Anti-phase Relation Research Articles

Measurement of the transmission phase of an electron in a quantum two-path interferometer

A quantum two-path interferometer allows for direct measurement of the transmission phase shift of an electron, providing useful information on coherent scattering problems. In mesoscopic systems, however, the two-path interference is easily smeared by contributions from other paths, and this makes it difficult to observe the true transmission phase shift. To eliminate this problem, multi-terminal Aharonov-Bohm (AB) interferometers have been used to derive the phase shift by assuming that the relative phase shift of the electrons between the two paths is simply obtained when a smooth shift of the AB oscillations is observed. Nevertheless, the phase shifts using such a criterion have sometimes been inconsistent with theory. On the other hand, we have used an AB ring contacted to tunnel-coupled wires and acquired the phase shift consistent with theory when the two output currents through the coupled wires oscillate with well-defined anti-phase. Here, we investigate thoroughly these two criteria used to ensure a reliable phase measurement, the anti-phase relation of the two output currents, and the smooth phase shift in the AB oscillation. We confirm that the well-defined anti-phase relation ensures a correct phase measurement with a quantum two-path interference. In contrast, we find that even in a situation where the anti-phase relation is less well-defined, the smooth phase shift in the AB oscillation can still occur but does not give the correct transmission phase due to contributions from multiple paths. This indicates that the phase relation of the two output currents in our interferometer gives a good criterion for the measurement of the true transmission phase, while the smooth phase shift in the AB oscillation itself does not.

ON THE VARIATION OF SOLAR RADIUS IN ROTATION CYCLES

The Date Compensated Discrete Fourier Transform and CLEANest algorithm are used to study the temporal variations of the solar radius observed at Rio de Janeiro Observatory from 1998 March 2 to 2009 November 6. The CLEANest spectra show several significant periodicities around 400, 312, 93.5, 86.2, 79.4, 70.9, 53.2, and 26.3 days. Then, combining the data on the daily solar radius measured at Calern Observatory and Rio de Janeiro Observatory and the corresponding daily sunspot areas, we study the short-term periodicity of the solar radius and the role of magnetic field in the variation of the solar radius. The rotation period of the daily solar radius is determined to be statistically significant. Moreover, its temporal evolution is anti-phase with that of sunspot activity, and it is found anti-phase with solar activity. Generally, the stronger solar activity is, the more obvious is the anti-phase relation of radius with solar activity. This indicates that strong magnetic fields have a greater inhibitive effect than weak magnetic fields on the variation of the radius.

Correlation between solar activity and the local temperature of Antarctica during the past 11,000 years

The solar impact on the Earth's climate change is a long topic with intense debates. Based on the reconstructed data of solar sunspot number (SSN), the local temperature in Vostok (T), and the atmospheric CO2 concentration data of Dome Concordia, we investigate the periodicities of solar activity, the atmospheric CO2 and local temperature in the inland Antarctica as well as their correlations during the past 11,000 years before AD 1895. We find that the variations of SSN and T have some common periodicities, such as the 208 year (yr), 521yr, and ~1000yr cycles. The correlations between SSN and T are strong for some intermittent periodicities. However, the wavelet analysis demonstrates that the relative phase relations between them usually do not hold stable except for the millennium-cycle component. The millennial variation of SSN leads that of T by 30–40 years, and the anti-phase relation between them keeps stable nearly over the whole 11,000 years of the past. As a contrast, the correlations between CO2 and T are neither strong nor stable. These results indicate that solar activity might have potential influences on the long-term change of Vostok's local climate during the past 11,000 years before modern industry.

South Tropical Atlantic anti-phase response to Holocene Bond Events

Records of the climatic impacts of the North Atlantic Bond cycles over the subtropical Southern Hemisphere remain scarce, and their mechanism is a topic of active discussion. We present here an alkenone-based reconstructed sea surface temperature (SST) of a sediment core retrieved from the Brazilian Southwestern Tropical Atlantic (SWTA), Rio de Janeiro, together with a sediment SST record from the Cariaco Basin. The sediment cores span the period 2,100B.P. – 11,100B.P. Morlet-wavelet analysis detected marked periodic signals of ~0.8, ~1.7 and ~2.2kyr, very similar and with comparable phases to the hematite-stained-grain time series from the Northern North Atlantic in which the cyclic pattern was recognized as Bond cycles. Our result corroborates the modeled surface ocean anti-phase thermal relation between the North and the South Atlantic. We attribute this behavior to the slowing of the Atlantic Meridional Overturning Circulation. The relative SST warming at Rio de Janeiro and the relative cooling at Cariaco were comparatively more pronounced during the early Holocene (from 11 to 5kyr B.P.) than in more recent time.

Glucose-induced inhibition of insulin secretion

Increase in glucose is known to elevate the concentration of cytoplasmic Ca(2+) ([Ca(2+) ]i ) in pancreatic β-cells and stimulate insulin secretion. However, rise of glucose can also lower [Ca(2+) ]i and inhibit insulin release. In the present review, we examine the mechanisms for this inhibition and highlight its importance for the healthy β-cell and the development of diabetes. It is possible to distinguish between 60 and 90 s of prompt inhibition and the late inhibition seen after the first-phase peak of insulin release. The introductory inhibition is characteristic of the healthy β-cell and mediated by sequestration of [Ca(2+) ]i in the endoplasmic reticulum. This inhibition is easily seen in studies of isolated islets but too brief to be detected in a conventional intravenous glucose tolerance test. Coupled to simultaneous rise of glucagon, the introductory suppression of insulin release is the starting point for the antiphase relation between the subsequent insulin and glucagon pulses. Another effect of the initial suppression is to increase the pool of readily releasable granules responsible for the first-phase release of insulin. The presence of late inhibition of insulin release is an indicator of β-cell dysfunction. Patients with type 2 diabetes often respond to intravenous bolus injection of glucose with 5-10 min of late suppression of circulating insulin.

Baroclinic M2 tidal circulation in Algeciras Bay and its implications for the water exchange with the Strait of Gibraltar: Observational and 3-D model results

[1] The M2 tidal circulation in Algeciras Bay (Strait of Gibraltar) is analyzed using a 3-D, nonlinear, baroclinic, hydrodynamic model, in conjunction with observed data series. Results show the influence of the density stratification on the vertical structure of the M2 currents in Algeciras Bay, although its tidal dynamics shows major differences with respect to the Strait of Gibraltar. Whereas the M2 currents in the Strait present mainly barotropic behavior, the baroclinic effects prevail in Algeciras Bay. A notable finding is the presence of a tidal M2 counter-current system between the upper Atlantic and the lower Mediterranean water layers within the Bay, with amplitudes of up to 25 cm s−1. The interface between the two layers oscillates in antiphase relation with respect to the free-surface elevation, with amplitudes of almost 20 m. The presence of the submarine Algeciras Canyon was found to be determinant in the three-dimensional structure of tidal currents within the Bay, strengthening the baroclinic tidal regime of currents. This situation has quantitative consequences for the flow-exchange processes between Algeciras Bay and the outer Strait, with rates 20 times higher than those obtained when considering only the barotropic behavior, as well as inflow/outflow lateral recirculation volumes during half a tidal cycle that account for more than 20% of the net accumulated volume. This flow-exchange system was found to be affected by the nonlinear interaction processes between the first baroclinic period of resonance of Algeciras Bay and the M2 tide.

A dynamical system perspective to understanding badminton singles game play

By altering the task constraints of cooperative and competitive game contexts in badminton, insights can be obtained from a dynamical systems perspective to investigate the underlying processes that results in either a gradual shift or transition of playing patterns. Positional data of three pairs of skilled female badminton players (average age 20.5±1.38years) were captured and analyzed. Local correlation coefficient, which provides information on the relationship of players’ displacement data, between each pair of players was computed for angle and distance from base position. Speed scalar product was in turn established from speed vectors of the players. The results revealed two patterns of playing behaviors (i.e., in-phase and anti-phase patterns) for movement displacement. Anti-phase relation was the dominant coupling pattern for speed scalar relationships among the pairs of players. Speed scalar product, as a collective variable, was different between cooperative and competitive plays with a greater variability in amplitude seen in competitive plays leading to a winning point. The findings from this study provide evidence for increasing stroke variability to perturb existing stable patterns of play and highlights the potential for speed scalar product to be a collective variable to distinguish different patterns of play (e.g., cooperative and competitive).

Maintenance of the Upright Posture in Humans upon Disturbance of Stability of the Visually Perceived Environment: Effect of an Instruction for Controlling Body Sway

We examined the maintenance of the upright posture under conditions of immersion of the tested subject in a 3D virtual visual environment, VVE. The latter consisted of two plans, the foreground looked like a window of the room, while the background was a fragment of the urban landscape. The software used allowed us to correlate body sway within the sagittal plane with shifts of the VVE foreground doing the latter mobile. The linkage in the course of testing could be either antiphase (APh) or synphase (SPh); the background always remained immobile. Each experiment was conventionally divided into two parts. In the first part, the subjects were not informed that body sways in some trials can be linked with shifts of the visual environment and were proposed to look at some object within the stable background. In the second part, the subjects were preliminarily informed of the existence of such a linkage and proposed to minimize body sways within the sagittal plane by tracking shifts of the foreground with respect to some, selected preliminarily, object within the background. Trials with a linkage between body sways and VVE shifts were altered by trials with standing of the subject facing an absolutely immobile visual pattern (IVP) and trials with the eyes closed (EC). The impact of visual control on the postural maintenance was estimated according to changes in the amplitude and frequency characteristics of two variables; i) shifts of the vertical projection of the center of gravity (CG) of the body and ii) difference between the position of the center of feet pressure (CFP) and CG projection. Changes in the latter were considered the main controlled variable in the postural maintenance, while the CFP-CG was interpreted as a variable containing information on changes in the resulting muscle/joint stiffness in the ankle joints related to activation of the shin muscles. The analysis of CG and CFP-CG oscillations demonstrated clear dependence of their spectra on the direction of linkage between body sways and oscillations of the foreground and on the instruction obtained by the subjects. In the first group of tests, RMSs of the spectra of oscillations of both variables at the SPh linkage were found to be within the same range as in standing with the EC, while at the APh linkage these oscillations were closer to the range typical of IVP conditions. In the second group of tests, the RMS of the spectra calculated for both variables were qualitatively different. In the case of APh relations between body sways and foreground shifts, these values were smaller than values in standing at IVP, while under SPh conditions they were smaller than those typical of standing with the EC. Introduction of the instruction of the second test group was also reflected in changes of the parameters of the CFP-CG variable. At the APh relation, the RMSs of the spectra for this variable decreased somewhat, and their median frequency increased significantly. The data obtained allow us to hypothesize that the improvement of stability standing after introduction of the instruction specifying visual control and concentrating the latter on one direction of body sway results from more active using of visual feedback under conditions of perception of the VVE unstable foreground. This should be considered additional proof in favor of effective involvement of vision in postural control upon disturbances in stability of the external environment.

Slow magnetosonic waves detected in reconnection diffusion region in the Earth's magnetotail

We studied the ULF waves with a period of 30 s in the ion diffusion region of reconnection observed by Cluster satellites on 21 August 2002. The fast convective tailward ion flow accompanied with a large southward magnetic field component, a strong Hall magnetic field, and a Hall electric field demonstrates that the Cluster satellites are located in the ion diffusion region of reconnection. The analyses of wave properties using minimum variance analysis and timing method indicate that this wave is an obliquely propagating slow magnetosonic wave which is characterized by the anti phase relation between the magnitude of the magnetic field and the ion number density and by a propagation angle of around 130° with respect to the ambient magnetic field. This wave is generated by periodic magnetic reconnection. The periodic oscillations in the By and Bx components are driven by the periodic Hall current system, while the oscillation in the Bz component is driven by quasiperiodic convective tailward ion flows. The slow magnetosonic wave significantly influences the frequency of whistler waves and low hybrid waves excited by magnetic reconnection by changing the magnitude of the local magnetic field and subsequently the electron cyclotron frequency.

Spatial and temporal variability of water discharge in the Yellow River Basin over the past 60 years

Water discharge data of the Yellow River over the past 60 years was analyzed using the continuous wavelet transform (CWT) and Mann-Kendall (MK) test methods to identify spatial and temporal variation patterns. Potential connections between water discharge in the Yellow River Basin and El Nino/Southern Oscillation (ENSO) were also examined by the cross wavelet and wavelet coherence methods. CWT results show that the periodic oscilla- tions in water discharges had occurred at the temporal scales of 1-, 2- to 4-, 6- to 8- and 10- to 22-year. It was also found that at the annual timescale (1-year) the phase relations be- tween water discharge and ENSO were indistinct probably due to the strong influence by human disturbances. However, over the longer time scales, the phase relation becomes much clearer with an anti-phase relation being found mainly at inter-annual scale (2- to 8-year) and in-phase relation at decadal scale (16- to 22-year). According to the MK test results water discharge at most stations except Tangnaihai have decreased significantly and the abrupt change occurred in the mid-1980s or the early 1990s. The changes in water discharge were found to be influenced by both climate changes and human activities. Before 1970 the change in water discharge was positively related to precipitation variations in the river basin, but after 1970 the decrease in water discharge has been largely caused by various human activities including constructions of reservoirs, water abstraction and water-soil conservation with water abstraction being the main cause.

Binary-induced magnetic activity?

We present a first and detailed study of the bright and active K0IV-III star HD 123351. The star is found to be a single-lined spectroscopic binary with a period of 147.8919+-0.0003 days and a large eccentricity of e=0.8086+-0.0001. The rms of the orbital solution is just 47 m/s, making it the most precise orbit ever obtained for an active binary system. The rotation period is constrained from long-term photometry to be 58.32+-0.01 days. It shows that HD 123351 is a very asynchronous rotator, rotating five times slower than the expected pseudo-synchronous value. Two spotted regions persisted throughout the 12 years of our observations. Four years of Halpha, CaII H&K and HeI D3 monitoring identifies the same main periodicity as the photometry but dynamic spectra also indicate that there is an intermittent dependence on the orbital period, in particular for Ca ii H&K in 2008. Line-profile inversions of a pair of Zeeman sensitive/insensitive iron lines yield an average surface magnetic-flux density of 542+-72 G. The time series for 2008 is modulated by the stellar rotation as well as the orbital motion, such that the magnetic flux is generally weaker during times of periastron and that the chromospheric emissions vary in anti-phase with the magnetic flux. We also identify a broad and asymmetric lithium line profile and measure an abundance of log n(Li) = 1.70+-0.05. The star's position in the H-R diagram indicates a mass of 1.2+-0.1 Msun and an age of 6-7 Gyr. We interpret the anti-phase relation of the magnetic flux with the chromospheric emissions as evidence that there are two magnetic fields present at the same time, a localized surface magnetic field associated with spots and a global field that is oriented towards the (low-mass) secondary component.

Modulated Rashba interaction in a quantum wire: Spin and charge dynamics

It was recently shown that a spatially modulated Rashba spin-orbit coupling in a quantum wire drives a transition from a metallic to an insulating state when the wave number of the modulation becomes commensurate with the Fermi wave length of the electrons in the wire. It was suggested that the effect may be put to practical use in a future spin transistor design. In the present article we revisit the problem and present a detailed analysis of the underlying physics. First, we explore how the build-up of charge density wave correlations in the quantum wire due to the periodic gate configuration that produces the Rashba modulation influences the transition to the insulating state. The interplay between the modulations of the charge density and that of the spin-orbit coupling turns out to be quite subtle: Depending on the relative phase between the two modulations, the joint action of the Rashba interaction and charge density wave correlations may either enhance or reduce the Rashba current blockade effect. Secondly, we inquire about the role of the Dresselhaus spin-orbit coupling that is generically present in a quantum wire embedded in semiconductor heterostructure. While the Dresselhaus coupling is found to work against the current blockade of the insulating state, the effect is small in most materials. Using an effective field theory approach, we also carry out an analysis of effects from electron- electron interactions, and show how the single-particle gap in the insulating state can be extracted from the more easily accessible collective charge and spin excitation thresholds. The smallness of the single-particle gap together with the anti-phase relation between the Rashba and chemical potential modulations pose serious difficulties for realizing a Rashba-controlled current switch in an InAs-based device. Some alternative designs are discussed.

Complex transitions to synchronization in delay-coupled networks of logistic maps

A network of delay-coupled logistic maps exhibits two different synchronization regimes, depending on the distribution of the coupling delay times. When the delays are homogeneous throughout the network, the network synchronizes to a time-dependent state [F.M. Atay, J. Jost, A. Wende, Phys. Rev. Lett. 92, 144101 (2004)], which may be periodic or chaotic depending on the delay; when the delays are sufficiently heterogeneous, the synchronization proceeds to a steady-state, which is unstable for the uncoupled map [C. Masoller, A.C. Marti, Phys. Rev. Lett. 94, 134102 (2005)]. Here we characterize the transition from time-dependent to steady-state synchronization as the width of the delay distribution increases. We also compare the two transitions to synchronization as the coupling strength increases. We use transition probabilities calculated via symbolic analysis and ordinal patterns. We find that, as the coupling strength increases, before the onset of steady-state synchronization the network splits into two clusters which are in anti-phase relation with each other. On the other hand, with increasing delay heterogeneity, no cluster formation is seen at the onset of steady-state synchronization; however, a rather complex unsynchronized state is detected, revealed by a diversity of transition probabilities in the network nodes.

On the low-frequency phase relation between the Denmark Strait and the Faroe-Bank Channel overflows

Numerical simulations of the Atlantic and Arctic Oceans using an ocean-sea ice model are analysed with respect to interannual-to-decadal variability (1948–2008) of the dense water overflows east and west of Iceland. Besides the good agreement between observed and simulated Denmark Strait and Faroe-Bank Channel overflows, the model shows an antiphase relation between both transports at time scales of 3–10 yr. The analysis of wind stress curl over the Nordic Seas suggests that the phase relation is locally forced. The main mode of atmospheric variability in the Atlantic reinforces the dense overflow west of Iceland during positive phases of the North Atlantic Oscillation (NAO) and decreases it during negative phases. East of Iceland the overflow is decreased during positive phases of the NAO and increased during negative phases. After the mid-1990s, the antiphase relation is less clear due to a reduction of wind stress curl variance and a change in the production of dense water in the Nordic Seas. In that period, the Norwegian Sea experienced a reduction of its cyclonicity, leading to the export of a surplus of dense water across the Faroe-Shetland Channel. The forcing of the gyre variability is attributed to large-scale wind stress curl changes and to shifts of convection regimes linked to Arctic-Nordic Seas dense water exchange modifications at Fram Strait. Simulated sea surface height variability is highly correlated with the dense water volume in the Greenland and Norwegian Seas gyres, implying that altimetric measurements are good indicators of dense water content in the Nordic Seas and therefore provide a potential for monitoring the reservoirs and explain/anticipate changes in the overflows.

Features of SAO in ozone and temperature over tropical stratosphere by wavelet analysis

Spatiotemporal variation of Semi-Annual Oscillation (SAO) in temperature and ozone over the tropical–subtropical belts (40° N–40° S) was studied using Microwave Limb Sounder data for the period 1992–1999. Wavelet analysis followed by cross-wavelet analysis was performed to study interannual variations in amplitude and phases of SAO and to determine the definite relationship between them. Latitude–height cross-sections of amplitudes of temperature and ozone SAO exhibit a peak near the Equator. The peak in amplitude of temperature SAO is at a higher altitude (ca 2 hPa) than that in ozone SAO (ca 6 hPa). The peak in amplitude of ozone SAO is almost symmetrical around the Equator but, in temperature SAO, it is asymmetrical around the Equator. The phase structure reveals that the temperature SAO descends faster than the ozone SAO. Cross-wavelet analysis shows an antiphase relation between the amplitude of the temperature and ozone SAO in the upper stratospheric region, whereas an in-phase relation exists in the lower stratospheric region.

On the low-frequency phase relation between the Denmark Strait and the Faroe-Bank Channel overflows

Numerical simulations of the Atlantic and Arctic Oceans using an ocean-sea ice model are analysed with respect to interannual-to-decadal variability (1948–2008) of the dense water overflows east and west of Iceland. Besides the good agreement between observed and simulated Denmark Strait and Faroe-Bank Channel overflows, the model shows an antiphase relation between both transports at time scales of 3–10 yr. The analysis of wind stress curl over the Nordic Seas suggests that the phase relation is locally forced. The main mode of atmospheric variability in the Atlantic reinforces the dense overflow west of Iceland during positive phases of the North Atlantic Oscillation (NAO) and decreases it during negative phases. East of Iceland the overflow is decreased during positive phases of the NAO and increased during negative phases. After the mid-1990s, the antiphase relation is less clear due to a reduction of wind stress curl variance and a change in the production of dense water in the Nordic Seas. In that period, the Norwegian Sea experienced a reduction of its cyclonicity, leading to the export of a surplus of dense water across the Faroe-Shetland Channel. The forcing of the gyre variability is attributed to large-scale wind stress curl changes and to shifts of convection regimes linked to Arctic-Nordic Seas dense water exchange modifications at Fram Strait. Simulated sea surface height variability is highly correlated with the dense water volume in the Greenland and Norwegian Seas gyres, implying that altimetric measurements are good indicators of dense water content in the Nordic Seas and therefore provide a potential for monitoring the reservoirs and explain/anticipate changes in the overflows.

Quasi-biennial oscillation in ozone and temperature over tropics

Spatiotemporal variations of the quasi-biennial oscillation (QBO) in temperature and ozone over the tropical–subtropical belts (40°N–40°S) have been studied using Microwave Limb Sounder data for the period 1992–1999. Wavelet analysis has been performed to study inter-annual variations in amplitude and phases of the QBO. Latitude-height cross-sections of the amplitudes of temperature and ozone QBO exhibit a double-peak structure near the equator. Phase structure reveals that the temperature QBO descended faster than the ozone QBO. Cross-wavelet analysis shows an anti-phase relation between the amplitudes of the temperature and ozone QBO in the upper stratospheric region, whereas in-phase relation exists in the middle stratospheric region.

Precise dating of East-Asian-Monsoon D/O events during 95–56 ka BP: Based on stalagmite data from Shanbao Cave at Shennongjia, China

Based on 23 U/Th analyses and 532 oxygen isotopic data, an averaged 80-a stalagmite oxygen isotopic composition series was established through 95 to 56 thousand years before present (ka BP) from two speleothems in Shanbao Cave, Shennongjia, central China. Shanbao Cave record (referred to as SB record) replicates well with Hulu Cave record, extending the characteristics of millennial oscillations in East-Asian-Summer-Monsoon (EASM) to the past 95 ka. The trend of the SB record generally follows mid-July solar insolation at 65°N, suggesting that mid-high northern latitude insolation, in the first order, controls changes of EASM intensity. Millennial oscillations of EASM recorded in the stalagmites are well related to the Greenland interstadials referred to as Dansgaard/Oeschger (D/O) events from 1 to 22, indicating that rapid ocean-atmosphere reorganization in North Atlantic has a remote effect in EASM. The well-dated D/O events by stalagmites probably provide an absolute calibration for chronologies of Greenland ice cores. The timings of D/O events in the SB record are different variously from those in Greenland ice cores. For D/O 19 and 20, the age offsets between the stalagmites’ and the Greenland ice cores’ record are significant, larger than the uncertainties of uranium-series dating. The two events in the SB record are younger than those in North GRIP time scale by 1–2 ka, and older than the counterparts in GISP2 by approximately 3–4 ka. A comparison between the SB and Brazil stalagmite record shows an anti-phase relation in millennial-scale monsoon precipitation between the two localities. This supports a mode for the coupled ocean-atmosphere “See-saw”.

Identifying patterns in squash contests using dynamical analysis and human perception.

This report examines the space-time patterns of squash players as they move around the squash court in the context of a dynamical system. The phase relations that describe the squash dyad (i.e., where one player is in relation to the other player) demonstrated a strong tendency towards an anti-phase (180°) relation, as expected. When the data from a number of squash rallies (N = 47) were combined a second stable phase relation of 135° emerged, thus indicating the existence of a previously undetected lead-lag phase relation within the squash dyad. The lead phase relation belonged to the server of the rally in each instance. Further inspections of individual squash rallies demonstrated other properties consistent with a dynamical system description, namely the existence of phase fluctuations (i.e., increased variability in the phase relations), phase transitions (i.e., a switch between stable phase relations), and phase slippages as a result of a missing, or extra, phase cycle for one of the two players. Together, these results indicate that the space-time interactions of squash players might usefully be described in the context of dynamical principles of self-organizing (complex) systems. These findings furthermore suggest that the dynamical properties of the squash dyad may contain important information for identifying the squash patterns that we think we see using visual inspection. To examine this supposition we used the point-light method to represent the movements of the two squash players within a rally as contrasted against a distracter set of varying complexities. Interestingly, humans retained the ability to identify the squash dyad beyond chance even when the distracter set contained squash-like properties. Whether a dynamical analysis of these data is likewise discriminatory in its ability to detect squash behaviours from squash-like behaviours remains to be determined in future research.

Aerosol influence domain of Beijing and peripheral city agglomeration and its climatic effect

The aerosol distribution in Beijing and peripheral cities agglomeration (BPCA) and its regional climatic effect are investigated on the basis of the statistical analyses of satellite Total Ozone Mapping Spectrometer (TOMS) retrieval aerosol optical depth (AOD) and the meteorological data of sunshine duration, fog days, and low cloud cover, observed at Beijing and its peripheral meteorological stations. The analysis on multi-samples variational correction of the satellite remote sensing Moderate Resolution Imaging Spectroradiometer (MODIS) AOD under the clear sky and stable weather condition in conjunction with surface observations reveal that there was a “triangle-like” distribution pattern of the high values of aerosols in the southern “valley” of the “U-shape” megarelief of Beijing and its peripheral areas. The distribution pattern suggests that the large-scale transfer and diffusion of city agglomeration pollutants might form a relatively persistent characteristic spatial distribution of city agglomeration pollutants much larger than city-scale. Under the background of the particular megarelief effect of Beijing and peripheral areas, the high value area of TOMS AOD, as well as regional correlation distribution between clear sky sunshine duration and TOMS AOD are also similar to the composite image of MODIS AOD variational fields, that is to say, the effect of atmospheric aerosols was very distinctive in Beijing and peripheral areas. The high value area of the negative correlation between clear sky sunshine duration and TOMS AOD approximately accorded with the significant negative value area of the sunshine duration deviations of the 1980s to the 1990s, and the daily variations of the AOD also showed an anti-phase relation with those of clear sky sunshine duration. The above high correlation area of the urban aerosol impact of Beijing-Tianjin region leant towards south peripheral area, with its “center of gravity” in the south of Beijing-Tianjin agglomeration, and the main body of the high correlation area prolongating southwards, forming an aerosol influence domain of “eccentric ellipse” shape, that is to say, there was an aerosol influence domain of some “radius” in Beijing City and its peripheral areas, within and outside which sunshine duration, low cloud cover, and fog days showed a remarkable difference in interannual variation trend. At the downstream of the city agglomeration there was a significant interdecadal increment area of fog or low cloud cover, which might be associated with the local climatic feature of the regional flow convergent field in the diffusion process of city agglomeration pollutants in the aerosol influence domain, and such a local dynamical convergence feature might lead to the regional exacerbation of aerosol impact downstream of the city agglomeration. The research result reveals that the significant area of interdecadal change rate of low cloud cover within the aerosol influence domain is correlated with the regional strengthening effect of aerosol impact of the local wind structure in the “downstream plume area” of the city.