sea-land monsoon and plateau monsoon regime, in which the inter-monthly variation of rain belt shows a east-and-wcst shift.

Electromagnetic response function for the semi-annual variations estimated by the single-station method using the night-time values of the geomagnetic fields

The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper.

Three-year Variations of Water, Energy and CO_2 Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China

Based on 3 years （2003-05） of the eddy covariance （EC） observations on degraded grassland and cropland surfaces in a semi-arid area of Tongyu （44°25′N, 122°52′E, 184 m a.s.1.）, Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated. The soil moisture in the thin soil layer （at 0.05, 0.10 and 0.20 m） clearly indicates the pronounced annual wet-dry cycle; the annual cycle is divided into the wet （growing season） and dry seasons （non-growing season）. During the growing season （from May to September）, the sensible and latent heat fluxes showed a linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux was always less than 50 W m^-2, while the available energy was dissipated as sensible, rather than latent heat flux. During the growing season in 2003-05, the daily average sensible and latent heat fluxes were larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2 than the degraded grassland ecosystem in the growing season in 2003-05. The total evapotranspiration on the cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland was almost the same as the total annual precipitation in the growing season. The soil moisture had a good correlation with the rainfall in the growing season. Precipitation in the growing season is an important factor on the water and carbon budget in the semi-arid area.

Research on runoff variations based on wavelet analysis and wavelet neural network model： A case study of the Heihe River drainage basin （1944-2005）

The Heihe River drainage basin is one of the endangered ecological regions of China. The shortage of water resources is the bottleneck, which constrains the sustainable development of the region. Many scholars in China have done researches concerning this problem. Based on previous researches, this paper analyzed characteristics, tendencies, and causes of annual runoff variations in the Yingluo Gorge （1944-2005） and the Zhengyi Gorge （1954-2005）, which are the boundaries of the upper reaches, the middle reaches, and the lower reaches of the Heihe River drainage basin, by wavelet analysis, wavelet neural network model, and GIS spatial analysis. The results show that： （1） annual runoff variations of the Yingluo Gorge have principal periods of 7 years and 25 years, and its increasing rate is 1.04 m^3/s.10y; （2） annual runoff variations of the Zhengyi Gorge have principal periods of 6 years and 27 years, and its decreasing rate is 2.25 m^3/s.10y; （3） prediction results show that： during 2006-2015, annual runoff variations of the Yingluo and Zhengyi gorges have ascending tendencies, and the increasing rates are respectively 2.04 m^3/s.10y and 1.61 m^3/s.10y; （4） the increase of annual runoff in the Yingluo Gorge has causal relationship with increased temperature and precipitation in the upper reaches, and the decrease of annual runoff in the Zhengyi Gorge in the past decades was mainly caused by the increased human consumption of water resources in the middle researches. The study results will provide scientific basis for making rational use and allocation schemes of water resources in the Heihe River drainage basin.

Trend and seasonal variations of atmospheric CH_4 in Beijing

The atmospheric CH\-4 in Beijing is still increasing, even though its increasing rate has significantly decreased from 1.76%/a during 1985—1989 to 0.50%/a during 1990—1997. The seasonal variation of CH\-4 concentration showed a double\|peak pattern, one peak appearing in winter and the other in summer. It is evident that the annually seasonal variations of atmospheric CH\-4 in Beijing are different. From 1986 to 1997, the atmospheric CH\-4 increased by 185 ppbv, 37% and 21% of which were due to the increase in winter and in summer, respectively. After 1993, the annually seasonal increasing rate of CH\-4 concentration in summer (due to emission from biogenic sources) is negative while the increasing rate in winter (due to emission from non\|biogenic sources) is positive about 25 ppbv/a. As a result, the increase of CH\-4 emission from non\|biogenic sources in winter is the major reason that caused the annually seasonal increasing rate from 1993 to 1997. The biogenic sources in Beijing are shrinking while the non\|biogenic ones (such as fossil fuel combustion) are enlarging.

Variations of electron density and temperature in ionosphere based on the DEMETER ISL data

Observations of the Langmuir Probe Instrument （ISL, Instrument Sonde de Langmuir） onboard the DEMETER satellite during four years from 2006 to 2009 were used to analyze the tempo-spatial variations of electron density （Ne） and temperature （Te） in the ionosphere. Twenty four research bins with each covering an area with 10° in longitude and 2° in latitude were selected to study the spatial distributions of Ne and Te. The results indicate that both Ne and Te have strong an- nual variations in the topside ionosphere at 660 krn altitude. The semiannual anomaly and equinoctial asymmetry which are usually well known as the features of F-layer also exist in the topside ionosphere at low- and mid-latitudes. The yearly varia- tion of No is opposite to the peak electron density of the F2-1ayer （NmF2） at higher latitudes in daytime and both are similar in nighttime. Also the yearly variations of Tc at low-latitude are contrary to that at 600 km in daytime and similar in nighttime An interesting feature of nighttime Te at low-latitude is an obvious annual variation in the northern hemisphere and semian- nual variation in the southern hemisphere. The yearly variations of Te in daytime have negative and positive correlation with Ne at mid- and high-latitudes, respectively. Both Nc and Te in the neighborhood bins at the same latitude have a high correlation. In ionospheric events analyzing, this information may help to understand the characteristics of the variation and to dis- tinguish the reliable abnormality from the normal background map.

Temporal-Spatial Variation of Surface Suspended Matter and Controlling Factors in the Inner Shelf of the East China Sea in Winter

Based on the observed surface suspended matter in the East China Sea in February 2007 and June 2015, an empirical model was established using L1 b's band 4 data to retrieve surface suspended matter from the Moderate Resolution Imagine Spectroradiometer Terra imagery. The squared correlation coefficient is 0.8358, and the root mean square error is 0.4285 mg L-1. The model reflects the distribution characteristics of surface suspended matter in the inner shelf of the East China Sea. In this paper, the satellite images of the study area were retrieved in January from 2001 to 2015, and the monthly distribution of surface suspended matter were obtained. The inter-annual distribution of the study area is similar, and the concentration of surface suspended matter is higher near the shore than offshore. A large amount of surface suspended matter is transported southeast under the influence of Zhejiang and Fujian coastal current and Taiwan warm current. Only a small amount of surface suspension can reach the Kuroshio area. The surface suspended matter concentration changes obviously near the estuary because of the effect of differences in the flux of the Yangtze River. Meanwhile, winter monsoon, temperature front, El Ni?o events, and other factors affect the distribution of surface suspended matter in 100 m isobath to coastal water but minimally influence the distribution in 100 m isobath to deep sea.

foF2 Seasonal Asymmetry Time Variation at Korhogo Station from 1992 to 2002

foF2 seasonal asymmetry is investigated at Korhogo station from 1992 to 2002. We show that equinoctial asymmetry is less pronounced and somwhere is absent trough out solar cycle phase. In general, the absence of equinoctial asymmetry may be due to the fact that in equinox and for each solar cycle phase, the asymmetry is due to Russell-McPherron mechanism. The solstice anomaly or annual anomaly is always observed throughout solar cycle phase. The minimum value of ΔfoF2 is inferior than −60% seen during all solar cycle phase at 0700 LT. This annual asymmetry may be due to interplanetary corpuscular radiation.