East Asian summer monsoon precipitation (EASMP) features complicated interdecadal variability with multiple time periods and spatial patterns. Using century-long datasets of HadISST, CRU ...precipitation, and the ECMWF twentieth-century reanalysis (ERA-20C), this study examines the joint influence of three oceanic interdecadal signals i.e., Pacific decadal oscillation (PDO), Atlantic multidecadal oscillation (AMO), and Indian Ocean Basin mode (IOBM) on the EASMP, which, however, is found not to be simply a linear combination of their individual effects. When PDO and AMO are out of phase, the same-sign SST anomalies occur in the North Pacific and North Atlantic, and a zonally orientated teleconnection wave train appears across the Eurasian mid-to-high latitudes, propagating from the North Atlantic to northern East Asia along the Asian westerly jet waveguide. Correspondingly, the interdecadal precipitation anomalies are characterized by a meridional tripole mode over eastern China. When PDO and AMO are in phase, with opposite sign SST anomalies in the North Pacific and North Atlantic, the sandwich pattern of anomalous stationary Rossby wavenumber tends to reduce the effect of the waveguide in the eastern Mediterranean region, and the teleconnection wave train from the North Atlantic travels only to western central Asia along a great circle route, causing Indian summer monsoon precipitation (ISMP) anomalies. The ISMP anomalies, in turn, interact with the teleconnection wave train induced by the PDO and AMO, leading to a meridional dipole mode of interdecadal precipitation anomalies over eastern China. Through the impact on the ISMP, the IOBM exerts significantly linear modulation on the combined impacts of PDO and AMO, especially over northern East Asia.
The structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean–atmosphere system are examined in this study, using the NCEP/NCAR atmospheric reanalysis, HadISST SST ...and Simple Ocean Data Assimilation data for 1960–2010. The midlatitude decadal anomalies associated with the Pacific Decadal Oscillation are identified, being characterized by an equivalent barotropic atmospheric low (high) pressure over a cold (warm) oceanic surface. Such a unique configuration of decadal anomalies can be maintained by an unstable ocean–atmosphere interaction mechanism in the midlatitudes, which is hypothesized as follows. Associated with a warm PDO phase, an initial midlatitude surface westerly anomaly accompanied with intensified Aleutian low tends to force a negative SST anomaly by increasing upward surface heat fluxes and driving southward Ekman current anomaly. The SST cooling tends to increase the meridional SST gradient, thus enhancing the subtropical oceanic front. As an adjustment of the atmospheric boundary layer to the enhanced oceanic front, the low-level atmospheric meridional temperature gradient and thus the low-level atmospheric baroclinicity tend to be strengthened, inducing more active transient eddy activities that increase transient eddy vorticity forcing. The vorticity forcing that dominates the total atmospheric forcing tends to produce an equivalent barotropic atmospheric low pressure north of the initial westerly anomaly, intensifying the initial anomalies of the midlatitude surface westerly and Aleutian low. Therefore, it is suggested that the midlatitude ocean–atmosphere interaction can provide a positive feedback mechanism for the development of initial anomaly, in which the oceanic front and the atmospheric transient eddy are the indispensable ingredients. Such a positive ocean–atmosphere feedback mechanism is fundamentally responsible for the observed decadal anomalies in the midlatitude North Pacific ocean–atmosphere system.
Objective
To evaluate the association between serum copper levels and lung cancer risk.
Methods
We searched the electronic PubMed, WanFang, CNKI, and SinoMed databases to identify studies including ...information on serum copper levels and lung cancer. Standard mean differences and corresponding 95% confidence intervals were calculated using Stata 12.0 software. We performed a meta-analysis on the identified studies overall and according to geographic location. We also evaluated heterogeneity among the studies and the occurrence of publication bias.
Results
Thirty-three articles including 3026 cases and 9439 controls were included in our study. The combined results showed that serum copper levels were higher in patients with lung cancer compared with controls without lung cancer, though the results showed high heterogeneity. In a subgroup analysis according to geographic location, significant associations between copper levels and lung cancer were found for both Asian and European populations. No publication bias was detected in this meta-analysis.
Conclusions
High serum copper levels could increase the risk of lung cancer, suggesting that environmental copper exposure may be a risk factor for the development of lung cancer.
The stochastic sea surface temperature (SST) anomalies are always present because of the internal oceanic variability due to small‐scale SST variability and based on a set of ensemble experiments ...forced by Pacific Decadal Oscillation‐related midlatitude North Pacific SST anomalies with and without oceanic stochastic forcing, their influences on atmospheric variability in coarse‐resolution models are investigated in this study. Comparisons of experiment results show that oceanic stochastic forcing can improve the simulated atmospheric response by generating more organized atmospheric transient eddies through the increases of both thermal activity and atmospheric baroclinicity, similar to the high‐resolution observations and simulations. Dynamic diagnostics further reveal the dominant contributions of corresponding transient eddy vorticity forcing to the significantly enhanced westerly wind with equivalent barotropic structure. It suggests that the oceanic stochastic forcing is important and nonnegligible for the understanding and theory of oceanic feedback to the atmosphere in the midlatitudes.
Plain Language Summary
The atmospheric response to the midlatitude North Pacific sea surface temperature (SST) anomalies are essential albeit weak for understanding the associated air‐sea interaction there, wherein storm track plays an important role. To adequately capture the storm tracks and large‐scale atmospheric structures as well, high‐resolution SST with detailed oceanic fronts and eddies are required in fine‐resolution atmospheric general circulation models. One of the important effects of high‐resolution SST is to enhance the atmospheric transient eddies by introducing more internal oceanic variabilities, which can be obtained by an alternative way in this study, that is, adding extra oceanic stochastic forcing in a coarse‐resolution atmospheric general circulation model. A set of ensemble experiments and dynamic diagnostics illustrate that oceanic stochastic forcing can generate many more atmospheric transient eddies through the increases of thermal activity and atmospheric baroclinicity, and further enhance large‐scale atmospheric response to the midlatitude North Pacific SST anomalies. Without increasing the amount of oceanic fronts and eddies and the capability of resolving the atmospheric transient eddies, this study illustrates that the oceanic stochastic forcing is important and nonnegligible for the understanding and theory of oceanic feedback to the atmosphere in the midlatitudes.
Key Points
Oceanic stochastic forcing can produce organized large‐scale atmospheric structures as well as strengthened atmospheric transient eddies
Storm tracks serve as the bridge between ocean stochastic forcing and the large‐scale atmospheric response
Introducing oceanic stochastic forcing can advance the understanding and theory of oceanic feedback to the atmosphere in the midlatitudes
This study examines the relationship between the zonal oscillation of the western Pacific subtropical high (WPSH) and underneath sea surface temperature (SST) variation on a subseasonal time scale, ...associated with the persistent heavy rainfall (PHR) events over the middle and lower reaches of the Yangtze River valley (MLYRV) in China. A total of 76 PHR events and 45 break events in the summers of 1979–2011 are first identified over the MLYRV and divided into early and late summer groups. During the PHR events over the MLYRV for both groups, the WPSH stretches more westward, accompanied by the positive anomalies of the 500-hPa geopotential height field over East Asia and its coastal region south of 30°N and the subseasonal warmer SSTs beneath the WPSH western edge. The time-lagged composites suggest that the WPSH western edge exhibits westward-then-eastward migration on a subseasonal time scale for the PHR events. The zonal changes of the WPSH and anomalous circulation and SST anomaly (SSTA) signals for break events is almost the mirror image of that for the PHR events for the early summer group. Accompanied by the WPSH westward extension, the increased incident solar radiation and decreased latent heat flux over the coastal region of East Asia contribute to the positive SSTAs beneath the western part of the WPSH. The positive SSTAs construct a convective instability that provides an adverse condition for maintaining the anticyclonic anomalies in the mid–lower levels. The persistent SST warming is also favorable to the transition of low-level circulation from anticyclonic to cyclonic anomalies over the coastal region. As a result, the WPSH withdraws eastward after the peak of the rainfall events over the MLYRV.
Aerosols have significant and complex impacts on regional climate in East Asia. Cloud‐aerosol‐precipitation interactions (CAPI) remain most challenging in climate studies. The quantitative ...understanding of CAPI requires good knowledge of aerosols, ranging from their formation, composition, transport, and their radiative, hygroscopic, and microphysical properties. A comprehensive review is presented here centered on the CAPI based chiefly, but not limited to, publications in the special section named EAST‐AIRcpc concerning (1) observations of aerosol loading and properties, (2) relationships between aerosols and meteorological variables affecting CAPI, (3) mechanisms behind CAPI, and (4) quantification of CAPI and their impact on climate. Heavy aerosol loading in East Asia has significant radiative effects by reducing surface radiation, increasing the air temperature, and lowering the boundary layer height. A key factor is aerosol absorption, which is particularly strong in central China. This absorption can have a wide range of impacts such as creating an imbalance of aerosol radiative forcing at the top and bottom of the atmosphere, leading to inconsistent retrievals of cloud variables from space‐borne and ground‐based instruments. Aerosol radiative forcing can delay or suppress the initiation and development of convective clouds whose microphysics can be further altered by the microphysical effect of aerosols. For the same cloud thickness, the likelihood of precipitation is influenced by aerosols: suppressing light rain and enhancing heavy rain, delaying but intensifying thunderstorms, and reducing the onset of isolated showers in most parts of China. Rainfall has become more inhomogeneous and more extreme in the heavily polluted urban regions.
Key Points
East Asia has suffered heavy aerosol loading of diverse properties
Strong absorbing aerosols lower the boundary layer, suppress convection, and worsens air pollution
The joint effects of aerosol on radiation and clouds alter the development of clouds and precipitation and regional climate
ABSTRACT
In this study, potential impacts of the North Pacific subarctic frontal zone (SAFZ) variation, including its intensity variation and meridional shift, upon the subseasonally varying North ...Pacific storm track are investigated by using the 100‐year reanalysis data sets. Regression analysis indicates that the changes in the SAFZ intensity and meridional position have significant influence on the North Pacific storm track, which intensifies with the strengthening of the SAFZ and moves northwards following the northwards shift of the SAFZ. However, the storm‐track response pattern exhibits distinct differences from one calendar month to another. Specifically, the storm‐track response to the SAFZ intensity variation is strongest in February and March; while its response to the SAFZ meridional shift is most pronounced in November and December. However, the storm‐track response is relatively weak in January. Further analysis shows that the intensified (or northwards shifted) SAFZ would result in changes in the near‐surface baroclinicity and hence affects the storm track, while the weak storm‐track response in January is not the result of the anomalous near‐surface baroclinicity. The investigation of the local energetics reveals that changes in the baroclinic energy conversion (BCEC) associated with the SAFZ variation are consistent with the storm‐track anomalies, indicating that the BCEC plays a crucial role in modulating the subseasonal changes in the storm‐track response. In January, the weakened BCEC contributes to the reduced storm‐track response to the SAFZ variation.
This study revealed that the storm track intensifies with the strengthening of the subarctic frontal zone (SAFZ) and moves northwards following the northwards shift of the SAFZ as shown in the figure. The storm‐track response to the SAFZ intensity variation is strongest in February and March, while its response to the SAFZ meridional shift is most pronounced in November and December. The storm‐track response is relatively weak in January.
North Atlantic Oscillation (NAO) has a significant impact on surrounding winter weather and climate. However, the causes of its occasional reversal between early and late winter remain unclear. This ...study proposes a mechanism for the mid‐winter reversal of NAO from the perspective of local midlatitude air‐sea interaction. Strong sea surface temperature (SST) tripole events, which are defined by empirical orthogonal function of winter‐mean interannual North Atlantic SST anomalies, are primarily induced by NAO in early winter and peak in January. In late winter, the persistent SST tripole exerts active feedback on atmosphere through diabatic heat and transient eddy forcing. The resulting atmospheric circulation anomalies exhibit an almost reversed NAO pattern in February, which forms a wavetrain originating above the Gulf Stream and propagating to the Middle East and weakens the former SST tripole. Consequently, significant reversals of air temperature anomalies occur in Europe and the Caspian Sea area between February and December.
Plain Language Summary
The North Atlantic Oscillation (NAO) is a crucial atmospheric system that significantly impacts the weather and climate of the surrounding regions during winter. However, it often reverses between early and late winter, and the reasons for its mid‐winter reversal remain unclear. The NAO behavior can be influenced by multiple factors, such as atmospheric internal processes, underlying surface, and remote climate system, which makes the issue more complex. This study highlights the role of underlying sea surface temperature anomalies (SSTAs) in the mid‐winter reversal of NAO. The North Atlantic SSTAs are closely associated with the NAO and exhibit a tripole pattern. For strong sea surface temperature (SST) tripole events, the NAO primarily induces the early winter North Atlantic SST tripole. The SSTAs develop in early winter, peak in January, and feedback on the atmospheric circulation in late winter. The atmospheric circulation anomalies exhibit an almost reversed NAO pattern in February, forming a wavetrain that propagates above the Gulf Stream to the Middle East. As a result, during the warm phase of the SST tripole, Europe experiences colder temperatures, and the Caspian Sea experiences warmer temperatures in February than usual, as opposed to the positive NAO’s control over warm Europe and cold Caspian Sea in December.
Key Points
In early winter, North Atlantic Oscillation (NAO) forces a North Atlantic sea surface temperature (SST) tripole, which persists and tends to induce a nearly reversed NAO pattern in February
SST tripole induces a wavetrain over the Gulf Stream to the Middle East via diabatic heating and transient eddy forcing in February
As a result, there are remarkable reversals of air temperature anomalies in Europe and Caspian Sea area between February and December
Combining several reanalysis and in situ data sets, the low potential vorticity (PV) water masses are Lagrangian tracked in the subsurface ocean southwestwardly from the midlatitude Pacific in ...winter, which have significant interannual variations. The subsurface low PV water transport is proved to be closely related to the interannual variation of atmospheric North Pacific westerly jet by changing the subtropical countercurrent (STCC) and the sea surface temperature gradient adjacent. Specifically, the enhanced subsurface low PV water mass transported to the west of STCC causes strengthened northeastward warm water transport of STCC branching, and the weakened eastward branching. Therefore, significant negative temperature gradient anomalies of sea surface and lower atmosphere generate in the midlatitude to the east of 170°E. The corresponding local weakened lower atmospheric baroclinity and wave activities then lead to the convergence of anomalous downward atmospheric baroclinic Rossby waves and eventually the upper westerly jet deceleration.
Plain Language Summary
Researches on mode water usually focused on the water mass analysis and the surface forcing during its subduction process. However, less attention was paid to the forcing of mode water on climate, especially on upper and middle atmospheric circulation. Using observations and reanalysis datasets, this research figures out that the interannual variations of the subsurface subtropical countercurrent (STCC) are forced by the southwestward transport of subducted low potential vorticity water masses in the North Pacific in winter. Due to the northeastward tilt of the climatological STCC, the change of the accompanying subsurface temperature gradient shows reverse phases in the east–west direction. In the stronger STCC years, the significant weakening of the sea surface temperature gradient is revealed to the east of 170°E, which may be attributed to the local air‐sea coupling. Then obvious atmospheric upper westerly jet deceleration ensues, accompanied with the weakened atmospheric baroclinity and divergent downward baroclinic Rossby wave, which is important for the winter weather and climate of downstream regions.
Key Points
The interannual variation of subtropical countercurrent (STCC) velocity is closely related to the volume of low potential vorticity (PV) water in the western subsurface ocean in winter
With more subsurface low PV water masses Lagrangian tracked southwestwardly, an enhanced baroclinic current exists to the west of STCC
Accompanied by the sea surface temperature gradient anomalies near STCC, a corresponding interannual variation of atmospheric winter westerly jet was revealed
Using observational analysis and numerical experiments, we identify that the dipole mode of spring surface wind speed (SWS) over the Tibetan Plateau (TP) could act as a trigger for subsequent winter ...El Niño–Southern Oscillation events. During the positive phase of spring SWS dipole mode (south‐positive and north‐negative), a self‐sustaining “negative sensible heating–baroclinic structure” prevails over the western TP, which is characterized by negative surface sensible heating anomalies, anomalous low‐level anticyclones, and mid–high‐level cyclones. The “negative sensible heating–baroclinic structure” stimulates the surface westerly wind anomalies over the tropical western Pacific in May through two pathways, favoring the occurrence of subsequent El Niño events. One is through weakening the zonal monsoon circulation over the tropical Indian Ocean and the Walker circulation over the tropical western Pacific. The other is modulating the air–sea interaction over the North Pacific through triggering Rossby waves. The negative SWS dipole mode tends to induce La Niña events.
Plain Language Summary
El Niño–Southern Oscillation (ENSO) can exert pronounced climate impacts over the tropical Pacific and other remote regions. Meanwhile, the occurrence of ENSO events is also affected by local tropical Pacific and non‐local factors. As an elevated, huge, and intense heat source over the subtropics, Tibetan Plateau (TP) thermal forcing exerts significant influences on atmospheric circulations and oceans across the whole globe. This study explores the impact of spring TP thermal forcing on the formation of ENSO in following winter. In the observations, the south–north dipole modes of spring surface sensible heating and surface wind speed over the TP can stimulate the surface zonal wind anomalies over the tropical western Pacific in May through two pathways, favoring the occurrence of subsequent ENSO events. One is through influencing the zonal monsoon circulation over the tropical Indian Ocean and the Walker circulation over the tropical western Pacific. The other is modulating the air–sea interaction over the North Pacific through triggering Rossby waves. These two pathways are well reproduced in numerical experiments.
Key Points
Spring positive surface wind speed (SWS) dipole mode over Tibetan Plateau is closely connected with a “negative sensible heating‐baroclinic structure”
Spring positive SWS dipole mode induces winter El Niño by modulating surface westerly wind anomalies over tropical western Pacific in May
Surface westerly wind anomalies over tropical western Pacific in May are induced through gearing between the Indian and Pacific oceans and seasonal footprinting mechanism processes
PDF
