通过对近百年 El Nino/ L a Nina事件与北京气候相关性研究发现 ,El Nino/ L aNina事件与北京夏季 ( 6~ 8月 )降水、平均最高气温 ( 7月 )和冬季 ( 1月 )平均最低气温之间相互关系显著。 El Nino事件与夏季降水、冬季平均最低气温呈负...通过对近百年 El Nino/ L a Nina事件与北京气候相关性研究发现 ,El Nino/ L aNina事件与北京夏季 ( 6~ 8月 )降水、平均最高气温 ( 7月 )和冬季 ( 1月 )平均最低气温之间相互关系显著。 El Nino事件与夏季降水、冬季平均最低气温呈负相关 ,与夏季平均最高气温呈正相关 ,造成降水减少 ,气温年较差增大 ,大陆性增强的气候特点。L a Nina事件与夏季降水、冬季平均最低气温呈正相关 ,与夏季平均最高气温呈负相关 ,使降水增加 ,气温年较差减小 。展开更多
This study presents a detailed analysis of the asymmetric relationships between the warm/cold phase of the El Ni?o–Southern Oscillation and the typical flood/drought years in summer over Chongqing.Furthermore,its und...This study presents a detailed analysis of the asymmetric relationships between the warm/cold phase of the El Ni?o–Southern Oscillation and the typical flood/drought years in summer over Chongqing.Furthermore,its underpinning mechanisms are also explored.The results show that:(1)El Ni?o and La Ni?a have an asymmetric influence on summer precipitation in the following year over Chongqing.Generally,the composite atmospheric circulation anomalies for El Ni?o years are consistent with the composite results for typical flood years in summer over Chongqing,which indicates a tight link between typical flood years in summer over Chongqing and El Ni?o events.However,the relationship between typical drought years in summer over Chongqing and La Ni?a events is not significant.(2)From winter to the following summer,the extent of positive SST anomalies in the equatorial eastern Pacific associated with typical flood years in summer over Chongqing shrinks,whereas in the tropical Indian Ocean,the extent slightly expands.This trend indicates that the impact of El Ni?o on typical flood years in summer over Chongqing is maintained through the‘relay effect’of SSTs in the tropical Indian Ocean,which is the result of a lagged response of positive SST anomalies in the tropical Indian Ocean to El Ni?o events in winter.展开更多
The Banda Sea is one of the routes of global ocean currents that move from the Pacific Ocean to the Indian Ocean.This flow is known as Indonesian Through Flow(ITF).The Banda Sea is an area where warm and cold water ma...The Banda Sea is one of the routes of global ocean currents that move from the Pacific Ocean to the Indian Ocean.This flow is known as Indonesian Through Flow(ITF).The Banda Sea is an area where warm and cold water masses meet,so it has the potential for a thermal front.This study aims to understand the variability of thermal front in the Banda Sea during the El Nino Southern Oscillation period.Southern Oscillation Index(SOI)and sea surface temperature(SST)data in 2010,2012 and 2015 were used in this study.SOI data was obtained from http://www.bom.gov.au and SST data were obtained from http://oceancolor.gsfc.nasa.gov.The data were processed using ArcGIS 10.4 software and Ms.Office 2013.The results showed the La Nina period occurs in July-December 2010,the Normal period occurs in July-December 2012,and the El Nino period occurs in May-October 2015.In general,during La Nina,the mean SST has higher values than the other periods.On the other hand,the highest thermal front occurs during the El Niño period(10584),followed by the Normal period(7544)and the lowest during the La Niña period(5961),respectively.展开更多
-By using the sea surface temperature (SST) index of the Equatorial Pacific Ocean provided by Climate Analysis Center of U. S. A. , the numerical criteria of El Nino and La Nina events and their quantitative character...-By using the sea surface temperature (SST) index of the Equatorial Pacific Ocean provided by Climate Analysis Center of U. S. A. , the numerical criteria of El Nino and La Nina events and their quantitative characteristics were calculated. Results show that the El Nino event was characterized with strong intensity, shorter life cycle and significant mature phase; however, the La Nina event has longer live cycle, weak intensity, insignificant mature phase. Through teleconnection analysis, it is found that the intensity index of SST over the Equatorial Pacific Ocean leads the intensity index of subtropical high by six months or so. During the El Nino years, the tropical cyclone over the northwestern Pacific is fewer than normal but stronger, and its genesis area shifts southeastward apparently; while in the La Nina years the number of tropical cyclones are larger.展开更多
The analyses on the responses of partial pressure difference between sea and air (PCO2), and total dissolved CO2 concentration (TCO2), to abnormal air-sea event in different seasons, were based on observational data m...The analyses on the responses of partial pressure difference between sea and air (PCO2), and total dissolved CO2 concentration (TCO2), to abnormal air-sea event in different seasons, were based on observational data measured during cruises from Nov. 1986 to Dec 1997 in area of 22°N - 18°N, 114°E-130°E. The results indicated that in every season, TCO2 was high and PCO2 was positive during onset and mature period of El Nino, but they were low and negative respectively during La Nina. Before and after El Nino, partial pressure of CO2 in the sea and air were in the state of equilibrium. Both PCO2 (air) and PCO2 (air) had same responses to E1 Nino in each season. PCO2 (air) and PCO2 (sw) were high during mature period of El Nino were low before and in onset period of El Nino PCO2 and PCO2 (sw) reached peak value during E1 Nino and variation of PCO2 and PCO2 (sw) were same The mean exchange of CO2 from sea to air (flux) reached peak value during El Nino in autumn, and decreased during La Nina. Before and after El Nino the flux is weak, but in opposite direction from air to sea. According to the 1986-1993 average the characteristics of response of TCO2 anomaly to El Nino and La Nina and the range of outstanding variation in different season were discussed. From above it can be deduced some signals showing ENSO event as follows: in Oct.1995, El Nino of 91/95 was over: In May 1995 it is before a new El Nino: In July 1997 it is in onset of new El Nino; In Dec.1997 it is in the mature stage of E1 Nino event.展开更多
Objective:To explore the relationship between climate variables and enteric fever in the city of Ahmedabad and report preliminary findings regarding the influence of El Nino Southern Oscillations and Indian Ocean Dipo...Objective:To explore the relationship between climate variables and enteric fever in the city of Ahmedabad and report preliminary findings regarding the influence of El Nino Southern Oscillations and Indian Ocean Dipole over enteric fever incidence.Method:A total of 29808 Widal positive enteric fever cases reported by the Ahmedabad Municipal Corporation and local climate data in 1985-2017 from Ahmedabad Meteorology Department were analysed.El Nino,La Nina,neutral and Indian Ocean Dipole years as reported by the National Oceanic and Atmospheric Administration for the same period were compared for the incidence of enteric fever.Results:Population-normalized average monthly enteric fever case rates were the highest for El Nino years(25.5),lower for La Nina years(20.5)and lowest for neutral years(17.6).A repeated measures ANOVA analysis showed no significant difference in case rates during the three yearly El Nino Southern Oscillations categories.However,visual profile plot of estimated marginal monthly means showed two distinct characteristics:an early rise and peaking of cases in the El Nino and La Nina years,and a much more restrained rise without conspicuous peaks in neutral years.Further analysis based on monthly El Nino Southern Oscillations categories was conducted to detect differences in median monthly case rates.Median case rates in strong and moderate El Nino months and strong La Nina months were significantly dissimilar from that during neutral months(P<0.001).Conclusions:El Nino Southern Oscillations events influence the incidence of enteric fever cases in Ahmedabad,and further investigation from more cities and towns is required.展开更多
The El Nino Index, defined as 4 intensities (very strong, strong, moderate, weak) in Oceanic Niño Index (ONI), was positively correlated with the average sunspot number at each intensity. The La Niña...The El Nino Index, defined as 4 intensities (very strong, strong, moderate, weak) in Oceanic Niño Index (ONI), was positively correlated with the average sunspot number at each intensity. The La Niña Index, defined as 3 intensities (strong, moderate, weak) in ONI, was negatively correlated with the average sunspot number from 1954 to 2017. It appears that very strong El Niño events occur frequently during the maximal sunspot number while strong La Niña events more often occur during the minimal sunspot number. Since greenhouse-gas is continuously increased, it is therefore proposed that the maximal sunspot number is a major parameter for prediction of El Niño while the minimal sunspot number applies in the same way for La Niña. El Nino/La Nina events can be classified as four typical cases depending upon the submarine volcanic activities at seamounts in Antarctica and South America. The Sea Surface Temperature (SST) of the South and Central Americas are warmer than SST of East Australian Current (EAC), due to the strong volcanic eruptions in the Seamounts and the Ridges in South and Central Americas. This results in the Central Pacific Current (CPC) flowing from east to west due to the second law of thermodynamics for thermal flow from hot source to cold sink. In contrast the opposite direction is made if SST in EAC is warmer than SST in the Central/South American Seamounts and Ridges, due to the strong volcanic eruptions in the Antarctic Seamounts and Ridges. Chicago was selected as a case study for the relationship between extreme cold weather conditions and minimal sunspot number. Previous attempts at predicting weather patterns in Chicago have largely failed. The years of the record low temperatures in Chicago were significantly correlated with the years of the minimal sunspot number from 1873 to 2019. It is forecast that there may occur a weak La Niña in 2019 and another record low temperature in Chicago in January of 2020 due to the phase of the minimal sunspot number in 2019. It may be possible to predict very strong El Nino events with the year of maximal sunspot number as El Niño Index (R2 = 0.7363) and the years of strong volcanic eruption in the Galapagos Hot Spot (GHS) (R2 = 0.9939), respectively. An El Niño event is thus expected during the year of strong volcanic eruption in the GHS. Strong La Niña events can be expected during the year of minimal sunspot number with La Niña Index (R2 = 0.9922). Record low temperatures in Chicago can be also predicted (R2 = 0.9995) during the year of the minimal sunspot number, as was recently the case in January, 2019.展开更多
Geophysical signals N of interest are often contained in a parent signal G that also contains a seasonal signal X at a known frequency fX. The general issues associated with identifying N and X and their separation fr...Geophysical signals N of interest are often contained in a parent signal G that also contains a seasonal signal X at a known frequency fX. The general issues associated with identifying N and X and their separation from G are considered for the case where G is the Pacific sea surface temperature monthly data, SST3.4;N is the El Ni?o/La Ni?a phenomenon and the seasonal signal X is at a frequency of 1/(12 months). It is shown that the commonly used climatology method of subtracting the average seasonal values of SST3.4 to produce the widely used anomaly index Nino3.4 is shown not to remove the seasonal signal. Furthermore, it is shown that the climatology method will always fail. An alternative method is presented in which a 1/fX (= 12 months) moving average filter F is applied to SST3.4 to generate an El Ni?o/La Ni?a index NL that does not contain a seasonal signal. Comparison of NL and Nino3.4 shows, among other things, that estimates of the relative magnitudes of El Ni?os from index NL agree with observations but estimates from index Nino3.4 do not. These results are applicable to other geophysical measurements.展开更多
基金This research was financially supported by the General Project of Technical Innovation and Application Demonstration in Chongqing,China[grant number cstc2018jscx-msybX0165]the Special Fund for the Development of Key Technology in Weather Forecasting of the China Meteorological Administration[grant number YBGJXM(2018)04-08]the National Natural Science Foundation of China[grant number 41875111].
文摘This study presents a detailed analysis of the asymmetric relationships between the warm/cold phase of the El Ni?o–Southern Oscillation and the typical flood/drought years in summer over Chongqing.Furthermore,its underpinning mechanisms are also explored.The results show that:(1)El Ni?o and La Ni?a have an asymmetric influence on summer precipitation in the following year over Chongqing.Generally,the composite atmospheric circulation anomalies for El Ni?o years are consistent with the composite results for typical flood years in summer over Chongqing,which indicates a tight link between typical flood years in summer over Chongqing and El Ni?o events.However,the relationship between typical drought years in summer over Chongqing and La Ni?a events is not significant.(2)From winter to the following summer,the extent of positive SST anomalies in the equatorial eastern Pacific associated with typical flood years in summer over Chongqing shrinks,whereas in the tropical Indian Ocean,the extent slightly expands.This trend indicates that the impact of El Ni?o on typical flood years in summer over Chongqing is maintained through the‘relay effect’of SSTs in the tropical Indian Ocean,which is the result of a lagged response of positive SST anomalies in the tropical Indian Ocean to El Ni?o events in winter.
文摘The Banda Sea is one of the routes of global ocean currents that move from the Pacific Ocean to the Indian Ocean.This flow is known as Indonesian Through Flow(ITF).The Banda Sea is an area where warm and cold water masses meet,so it has the potential for a thermal front.This study aims to understand the variability of thermal front in the Banda Sea during the El Nino Southern Oscillation period.Southern Oscillation Index(SOI)and sea surface temperature(SST)data in 2010,2012 and 2015 were used in this study.SOI data was obtained from http://www.bom.gov.au and SST data were obtained from http://oceancolor.gsfc.nasa.gov.The data were processed using ArcGIS 10.4 software and Ms.Office 2013.The results showed the La Nina period occurs in July-December 2010,the Normal period occurs in July-December 2012,and the El Nino period occurs in May-October 2015.In general,during La Nina,the mean SST has higher values than the other periods.On the other hand,the highest thermal front occurs during the El Niño period(10584),followed by the Normal period(7544)and the lowest during the La Niña period(5961),respectively.
文摘-By using the sea surface temperature (SST) index of the Equatorial Pacific Ocean provided by Climate Analysis Center of U. S. A. , the numerical criteria of El Nino and La Nina events and their quantitative characteristics were calculated. Results show that the El Nino event was characterized with strong intensity, shorter life cycle and significant mature phase; however, the La Nina event has longer live cycle, weak intensity, insignificant mature phase. Through teleconnection analysis, it is found that the intensity index of SST over the Equatorial Pacific Ocean leads the intensity index of subtropical high by six months or so. During the El Nino years, the tropical cyclone over the northwestern Pacific is fewer than normal but stronger, and its genesis area shifts southeastward apparently; while in the La Nina years the number of tropical cyclones are larger.
文摘The analyses on the responses of partial pressure difference between sea and air (PCO2), and total dissolved CO2 concentration (TCO2), to abnormal air-sea event in different seasons, were based on observational data measured during cruises from Nov. 1986 to Dec 1997 in area of 22°N - 18°N, 114°E-130°E. The results indicated that in every season, TCO2 was high and PCO2 was positive during onset and mature period of El Nino, but they were low and negative respectively during La Nina. Before and after El Nino, partial pressure of CO2 in the sea and air were in the state of equilibrium. Both PCO2 (air) and PCO2 (air) had same responses to E1 Nino in each season. PCO2 (air) and PCO2 (sw) were high during mature period of El Nino were low before and in onset period of El Nino PCO2 and PCO2 (sw) reached peak value during E1 Nino and variation of PCO2 and PCO2 (sw) were same The mean exchange of CO2 from sea to air (flux) reached peak value during El Nino in autumn, and decreased during La Nina. Before and after El Nino the flux is weak, but in opposite direction from air to sea. According to the 1986-1993 average the characteristics of response of TCO2 anomaly to El Nino and La Nina and the range of outstanding variation in different season were discussed. From above it can be deduced some signals showing ENSO event as follows: in Oct.1995, El Nino of 91/95 was over: In May 1995 it is before a new El Nino: In July 1997 it is in onset of new El Nino; In Dec.1997 it is in the mature stage of E1 Nino event.
基金funded by Public Health Research Initiative(PHRI)Research grant awarded by PHFI with the financial support of Department of Science and Technology(No.PHRI LN0019).
文摘Objective:To explore the relationship between climate variables and enteric fever in the city of Ahmedabad and report preliminary findings regarding the influence of El Nino Southern Oscillations and Indian Ocean Dipole over enteric fever incidence.Method:A total of 29808 Widal positive enteric fever cases reported by the Ahmedabad Municipal Corporation and local climate data in 1985-2017 from Ahmedabad Meteorology Department were analysed.El Nino,La Nina,neutral and Indian Ocean Dipole years as reported by the National Oceanic and Atmospheric Administration for the same period were compared for the incidence of enteric fever.Results:Population-normalized average monthly enteric fever case rates were the highest for El Nino years(25.5),lower for La Nina years(20.5)and lowest for neutral years(17.6).A repeated measures ANOVA analysis showed no significant difference in case rates during the three yearly El Nino Southern Oscillations categories.However,visual profile plot of estimated marginal monthly means showed two distinct characteristics:an early rise and peaking of cases in the El Nino and La Nina years,and a much more restrained rise without conspicuous peaks in neutral years.Further analysis based on monthly El Nino Southern Oscillations categories was conducted to detect differences in median monthly case rates.Median case rates in strong and moderate El Nino months and strong La Nina months were significantly dissimilar from that during neutral months(P<0.001).Conclusions:El Nino Southern Oscillations events influence the incidence of enteric fever cases in Ahmedabad,and further investigation from more cities and towns is required.
基金the University of Suwon and G-Land of South Korea for their financial supports.
文摘The El Nino Index, defined as 4 intensities (very strong, strong, moderate, weak) in Oceanic Niño Index (ONI), was positively correlated with the average sunspot number at each intensity. The La Niña Index, defined as 3 intensities (strong, moderate, weak) in ONI, was negatively correlated with the average sunspot number from 1954 to 2017. It appears that very strong El Niño events occur frequently during the maximal sunspot number while strong La Niña events more often occur during the minimal sunspot number. Since greenhouse-gas is continuously increased, it is therefore proposed that the maximal sunspot number is a major parameter for prediction of El Niño while the minimal sunspot number applies in the same way for La Niña. El Nino/La Nina events can be classified as four typical cases depending upon the submarine volcanic activities at seamounts in Antarctica and South America. The Sea Surface Temperature (SST) of the South and Central Americas are warmer than SST of East Australian Current (EAC), due to the strong volcanic eruptions in the Seamounts and the Ridges in South and Central Americas. This results in the Central Pacific Current (CPC) flowing from east to west due to the second law of thermodynamics for thermal flow from hot source to cold sink. In contrast the opposite direction is made if SST in EAC is warmer than SST in the Central/South American Seamounts and Ridges, due to the strong volcanic eruptions in the Antarctic Seamounts and Ridges. Chicago was selected as a case study for the relationship between extreme cold weather conditions and minimal sunspot number. Previous attempts at predicting weather patterns in Chicago have largely failed. The years of the record low temperatures in Chicago were significantly correlated with the years of the minimal sunspot number from 1873 to 2019. It is forecast that there may occur a weak La Niña in 2019 and another record low temperature in Chicago in January of 2020 due to the phase of the minimal sunspot number in 2019. It may be possible to predict very strong El Nino events with the year of maximal sunspot number as El Niño Index (R2 = 0.7363) and the years of strong volcanic eruption in the Galapagos Hot Spot (GHS) (R2 = 0.9939), respectively. An El Niño event is thus expected during the year of strong volcanic eruption in the GHS. Strong La Niña events can be expected during the year of minimal sunspot number with La Niña Index (R2 = 0.9922). Record low temperatures in Chicago can be also predicted (R2 = 0.9995) during the year of the minimal sunspot number, as was recently the case in January, 2019.
文摘Geophysical signals N of interest are often contained in a parent signal G that also contains a seasonal signal X at a known frequency fX. The general issues associated with identifying N and X and their separation from G are considered for the case where G is the Pacific sea surface temperature monthly data, SST3.4;N is the El Ni?o/La Ni?a phenomenon and the seasonal signal X is at a frequency of 1/(12 months). It is shown that the commonly used climatology method of subtracting the average seasonal values of SST3.4 to produce the widely used anomaly index Nino3.4 is shown not to remove the seasonal signal. Furthermore, it is shown that the climatology method will always fail. An alternative method is presented in which a 1/fX (= 12 months) moving average filter F is applied to SST3.4 to generate an El Ni?o/La Ni?a index NL that does not contain a seasonal signal. Comparison of NL and Nino3.4 shows, among other things, that estimates of the relative magnitudes of El Ni?os from index NL agree with observations but estimates from index Nino3.4 do not. These results are applicable to other geophysical measurements.