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1.
During the developing phase of central Pacific El Nio(CPEN), more frequent TC genesis over the northwest quadrant of the western North Pacific(WNP) is attributed to the horizontal shift of environmental vorticity field.Such a northwestward shift resembles the La Nia composite, even though factors that cause the shift differ(in the La Nia case the relative humidity effect is crucial). Greater reduction of TC frequency over WNP happened during the decaying phase of eastern Pacific El Nio(EPEN) than CPEN, due to the difference of the anomalous Philippine Sea anticyclone strength. The TC genesis exhibits an upward(downward) trend over the northern(southern) part of the WNP,which is linked to SST and associated circulation changes through local and remote effects.  相似文献   

2.
El Ni?o–Southern Oscillation(ENSO) events significantly affect the year-by-year variations of the East Asian winter monsoon(EAWM). However, the effect of La Ni?a events on the EAWM is not a mirror image of that of El Ni?o events. Although the EAWM becomes generally weaker during El Ni?o events and stronger during La Ni?a winters, the enhanced precipitation over the southeastern China and warmer surface air temperature along the East Asian coastline during El Ni?o years are more significant. These asymmetric effects are caused by the asymmetric longitudinal positions of the western North Pacific(WNP) anticyclone during El Ni?o events and the WNP cyclone during La Ni?a events; specifically, the center of the WNP cyclone during La Ni?a events is westward-shifted relative to its El Ni?o counterpart. This central-position shift results from the longitudinal shift of remote El Ni?o and La Ni?a anomalous heating, and asymmetry in the amplitude of local sea surface temperature anomalies over the WNP.However, such asymmetric effects of ENSO on the EAWM are barely reproduced by the atmospheric models of Phase 5 of the Coupled Model Intercomparison Project(CMIP5), although the spatial patterns of anomalous circulations are reasonably reproduced. The major limitation of the CMIP5 models is an overestimation of the anomalous WNP anticyclone/cyclone, which leads to stronger EAWM rainfall responses. The overestimated latent heat flux anomalies near the South China Sea and the northern WNP might be a key factor behind the overestimated anomalous circulations.  相似文献   

3.
The relationship between summer rainfall anomalies in northeast China and two types of El Ni?o events is investigated by using observation data and an AGCM. It is shown that, for different types of El Ni?o events, there is different rainfall anomaly pattern in the following summer. In the following year of a typical El Ni?o event, there are remarkable positive rainfall anomalies in the central-western region of northeast China, whereas the pattern of more rainfall in the south end and less rainfall in the north end of northeast China easily appears in an El Ni?o Modoki event. The reason for the distinct differences is that, associated with the different sea surface temperature anomalies (SSTA) along the equatorial Pacific, the large-scale circulation anomalies along east coast of East Asia shift northward in the following summer of El Ni?o Modoki events. Influenced by the anomalous anticyclone in Philippine Sea, southwesterly anomalies over eastern China strengthens summer monsoon and bring more water vapor to Northeast China. Meanwhile, convergence and updraft is strengthened by the anomalous cyclone right in Northeast China in typical El Ni?o events. These moisture and atmospheric circulation conditions are favorable for enhanced precipitation. However, because of the northward shift, the anomalous anticyclone which is in Philippine Sea in typical El Ni?o cases shifts to the south of Japan in Modoki years, and the anomalous cyclone which is in the Northeast China in typical El Ni?o cases shifts to the north of Northeast China, leading to the “dipole pattern” of rainfall anomalies. According to the results of numerical experiments, we further conform that the tropical SSTA in different types of El Ni?o event can give rise to observed rainfall anomaly patterns in Northeast China.  相似文献   

4.
The western North Pacific anomalous anticyclone(WNPAC) is an important atmospheric circulation system that conveys El Ni?o impact on East Asian climate. In this review paper, various theories on the formation and maintenance of the WNPAC, including warm pool atmosphere–ocean interaction, Indian Ocean capacitor, a combination mode that emphasizes nonlinear interaction between ENSO and annual cycle, moist enthalpy advection/Rossby wave modulation, and central Pacific SST forcing, are discussed. It is concluded that local atmosphere–ocean interaction and moist enthalpy advection/Rossby wave modulation mechanisms are essential for the initial development and maintenance of the WNPAC during El Ni?o mature winter and subsequent spring. The Indian Ocean capacitor mechanism does not contribute to the earlier development but helps maintain the WNPAC in El Ni?o decaying summer.The cold SST anomaly in the western North Pacific, although damped in the summer, also plays a role. An interbasin atmosphere–ocean interaction across the Indo-Pacific warm pool emerges as a new mechanism in summer. In addition, the central Pacific cold SST anomaly may induce the WNPAC during rapid El Ni?o decaying/La Ni?a developing or La Ni?a persisting summer. The near-annual periods predicted by the combination mode theory are hardly detected from observations and thus do not contribute to the formation of the WNPAC. The tropical Atlantic may have a capacitor effect similar to the tropical Indian Ocean.  相似文献   

5.
Based on observational and reanalysis data,the relationships between the eastern Pacific(EP)and central Pacific(CP)types of El Ni?o?Southern Oscillation(ENSO)during the developing summer and the South Asian summer monsoon(SASM)are examined.The roles of these two types of ENSO on the SASM experienced notable multidecadal modulation in the late 1970s.While the inverse relationship between the EP type of ENSO and the SASM has weakened dramatically,the CP type of ENSO plays a far more prominent role in producing anomalous Indian monsoon rainfall after the late 1970s.The drought-producing El Ni?o warming of both the EP and CP types can excite anomalous rising motion of the Walker circulation concentrated in the equatorial central Pacific around 160°W to the date line.Accordingly,compensatory subsidence anomalies are evident from the Maritime Continent to the Indian subcontinent,leading to suppressed convection and decreased precipitation over these regions.Moreover,anomalously less moisture flux into South Asia associated with developing EP El Ni?o and significant northwesterly anomalies dominating over southern India accompanied by developing CP El Ni?o,may also have been responsible for the Indian monsoon droughts during the pre-1979 and post-1979 sub-periods,respectively.El Ni?o events with the same“flavor”may not necessarily produce consistent Indian monsoon rainfall anomalies,while similar Indian monsoon droughts may be induced by different types of El Ni?o,implying high sensitivity of monsoonal precipitation to the detailed configuration of ENSO forcing imposed on the tropical Pacific.  相似文献   

6.
The anomalous behavior of the western Pacific subtropical high(WPSH) in El Nio developing summer is studied based on the composite results of eight major El Nio events during 1979–2013. It is shown that the WPSH tends to retreat eastwards with weak intensity during the developing summer. The anomaly exhibits an intraseasonal variation with a weaker anomaly in June and July and a stronger anomaly in August, indicating that different underlying physical mechanisms may be responsible for the anomalous WPSH during early and late summer periods. In June and July, owing to the cold advection anomaly characterized as a weak northerly anomaly from high latitudes, geopotential height in East Asia is reduced and the WPSH tends to retreat eastwards slightly. By contrast, enhanced convection over the warm pool in August makes the atmosphere more sensitive to El Nio forcing. Consequently, a cyclonic anomaly in the western Pacific is induced, which is consistent with the seasonal march of atmospheric circulation from July to August. Accordingly, geopotential height in the western Pacific is reduced significantly, and the WPSH tends to retreat eastwards remarkably in August. Different from the developing summer, geopotential height in the decaying summer over East Asia and the western Pacific tends to enhance and extend northwards from June to August consistently, reaching the maximum anomaly in August. Therefore, the seasonal march plays an important role in the WPSH anomaly for both the developing and decaying summer.  相似文献   

7.
Bin WANG  Juan LI  Qiong HE 《大气科学进展》2017,34(10):1235-1248
Severe flooding occurred in southern and northern China during the summer of 2016 when the 2015 super El Nio decayed to a normal condition. However, the mean precipitation during summer(June–July-August) 2016 does not show significant anomalies, suggesting that — over East Asia(EA) — seasonal mean anomalies have limited value in representing hydrological hazards. Scrutinizing season-evolving precipitation anomalies associated with 16 El Nio episodes during 1957–2016 reveals that, over EA, the spatiotemporal patterns among the four categories of El Nio events are quite variable, due to a large range of variability in the intensity and evolution of El Nio events and remarkable subseasonal migration of the rainfall anomalies. The only robust seasonal signal is the dry anomalies over central North China during the El Nio developing summer. Distinguishing strong and weak El Nio impacts is important. Only strong El Nio events can persistently enhance EA subtropical frontal precipitation from the peak season of El Nio to the ensuing summer, by stimulating intense interaction between the anomalous western Pacific anticyclone(WPAC) and underlying dipolar sea surface temperature anomalies in the Indo-Pacific warm pool, thereby maintaining the WPAC and leading to a prolonged El Nio impact on EA. A weak El Nio may also enhance the post-El Nio summer rainfall over EA, but through a different physical process: the WPAC re-emerges as a forced response to the rapid cooling in the eastern Pacific. The results suggest that the skillful prediction of rainfall over continental EA requires the accurate prediction of not only the strength and evolution of El Nio, but also the subseasonal migration of EA rainfall anomalies.  相似文献   

8.
The relationships between ENSO and the East Asian-western North Pacific monsoon simulated by the Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 (FGOALS-s2), a state-of-the-art coupled general circulation model (CGCM), are evaluated. For El Nio developing summers, FGOALS-s2 reproduces the anomalous cyclone over the western North Pacific (WNP) and associated negative precipitation anomalies in situ. In the observation, the anomalous cyclone is transformed to an anomalous anticyclone over the WNP (WNPAC) during El Nio mature winters. The model reproduces the WNPAC and associated positive precipitation anomalies over southeastern China during winter. However, the model fails to simulate the asymmetry of the wintertime circulation anomalies over the WNP between El Nio and La Nia. The simulated anomalous cyclone over the WNP (WNPC) associated with La Nia is generally symmetric about the WNPAC associated with El Nio, rather than shifted westward as that in the observation. The discrepancy can partially explain why simulated La Nin a events decay much faster than observed. In the observation, the WNPAC maintains throughout the El Nio decaying summer under the combined effects of local forcing of the WNP cold sea surface temperature anomaly (SSTA) and remote forcing from basinwide warming in the tropical Indian Ocean. FGOALS-s2 captures the two mechanisms and reproduces the WNPAC throughout the summer. However, owing to biases in the mean state, the precipitation anomalies over East Asia, especially those of the Meiyu rain belt, are much weaker than that in the observation.  相似文献   

9.
The NCEP–NCAR reanalysis dataset and the Had ISST dataset(1959–2014) are used to analyze the impact of two types of El Nio events, i.e., eastern Pacific El Nio(EP-El Nio) and central Pacific El Nio(CP-El Nio) events, on the duration of major and minor sudden stratospheric warmings(SSWs) in Northern Hemisphere winter(November to February). Although the frequency of major and minor SSWs during different types of El Nio shows no distinct differences, the duration of both major and minor SSWs during CP-El Nio is shorter than that during EP-El Nio. The spatial distribution of geopotential height anomalies preceding major SSWs resembles the western Pacific(WP) teleconnection pattern, while the spatial distribution of geopotential height anomalies preceding minor SSWs bears similarity to the Pacific–North America(PNA)teleconnection pattern. An enhancement of the strength of both wavenumber 1 and wavenumber 2 is found before major SSWs. Before minor SSWs, wavenumber 1 is also strengthened, but wavenumber 2 is weakened. The analysis also reveals that EP-El Nio tends to induce positive phases of PNA and WP teleconnections, while CP-El Nio induces negative-phase WP teleconnection. As the positive phases of the PNA and WP teleconnections are related to the strengthening of wavenumber 1, EP-El Nio causes an enhancement of wavenumber 1 in the high-latitude upper troposphere and an enhancement of the upward wave flux in the high-latitude stratosphere, accompanied by a negative anomaly in Eliassen–Palm flux divergence in the subpolar stratosphere, which accounts for the longer SSW duration during EP-El Nio than during CP-El Nio.  相似文献   

10.
A set of numerical experiments designed to analyze the oceanic forcing in spring show that the combined forcing of cold (warm) El Ni(n)o (La Ni(n)a) phases in the Ni(n)o4 region and sea surface temperature anomalies (SSTA) in the westerly drifts region would result in abnormally enhanced NorthEast Cold Vortex (NECV) activities in early summer.In spring,the central equatorial Pacific El Ni(n)o phase and westerly drift SSTA forcing would lead to the retreat of non-adiabatic waves,inducing elliptic low-frequency anomalies of tropical air flows.This would enhance the anomalous cyclone-anticyclonecyclone-anticyclone low-frequency wave train that propagates from the tropics to the extratropics and further to the mid-high latitudes,constituting a major physical mechanism that contributes to the early summer circulation anomalies in the subtropics and in the North Pacific mid-high latitudes.The central equatorial Pacific La Ni(n)a forcing in the spring would,on the one hand,induce teleconnection anomalies of high pressure from the Sea of Okhotsk to the Sea of Japan in early summer,and on the other hand indirectly trigger a positive low-frequency East Asia-Pacific teleconnection (EAP) wave train in the lower troposphere.  相似文献   

11.
In recent decades, the typical El Nio events with the warmest SSTs in the tropical eastern Pacific have become less common, and a different of El Nio with the warmest SSTs in the central Pacific, which is flanked on the east and west by cooler SSTs, has become more fre-quent. The more recent type of El Nio was referred to as central Pacific El Nio, warm pool El Nio, or dateline El Nio, or the El Nio Modoki. Central Pacific El Nio links to a different tropical-to-extratropical teleconnection and exerts different impacts on climate, and several classification approaches have been proposed. In this study, a new classification approach is proposed, which is based on the linear combination (sum or difference) of the two leading Empirical Orthogonal Functions (EOFs) of tropical Pacific Ocean sea surface temperature anomaly (SSTA), and the typical El Ni o index (TENI) and the central El Nio index (CENI) are able to be derived by projecting the observed SSTA onto these combinations. This classification not only reflects the characteristics of non-orthogonality between the two types of events but also yields one period peaking at approximate two to seven years. In particular, this classification can distin-guish the different impacts of the two types of events on rainfall in the following summer in East China. The typical El Nio events tend to induce intensified rainfall in the Yangtze River valley, whereas the central Pacific El Nio tends to induce intensified rainfall in the Huaihe River valley. Thus, the present approach may be appropriate for studying the impact of different types of El Nio on the East Asian climate.  相似文献   

12.
正In recent decades, the typical El Nio events with the warmest SSTs in the tropical eastern Pacific have become less common, and a different of El Nio with the warmest SSTs in the central Pacific, which is flanked on the east and west by cooler SSTs, has become more fre-quent. The more recent type of El Nio was referred to as central Pacific El Nio, warm pool El Nio, or dateline El Nio, or the El Nio Modoki. Central Pacific El Nio links to a different tropical-to-extratropical teleconnection and exerts different impacts on climate, and several classification approaches have been proposed. In this study, a new classification approach is proposed, which is based on the linear combination (sum or difference) of the two leading Empirical Orthogonal Functions (EOFs) of tropical Pacific Ocean sea surface temperature anomaly (SSTA), and the typical El Ni o index (TENI) and the central El Nio index (CENI) are able to be derived by projecting the observed SSTA onto these combinations. This classification not only reflects the characteristics of non-orthogonality between the two types of events but also yields one period peaking at approximate two to seven years. In particular, this classification can distin-guish the different impacts of the two types of events on rainfall in the following summer in East China. The typical El Nio events tend to induce intensified rainfall in the Yangtze River valley, whereas the central Pacific El Nio tends to induce intensified rainfall in the Huaihe River valley. Thus, the present approach may be appropriate for studying the impact of different types of El Nio on the East Asian climate.  相似文献   

13.
The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o.  相似文献   

14.
Interannual variability of landfalling tropical cyclones(TCs) in China during 1960-2010 is investigated.By using the method of partial least squares regression(PLS-regression),canonical ENSO and ENSO Modoki are identified to be the factors that contribute to the interannual variability of landfalling TCs.El Ni o Modoki years are associated with a greater-than-average frequency of landfalling TCs in China,but reversed in canonical El Ni o years.Significant difference in genesis locations of landfalling TCs in China for the two kinds of El Ni o phases occurs dominantly in the northern tropical western North Pacific(WNP).The patterns of low-level circulation anomalies and outgoing longwave radiation(OLR) anomalies associated with landfalling TC genesis with different types of El Ni o phases are examined.During canonical El Ni o years,a broad zonal band of positive OLR anomalies dominates the tropical WNP,while the circulation anomalies exhibit a meridionally symmetrical dipole pattern with an anticyclonic anomaly in the subtropics and a cyclonic anomaly near the tropics.In El Ni o Modoki years,a vast region of negative OLR anomalies,roughly to the south of 25°N with a strong large-scale cyclonic anomaly over the tropical WNP,provides a more favorable condition for landfalling TC genesis compared to its counterpart during canonical El Ni o years.For more landfalling TCs formed in the northern tropical WNP in El Ni o Modoki years,there are more TCs making landfall on the northern coast of China in El Ni o Modoki years than in canonical El Ni o years.The number of landfalling TCs is slightly above normal in canonical La Ni a years.Enhanced convection is found in the South China Sea(SCS) and the west of the tropical WNP,which results in landfalling TCs forming more westward in canonical La Ni a years.During La Ni a Modoki years,the landfalling TC frequency are below normal,owing to an unfavorable condition for TC genesis persisting in a broad zonal band from 5°N to 25°N.Since the western North Pacific subtropical high(WNPSH) in La Ni a Modoki years is located in the westernmost region,TCs mainly make landfall on the south coast of China.  相似文献   

15.
The characteristics of sea surface temperature anomalies(SSTAs)in the tropical oceans and their influences on the onset of South China Sea summer monsoon(SCSSM)have been studied.The anomaly of SST in tropical Pacific Ocean exerts persistence impact for one to three months on atmospheric circulations.If the warm pool becomes anomalously warmer during an earlier period from February to April,the SCSSM breaks out earlier,and vice versa.Singular value decomposition(SVD)and composite analysis have shown that,in La Ni a pattern,the convection over Western Pacific will occur earlier and be stronger than normal,which favors the convergence at a lower layer over Western Pacific,as well as the strengthening of upwelling branch of Walker circulation,leading to an earlier burst of westerly in the southern South China Sea.Moreover,the convection in Sumatra appears earlier than normal and favors the westerly evolution in eastern Indian Ocean,resulting in the splitting of the subtropical high belt and an early onset of SCSSM.However,the atmospheric circulation anomaly is reversed in El Nio pattern.  相似文献   

16.
El Nio Modoki,similar to but different from canonical El Nio,has been observed since the late1970s.In this paper,using HadISST and NCEP/NCAR wind data,we analyze the relationship between El Nio Modoki and Sea Surface Temperature(SST)in the offshore area of China and its adjacent waters for different seasons.Our results show a significant negative correlation between El Nio Modoki in summer and SST in autumn in the offshore area of China and its adjacent waters,particularly for regions located in the east of the Kuroshio.It is also found that during El Nio Modoki period,anomalous northerlies prevail over the regions from the northern part of the Philippines to the offshore area of China,indicating that the northerlies are unfavorable for the transport of warm water from the western tropical Pacific to the mid-latitude area.Consequently,El Nio Modoki in summer may play a substantial role in cold SST anomalies in the offshore area of China and its adjacent waters in autumn through the influence of the Kuroshio,with a lagged response of the ocean to the atmospheric wind field.  相似文献   

17.
A central Pacific(CP) El Ni?o event occurred in 2018/19. Previous studies have shown that different mechanisms are responsible for different subtypes of CP El Ni?o events(CP-I El Ni?o and CP-II El Ni?o). By comparing the evolutions of surface winds, ocean temperatures, and heat budgets of the CP-I El Ni?o, CP-II El Ni?o, and 2018/19 El Ni?o, it is illustrated that the subtropical westerly anomalies in the North Pacific, which led to anomalous convergence of Ekman flow and surface warming in the ...  相似文献   

18.
This study reveals that the interannual variability of the western edge of the western North Pacific (WNP) subtropical high (WNPSH) in early summer experienced an interdecadal decrease around 1990. Correspondingly, the zonal movement of the WNPSH and the zonal extension of the high-pressure anomaly over the WNP (WNPHA) in abnormal years possess smaller ranges after 1990. The different influences of the tropical SSTAs are important for this interdecadal change, which exhibit slow El Ni?o decaying pattern before 1990 while rapid transformation from El Ni?o to La Ni?a after 1990. The early summer tropical SSTAs and the relevant atmospheric circulation anomalies present obvious interdecadal differences. Before 1990, the warm SSTAs over the northern Indian Ocean and southern South China Sea favor the WNPHA through eastward-propagating Kelvin wave and meridional-vertical circulation, respectively. Meanwhile, the warm SSTA over the tropical central Pacific induces anomalous ascent to its northwest through the Gill response, which could strengthen the anomalous descent over the WNP through meridional-vertical circulation and further favor the eastward extension of the WNPHA to central Pacific. After 1990, the warm SSTAs over the Maritime Continent and northern Indian Ocean cause the WNPHA through meridional-vertical and zonal-vertical circulation, respectively. Overall, the anomalous warm SSTs and ascent and the resultant anomalous descent over the WNP are located more westward and southward after 1990 than before 1990. Consequently, the WNPHA features narrower zonal range and less eastward extension after 1990, corresponding to the interdecadal decease in the interannual variability of the western edge of the WNPSH. On the other hand, the dominant oscillation period of ENSO experienced an interdecadal reduction around 1990, contributing to the change of the El Ni?o SSTA associated with the anomalous WNPSH from slow decaying type to rapid transformation type.  相似文献   

19.
The zonal and meridional circulations and their variability arc examined on the basis of the surface wind data for 1950-1979. The climatological mean zonal wind and its divergence arc examined in reference to the Walker Circulation. The role played by the meridional circulation in contributing to convergence of the surface wind field within the equatorial zone is emphasized. Regression coefficients are used to infer seasonal mean anomalies of divergence of the surface wind in years when the sea level pressure is 1 hPa above normal at Darwin, a condition representative of El Nino events. It is shown that anomalies in the divergence associated with the meridional wind component are primarily responsible for the heavy precipitation in the Central Pacific, while the anomalous divergence associated with the zonal wind component may cause the drought in the Western Pacific near Indonesia. A similar pattern of divergence anomalies is evident during three consecutive seasons beginning in northern summer and end  相似文献   

20.
The impact of sea surface temperature (SST) on winter haze in Guangdong province (WHDGD) was analyzed on the interannual scale. It was pointed out that the northern Indian Ocean and the northwest Pacific SST play a leading role in the variation of WHDGD. Cold (warm) SST anomalies over the northern Indian Ocean and the Northwest Pacific stimulate the eastward propagation of cold (warm) Kelvin waves through the Gill forced response, causing Ekman convergence (divergence) in the western Pacific, inducing abnormal cyclonic (anticyclonic) circulation. It excites the positive (negative) Western Pacific teleconnection pattern (WP), which results in the temperature and the precipitation decrease (increase) in Guangdong and forms the meteorological variables conditions that are conducive (not conducive) to the formation of haze. ENSO has an asymmetric influence on WHDGD. In El Ni?o (La Ni?a) winters, there are strong (weak) coordinated variations between the northern Indian Ocean, the northwest Pacific, and the eastern Pacific, which stimulate the negative (positive) phase of WP teleconnection. In El Ni?o winters, the enhanced moisture is attributed to the joint effects of the horizontal advection from the surrounding ocean, vertical advection from the moisture convergence, and the increased atmospheric apparent moisture sink (Q2) from soil evaporation. The weakening of the atmospheric apparent heat source (Q1) in the upper layer is not conducive to the formation of inversion stratification. In contrast, in La Ni?a winters, the reduced moisture is attributed to the reduced upward water vapor transport and Q2 loss. Due to the Q1 increase in the upper layer, the temperature inversion forms and suppresses the diffusion of haze.  相似文献   

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