Background Sand and dust storm, as one of the main disastrous weathers that affect northern China, not only affect the people health and normal life, but cause the short-term climatic changes due to the direct and ind...Background Sand and dust storm, as one of the main disastrous weathers that affect northern China, not only affect the people health and normal life, but cause the short-term climatic changes due to the direct and indirect radiation of the earth-atmosphere system through the dust floating in the sky. The sand and dust weather and its potential harm on the national economy, ecological environment, social activities and other aspects have aroused worldwide concern.展开更多
In this study, the effect of the tropical North Atlantic (TNA) sea surface temperature (SST) variation in inducing the circulation anomaly in the Indo-East Asian monsoon (IEAM) region is investigated through the obser...In this study, the effect of the tropical North Atlantic (TNA) sea surface temperature (SST) variation in inducing the circulation anomaly in the Indo-East Asian monsoon (IEAM) region is investigated through the observational analysis and numerical model-ing. The observational analysis shows that the TNA summer SST is positively correlated with the preceding winter Ni?o3 SST and is simultaneously correlated with the circulation in the IEAM region. The simultaneous circulation pattern resembles that of the ENSO-decaying summer. The positive correlation between the TNA SST and the Ni?o3 region SST is primarily ascribed to the surface latent heat flux and short wave radiation anomalies induced by the ENSO teleconnection. Coupled general circulation model experiments show that, while including the air-sea coupling in the Atlantic, the model can reproduce the main features of the IEAM circulation, such as an anomalous anticyclone over the western North Pacific (WNP) and southerly anomalies over southeast China. While the climatological Atlantic SST is prescribed, the circulation over the WNP displays a significantly dif-ferent pattern, with an eastward migration of the WNP anticyclone and the associated northerly anomalies over southeast China. It is argued that anticyclonic shear and Ekman divergence associated with the atmospheric Kelvin wave response to the TNA warm SSTA forcing is the primary mechanism for the generation of the anomalous anticyclone in WNP. The results presented in this study provide a teleconnection pattern between TNA and short-term climate variability in IEAM region.展开更多
The E1 Nifio-Southern Oscillation （ENSO） phenomenon in the tropical Pacific has been a focus of ocean and climate studies in the last few decades. Recently, the short-term climate variability in the tropical Indian ...The E1 Nifio-Southern Oscillation （ENSO） phenomenon in the tropical Pacific has been a focus of ocean and climate studies in the last few decades. Recently, the short-term climate variability in the tropical Indian Ocean has attracted increasingly more attention, especially with the proposition of the Indian Ocean Dipole （IOD） mode. However, these phenomena are often stud- ied separately without much consideration of their interaction. Observations reveal a striking out-of-phase relationship between zonal gradients of sea surface height anomaly （SSHA） and sea surface temperature anomaly （SSTA） in the tropical Indian and Pacific Oceans. Since the two oceans share the ascending branch of the Walker cells over the warm pool, the variation within one of them will affect the other. The accompanied zonal surface wind anomalies are always opposite over the two basins, thus producing a tripole structure with opposite zonal gradients of SSHA/SSTA in the two oceans. This mode of variability has been referred to as Indo-Pacific Tripole （IPT）. Based on observational data analyses and a simple ocean-atmosphere coupled model, this study tries to identify the characteristics and physical mechanism of IPT with a particular emphasis on the rela- tionships among ENSO, IOD, and IPT. The model includes the basic oceanic and atmospheric variables and the feedbacks between them, and takes into account the inter-basin connection through an atmospheric bridge, thus providing a valuable framework for further research on the short-term tropical climate variability.展开更多
The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variat...The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.展开更多
文摘Background Sand and dust storm, as one of the main disastrous weathers that affect northern China, not only affect the people health and normal life, but cause the short-term climatic changes due to the direct and indirect radiation of the earth-atmosphere system through the dust floating in the sky. The sand and dust weather and its potential harm on the national economy, ecological environment, social activities and other aspects have aroused worldwide concern.
基金supported by the National Basic Research Program of China (2004CB418302)the National Natural Science Foundation of China (40921003)the International S&T Cooperation Project of the Ministry of Science and Technology of China (2009DFA21430)
文摘In this study, the effect of the tropical North Atlantic (TNA) sea surface temperature (SST) variation in inducing the circulation anomaly in the Indo-East Asian monsoon (IEAM) region is investigated through the observational analysis and numerical model-ing. The observational analysis shows that the TNA summer SST is positively correlated with the preceding winter Ni?o3 SST and is simultaneously correlated with the circulation in the IEAM region. The simultaneous circulation pattern resembles that of the ENSO-decaying summer. The positive correlation between the TNA SST and the Ni?o3 region SST is primarily ascribed to the surface latent heat flux and short wave radiation anomalies induced by the ENSO teleconnection. Coupled general circulation model experiments show that, while including the air-sea coupling in the Atlantic, the model can reproduce the main features of the IEAM circulation, such as an anomalous anticyclone over the western North Pacific (WNP) and southerly anomalies over southeast China. While the climatological Atlantic SST is prescribed, the circulation over the WNP displays a significantly dif-ferent pattern, with an eastward migration of the WNP anticyclone and the associated northerly anomalies over southeast China. It is argued that anticyclonic shear and Ekman divergence associated with the atmospheric Kelvin wave response to the TNA warm SSTA forcing is the primary mechanism for the generation of the anomalous anticyclone in WNP. The results presented in this study provide a teleconnection pattern between TNA and short-term climate variability in IEAM region.
文摘The E1 Nifio-Southern Oscillation （ENSO） phenomenon in the tropical Pacific has been a focus of ocean and climate studies in the last few decades. Recently, the short-term climate variability in the tropical Indian Ocean has attracted increasingly more attention, especially with the proposition of the Indian Ocean Dipole （IOD） mode. However, these phenomena are often stud- ied separately without much consideration of their interaction. Observations reveal a striking out-of-phase relationship between zonal gradients of sea surface height anomaly （SSHA） and sea surface temperature anomaly （SSTA） in the tropical Indian and Pacific Oceans. Since the two oceans share the ascending branch of the Walker cells over the warm pool, the variation within one of them will affect the other. The accompanied zonal surface wind anomalies are always opposite over the two basins, thus producing a tripole structure with opposite zonal gradients of SSHA/SSTA in the two oceans. This mode of variability has been referred to as Indo-Pacific Tripole （IPT）. Based on observational data analyses and a simple ocean-atmosphere coupled model, this study tries to identify the characteristics and physical mechanism of IPT with a particular emphasis on the rela- tionships among ENSO, IOD, and IPT. The model includes the basic oceanic and atmospheric variables and the feedbacks between them, and takes into account the inter-basin connection through an atmospheric bridge, thus providing a valuable framework for further research on the short-term tropical climate variability.
基金supported by National Natural Science Foundation of China (Grant No. 60874111)Qing Lan Project of Jiangsu Province and College Science Foundation of Jiangsu Province (Grant No. 07KJD120128)
文摘The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.
