An extreme warming hit Europe in summer of the year 2015. The present paper investigates the relationship between the North Atlantic Oscillation Index (NAO), Southern Oscillation Index (SOI) and El-Nino 3.4 and heat w...An extreme warming hit Europe in summer of the year 2015. The present paper investigates the relationship between the North Atlantic Oscillation Index (NAO), Southern Oscillation Index (SOI) and El-Nino 3.4 and heat waves that persist over the western and central Europe in the summer of 2015. The NCEP/NCAR Reanalysis daily dataset of the mean surface air temperature for the domains of the western and central Europe for summer months (June, July and August) of the year, 2015 has used. In addition, the time cross-section analysis of the daily gridded operational data for the mean surface air temperature over the western and central Europe from 1 June to 31 August 2015 has done. Moreover, daily datasets of the NAO, SOI, and El-Nino 3.4 for that period have used. The time series, time cross section, anomaly and correlation coefficient techniques are used to analyze the data sets. The results revealed that the cases of heat waves that existed over the western and central Europe through the summer season of the year 2015 were controlled distinctly by the negative phase of the NAO and positive phase of ENSO.展开更多
基于贝叶斯模式平均方法(Bayesian Model Averaging),发展了一个NINO3.4指数的多模式客观权重集合预报方法(简称OBJ)。该方法基于训练期内单个模式的预报结果,用线性回归订正单个预报的偏差,依据模式的预报效果估计单个模式的权重。利用...基于贝叶斯模式平均方法(Bayesian Model Averaging),发展了一个NINO3.4指数的多模式客观权重集合预报方法(简称OBJ)。该方法基于训练期内单个模式的预报结果,用线性回归订正单个预报的偏差,依据模式的预报效果估计单个模式的权重。利用2002年2月—2015年10月美国哥伦比亚大学国际气候与社会研究所(IRI)提供的7个单一模式对NINO3.4指数的预报结果进行OBJ试验,并采用均方根误差对多模式集合平均预报(简称ENS)和OBJ的预报结果进行检验和评估。结果表明,ENS的预报效果优于7个单一模式的预报效果,而OBJ预报效果优于ENS预报效果,其NINO3.4指数的均方根误差比ENS方法降低了4%。将单一模式预报结果按时间划分为训练期和预报期,利用独立样本估计OBJ的参数并进行预报试验,这些试验也表明,OBJ能进一步提高预报精度。展开更多
Abnormal weather conditions and extreme weather existed over the Kingdom Saudi Arabia (KSA) through the last decades. The present paper investigates the relationship between the Oceanic Nino Index (ONI) and variabilit...Abnormal weather conditions and extreme weather existed over the Kingdom Saudi Arabia (KSA) through the last decades. The present paper investigates the relationship between the Oceanic Nino Index (ONI) and variability of surface air temperature and precipitation rate over KSA through the period from 1950 to 2015 year. The NCEP/NCAR Reanalysis of monthly data sets of the mean surface air temperature and precipitation rate for the domain of the KSA is used. In addition, El Nino3.4 monthly data through the period (1950-2015) are used. For that period, the data set of the three months moving average of Nino3.4 anomaly, Oceanic Nino index (ONI), is used and analyzed. The time series, anomaly and correlation coefficient techniques are used to analyze the data sets through the present study. The results revealed that the KSA climate parameters, temperature and precipitation rates are controlled by ONI mainly in the autumn and winter seasons.展开更多
The Walker circulation(WC)has always been an important issue in atmospheric science research due to the association between the WC and tropical Pacific sea surface temperature(SST),and between the WC and ENSO events.I...The Walker circulation(WC)has always been an important issue in atmospheric science research due to the association between the WC and tropical Pacific sea surface temperature(SST),and between the WC and ENSO events.In this paper,a new index-Omega index(OMGI)-is constructed for WC characterization based on the NCEP/NCAR reanalysis data of monthly mean vertical velocity in recent 70 years(1948-2017).Results show that the OMGI can accurately depict the variation characteristics of WC on seasonal,annual and decadal time-scales.There is a significant inverse correlation between the OMGI and equatorial eastern and central Pacific SST.Meanwhile,the peak of the OMGI appears ahead of the ENSO peak,and therefore is able to reflect the SST in the equatorial Pacific.Especially,in 35 ENSO events,the peak of the OMGI appears earlier than Ni?o 3.4 index for 19 times with 2.6 months ahead on average.In 16 El Ni?o events,the peak of the OMGI occurs ahead of the El Ni?o for 9 times with 4 months ahead on average.In19 La Ni?a events,the OMGI peak arises 10 times earlier than the La Ni?a peak,with an average of 1.4 months ahead.OMGI shows obvious leading effect and stability over ENSO events with different strengths and types of single peak and multi peaks:the peak of the OMGI keeps about 2-3 months ahead of the ENSO.Compared with other WC indexes such as UWI and SPLI,OMGI has some advantages in the ability to describe WC changes and present the probability and the time of prediction of ENSO event peaks.展开更多
Objective: To identify the influences of local and regional climate phenomena on dengue transmission in Lahore District of Pakistan, from 2006 to 2014. Methods: Time-series models were applied to analyze associations ...Objective: To identify the influences of local and regional climate phenomena on dengue transmission in Lahore District of Pakistan, from 2006 to 2014. Methods: Time-series models were applied to analyze associations between reported cases of dengue and climatic parameters. The coherence trend of regional climate phenomena(IOD and ENSO) was evaluated with wavelet analysis. Results: The minimum temperature 4 months before the dengue outbreak played the most important role in the Lahore District(P=0.03). A NINO 3.4 index 9 months before the outbreaks exhibited a significant negative effect on dengue transmission(P=0.02). The IOD exhibited a synchronized pattern with dengue outbreak from 2010 to 2012. The ENSO effect(NINO 3.4 index) might have played a more important role after 2012. Conclusions: This study provides preliminary results of climate influences on dengue transmission in the Lahore District of Pakistan. An increasing dengue transmission risk accompanied by frequent climate changes should be noted. Integrating the influences of climate variability into disease prevention strategies should be considered by public health authorities.展开更多
Cluster analysis has been performed on the tracks of 51 Tropical Cyclones （TCs） that made landfall on the Korean Peninsula （KP） for the period of 1951-2004. The classification technique of the landfalling tracks u...Cluster analysis has been performed on the tracks of 51 Tropical Cyclones （TCs） that made landfall on the Korean Peninsula （KP） for the period of 1951-2004. The classification technique of the landfalling tracks used in this study was the fuzzy clustering method （FCM） and the resultant silhouette coefficient suggested four clusters as an optimal cluster number. Most TCs of Cluster 2 and Cluster 3 （C-23） tended to pass through China's Mainland before landfall, but those of Cluster 1 and Cluster 4 （C-14） tended to mostly land after moving northward from the East China Sea （ECS） without passing over China's Mainland. The TC landfalling frequency of C-14 has begun to clearly increase since the late 1980s, particularly the maximum landfalling frequency in the early 2000s set a record for the 54-year analysis period. The ridge axis of the western North Pacific high （WNPH） of C-23 bends more equatorward than that of C-14, so that the monsoon trough of C-23 is located more equatorward than that of C-14. As a consequence, most TCs of C-23 tend to recurve inland of China, but over the ECS for C-14.展开更多
文摘An extreme warming hit Europe in summer of the year 2015. The present paper investigates the relationship between the North Atlantic Oscillation Index (NAO), Southern Oscillation Index (SOI) and El-Nino 3.4 and heat waves that persist over the western and central Europe in the summer of 2015. The NCEP/NCAR Reanalysis daily dataset of the mean surface air temperature for the domains of the western and central Europe for summer months (June, July and August) of the year, 2015 has used. In addition, the time cross-section analysis of the daily gridded operational data for the mean surface air temperature over the western and central Europe from 1 June to 31 August 2015 has done. Moreover, daily datasets of the NAO, SOI, and El-Nino 3.4 for that period have used. The time series, time cross section, anomaly and correlation coefficient techniques are used to analyze the data sets. The results revealed that the cases of heat waves that existed over the western and central Europe through the summer season of the year 2015 were controlled distinctly by the negative phase of the NAO and positive phase of ENSO.
文摘基于贝叶斯模式平均方法(Bayesian Model Averaging),发展了一个NINO3.4指数的多模式客观权重集合预报方法(简称OBJ)。该方法基于训练期内单个模式的预报结果,用线性回归订正单个预报的偏差,依据模式的预报效果估计单个模式的权重。利用2002年2月—2015年10月美国哥伦比亚大学国际气候与社会研究所(IRI)提供的7个单一模式对NINO3.4指数的预报结果进行OBJ试验,并采用均方根误差对多模式集合平均预报(简称ENS)和OBJ的预报结果进行检验和评估。结果表明,ENS的预报效果优于7个单一模式的预报效果,而OBJ预报效果优于ENS预报效果,其NINO3.4指数的均方根误差比ENS方法降低了4%。将单一模式预报结果按时间划分为训练期和预报期,利用独立样本估计OBJ的参数并进行预报试验,这些试验也表明,OBJ能进一步提高预报精度。
文摘Abnormal weather conditions and extreme weather existed over the Kingdom Saudi Arabia (KSA) through the last decades. The present paper investigates the relationship between the Oceanic Nino Index (ONI) and variability of surface air temperature and precipitation rate over KSA through the period from 1950 to 2015 year. The NCEP/NCAR Reanalysis of monthly data sets of the mean surface air temperature and precipitation rate for the domain of the KSA is used. In addition, El Nino3.4 monthly data through the period (1950-2015) are used. For that period, the data set of the three months moving average of Nino3.4 anomaly, Oceanic Nino index (ONI), is used and analyzed. The time series, anomaly and correlation coefficient techniques are used to analyze the data sets through the present study. The results revealed that the KSA climate parameters, temperature and precipitation rates are controlled by ONI mainly in the autumn and winter seasons.
基金National Natural Science Foundation of China(41605043)National Key R&D Program of China(2016YFA0601504)Fundamental Research Funds for the Central Universities(2017B00114)。
文摘The Walker circulation(WC)has always been an important issue in atmospheric science research due to the association between the WC and tropical Pacific sea surface temperature(SST),and between the WC and ENSO events.In this paper,a new index-Omega index(OMGI)-is constructed for WC characterization based on the NCEP/NCAR reanalysis data of monthly mean vertical velocity in recent 70 years(1948-2017).Results show that the OMGI can accurately depict the variation characteristics of WC on seasonal,annual and decadal time-scales.There is a significant inverse correlation between the OMGI and equatorial eastern and central Pacific SST.Meanwhile,the peak of the OMGI appears ahead of the ENSO peak,and therefore is able to reflect the SST in the equatorial Pacific.Especially,in 35 ENSO events,the peak of the OMGI appears earlier than Ni?o 3.4 index for 19 times with 2.6 months ahead on average.In 16 El Ni?o events,the peak of the OMGI occurs ahead of the El Ni?o for 9 times with 4 months ahead on average.In19 La Ni?a events,the OMGI peak arises 10 times earlier than the La Ni?a peak,with an average of 1.4 months ahead.OMGI shows obvious leading effect and stability over ENSO events with different strengths and types of single peak and multi peaks:the peak of the OMGI keeps about 2-3 months ahead of the ENSO.Compared with other WC indexes such as UWI and SPLI,OMGI has some advantages in the ability to describe WC changes and present the probability and the time of prediction of ENSO event peaks.
基金funded by the Taiwan Ministry of Science and Technology(MOST 104-2119-M-038-002)the Taipei Medical University(TMU101-AE1-B62)
文摘Objective: To identify the influences of local and regional climate phenomena on dengue transmission in Lahore District of Pakistan, from 2006 to 2014. Methods: Time-series models were applied to analyze associations between reported cases of dengue and climatic parameters. The coherence trend of regional climate phenomena(IOD and ENSO) was evaluated with wavelet analysis. Results: The minimum temperature 4 months before the dengue outbreak played the most important role in the Lahore District(P=0.03). A NINO 3.4 index 9 months before the outbreaks exhibited a significant negative effect on dengue transmission(P=0.02). The IOD exhibited a synchronized pattern with dengue outbreak from 2010 to 2012. The ENSO effect(NINO 3.4 index) might have played a more important role after 2012. Conclusions: This study provides preliminary results of climate influences on dengue transmission in the Lahore District of Pakistan. An increasing dengue transmission risk accompanied by frequent climate changes should be noted. Integrating the influences of climate variability into disease prevention strategies should be considered by public health authorities.
基金supported by the National Instituteof Meteorological Research (NIMR) in the Korea Meteoro-logical Administration.
文摘Cluster analysis has been performed on the tracks of 51 Tropical Cyclones （TCs） that made landfall on the Korean Peninsula （KP） for the period of 1951-2004. The classification technique of the landfalling tracks used in this study was the fuzzy clustering method （FCM） and the resultant silhouette coefficient suggested four clusters as an optimal cluster number. Most TCs of Cluster 2 and Cluster 3 （C-23） tended to pass through China's Mainland before landfall, but those of Cluster 1 and Cluster 4 （C-14） tended to mostly land after moving northward from the East China Sea （ECS） without passing over China's Mainland. The TC landfalling frequency of C-14 has begun to clearly increase since the late 1980s, particularly the maximum landfalling frequency in the early 2000s set a record for the 54-year analysis period. The ridge axis of the western North Pacific high （WNPH） of C-23 bends more equatorward than that of C-14, so that the monsoon trough of C-23 is located more equatorward than that of C-14. As a consequence, most TCs of C-23 tend to recurve inland of China, but over the ECS for C-14.
