Based on a daily precipitation observation dataset of 743 stations in China from 1951 2004, the F distribution function is used to calculate the probability distribution of daily precipitation and to define extreme pr...Based on a daily precipitation observation dataset of 743 stations in China from 1951 2004, the F distribution function is used to calculate the probability distribution of daily precipitation and to define extreme precipitation events. Based on this, the relationship of ENSO and the frequency of extreme precipitation events is studied. Results reveal that ENSO events have impact on extreme precipitation events, with different magnitudes at different regions and seasons. In general, during winter and spring, extreme precipitation events occur more often during E1 Nino events than during La Nina events. While during summer and autumn, the opposite is found. The relationship of a two season-lag ENSO and extreme precipitation frequency shows different pattern. Extreme precipitation events occur more often in several regions if an ENSO warm phase happened in the central-eastern tropical Pacific two seasons before. No similar impacts of El Nino and La Nina on the frequency of extreme precipitation events are found.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
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
We report the first(to the best of our knowledge) tunable passively Q-switched Er3+-doped ZrF4 fiber laser around 3.5 μm. In this case, a Fe2+:ZnSe crystal is used as the saturable absorber, and a plane-ruled grating...We report the first(to the best of our knowledge) tunable passively Q-switched Er3+-doped ZrF4 fiber laser around 3.5 μm. In this case, a Fe2+:ZnSe crystal is used as the saturable absorber, and a plane-ruled grating in a Littrow configuration acts as the tuning element. At the tuned wavelength of 3478.0 nm, stable Q-switching with a maximum average power of 583.7 mW was achieved with a slope efficiency of 15.2% relative to the launched 1981 nm pump power. Further power scaling is mainly limited by the available 1981 nm pump power. The corresponding pulse width, repetition rate, and pulse energy are 1.18 μs, 71.43 kHz, and 7.54 μJ, respectively. By rotating the grating, the Q-switching can be continuously tuned in the region of 3.4–3.7 μm. To the best of our knowledge, this is the first pulsed rare-earth-doped fiber laser tunable in the region beyond 3.4 μm.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
基金supported by the program under Grant No.2007BAC29B04
文摘Based on a daily precipitation observation dataset of 743 stations in China from 1951 2004, the F distribution function is used to calculate the probability distribution of daily precipitation and to define extreme precipitation events. Based on this, the relationship of ENSO and the frequency of extreme precipitation events is studied. Results reveal that ENSO events have impact on extreme precipitation events, with different magnitudes at different regions and seasons. In general, during winter and spring, extreme precipitation events occur more often during E1 Nino events than during La Nina events. While during summer and autumn, the opposite is found. The relationship of a two season-lag ENSO and extreme precipitation frequency shows different pattern. Extreme precipitation events occur more often in several regions if an ENSO warm phase happened in the central-eastern tropical Pacific two seasons before. No similar impacts of El Nino and La Nina on the frequency of extreme precipitation events are found.
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.
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.
基金National Natural Science Foundation of China(NSFC)(61722503,61421002,61435003)Open Fund of Science and Technology on Solid-State Laser Laboratory+1 种基金Joint Fund of Ministry of Education for Equipment PreResearch(6141A02033411)Field Funding for Equipment Pre-Research(1114180106A)
文摘We report the first(to the best of our knowledge) tunable passively Q-switched Er3+-doped ZrF4 fiber laser around 3.5 μm. In this case, a Fe2+:ZnSe crystal is used as the saturable absorber, and a plane-ruled grating in a Littrow configuration acts as the tuning element. At the tuned wavelength of 3478.0 nm, stable Q-switching with a maximum average power of 583.7 mW was achieved with a slope efficiency of 15.2% relative to the launched 1981 nm pump power. Further power scaling is mainly limited by the available 1981 nm pump power. The corresponding pulse width, repetition rate, and pulse energy are 1.18 μs, 71.43 kHz, and 7.54 μJ, respectively. By rotating the grating, the Q-switching can be continuously tuned in the region of 3.4–3.7 μm. To the best of our knowledge, this is the first pulsed rare-earth-doped fiber laser tunable in the region beyond 3.4 μm.
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.
