Background:An influenza forecasting system is critical to influenza epidemic preparedness.Low temperature has long been recognized as a condition favoring influenza epidemic,yet it fails to justify the summer influenz...Background:An influenza forecasting system is critical to influenza epidemic preparedness.Low temperature has long been recognized as a condition favoring influenza epidemic,yet it fails to justify the summer influenza peak in tropics/subtropics.Recent studies have suggested that absolute humidity(AH)had a U-shape relationship with influenza survival and transmission across climate zones,indicating that a unified influenza forecasting system could be established for China with various climate conditions.Methods:Our study has generated weekly influenza forecasts by season and type/subtype in northern and southern China from 2011 to 2021,using a forecasting system combining an AH-driven susceptible-infected-recovered-susceptible(SIRS)model and the ensemble adjustment Kalman filter(EAKF).Model performance was assessed by sensitivity and specificity in predicting epidemics,and by accuracies in predicting peak timing and magnitude.Results:Our forecast system can generally well predict seasonal influenza epidemics(mean sensitivity>87.5%;mean specificity>80%).The average forecast accuracies were 82%and 60%for peak timing and magnitude at 3e6 weeks ahead for northern China,higher than those of 42%and 20%for southern China.The accuracy was generally better when the forecast was made closer to the actual peak time.Discussion:The established AH-driven forecasting system can generally well predict the occurrence of seasonal influenza epidemics in China.展开更多
The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and di...The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas.展开更多
Biological experiments and epidemiological evidence indicate that variations in environment have important effect on the occurrence and transmission of epidemic influenza.It is therefore important to understand the ch...Biological experiments and epidemiological evidence indicate that variations in environment have important effect on the occurrence and transmission of epidemic influenza.It is therefore important to understand the characteristic patterns of transmission for prevention of disease and reduction of disease burden.Based on case records,we analyzed the environmental characteristics including climate variables in Changsha,and then constructed a meteorological anomaly susceptive-infective-removal (SIR) model on the basis of the results of influenza A (H1N1) transmission.The results showed that the outbreak of influenza A (H1N1) in Changsha showed significant correlation with meteorological conditions;the spread of influenza was sensitive to meteorological anomalies,and that the outbreak of influenza A (H1N1) in Changsha was influenced by a combination of absolute humidity anomalous weather conditions,contact rates of the influenza patients and changes in population movements.These findings will provide helpful information regarding prevention strategies under different conditions,a fresh understanding of the emergence and re-emergence of influenza outbreaks,and a new perspective on the transmission dynamics of influenza.展开更多
基金supported by the Three-year Public Health System Construction Program of Shanghai,from Shanghai Municipal Health Commission of China[grant number GWV-10.2-YQ36].
文摘Background:An influenza forecasting system is critical to influenza epidemic preparedness.Low temperature has long been recognized as a condition favoring influenza epidemic,yet it fails to justify the summer influenza peak in tropics/subtropics.Recent studies have suggested that absolute humidity(AH)had a U-shape relationship with influenza survival and transmission across climate zones,indicating that a unified influenza forecasting system could be established for China with various climate conditions.Methods:Our study has generated weekly influenza forecasts by season and type/subtype in northern and southern China from 2011 to 2021,using a forecasting system combining an AH-driven susceptible-infected-recovered-susceptible(SIRS)model and the ensemble adjustment Kalman filter(EAKF).Model performance was assessed by sensitivity and specificity in predicting epidemics,and by accuracies in predicting peak timing and magnitude.Results:Our forecast system can generally well predict seasonal influenza epidemics(mean sensitivity>87.5%;mean specificity>80%).The average forecast accuracies were 82%and 60%for peak timing and magnitude at 3e6 weeks ahead for northern China,higher than those of 42%and 20%for southern China.The accuracy was generally better when the forecast was made closer to the actual peak time.Discussion:The established AH-driven forecasting system can generally well predict the occurrence of seasonal influenza epidemics in China.
基金supported by the National Key R&D Program of China(2017YFA0605101)the National Natural Science Foundation of China(31770489,41273098 and 31621091)
文摘The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas.
基金supported by Hunan Provincial Natural Science Foundation of China(11JJ3119)the Key Discipline Construction Project in Hunan Province(2008001)the Scientific Research Fund of Hunan Provincial Education Department(11K037)
文摘Biological experiments and epidemiological evidence indicate that variations in environment have important effect on the occurrence and transmission of epidemic influenza.It is therefore important to understand the characteristic patterns of transmission for prevention of disease and reduction of disease burden.Based on case records,we analyzed the environmental characteristics including climate variables in Changsha,and then constructed a meteorological anomaly susceptive-infective-removal (SIR) model on the basis of the results of influenza A (H1N1) transmission.The results showed that the outbreak of influenza A (H1N1) in Changsha showed significant correlation with meteorological conditions;the spread of influenza was sensitive to meteorological anomalies,and that the outbreak of influenza A (H1N1) in Changsha was influenced by a combination of absolute humidity anomalous weather conditions,contact rates of the influenza patients and changes in population movements.These findings will provide helpful information regarding prevention strategies under different conditions,a fresh understanding of the emergence and re-emergence of influenza outbreaks,and a new perspective on the transmission dynamics of influenza.
