scholarly journals A Comprehensive Study of Spatiotemporal Variations in Temperature Extremes across China during 1960–2018

2021 ◽  
Vol 13 (7) ◽  
pp. 3807
Author(s):  
Na Zhao ◽  
Mingxing Chen
Keyword(s):  
Spatial Heterogeneity ◽  
Mainland China ◽  
Kendall Test ◽  
Northern China ◽  
Central China ◽  
Maximum Temperature ◽  
Temperature Extremes ◽  
Northwestern Part ◽  
Spatiotemporal Variations ◽  
Increasing Trends

Understanding the changing patterns of extreme temperatures is important for taking measures to reduce their associated negative impacts. Based on daily temperature data derived from 2272 meteorological stations in China, the spatiotemporal variations in temperature extremes were examined with respect to covariates by means of the Mann–Kendall test and a spatiotemporal model during 1960–2018. The results indicated that the temporal changes in cold extremes showed decreasing trends and warm extremes experienced increasing trends across almost all of China, with mean change rates of −3.9 days, −1.8 days, 3.7 days and 2.3 days per decade for TN10p, TX10p, TN90p and TX90p, respectively. Nighttime warming/cooling was higher than daytime warming/cooling, which indicated that trends in minimum temperature extremes are more rapid than trends in maximum temperature extremes. In addition, the temporal effect on the temperature extremes varied throughout the year, with significant increasing trends in the temporal heterogeneity of warm extremes occurring during 1992–2018. The areas with strong spatial heterogeneity of cool nights mainly included northeastern and central China, and the spatial variation on cool days was more prominent in northern China. For warm nights, the areas showing high spatial heterogeneity were mainly located in the northwestern part of China, while areas for warm days were distributed in northern China. Our results provide meaningful information for a deeper understanding of the spatiotemporal variations in temperature extremes across mainland China.

scholarly journals Observed Trends in Indices of Daily Temperature Extremes in South America 1960–2000

2005 ◽  
Vol 18 (23) ◽  
pp. 5011-5023 ◽  
Author(s):  
L. A. Vincent ◽  
T. C. Peterson ◽  
V. R. Barros ◽  
M. B. Marino ◽  
M. Rusticucci ◽  
...  
Keyword(s):  
Climate Change ◽  
South America ◽  
Climate Extremes ◽  
Daily Temperature ◽  
Maximum Temperature ◽  
Daily Minimum Temperature ◽  
Daily Maximum Temperature ◽  
Daily Maximum ◽  
Temperature Extremes ◽  
Increasing Trends

Abstract A workshop on enhancing climate change indices in South America was held in Maceió, Brazil, in August 2004. Scientists from eight southern countries brought daily climatological data from their region for a meticulous assessment of data quality and homogeneity, and for the preparation of climate change indices that can be used for analyses of changes in climate extremes. This study presents an examination of the trends over 1960–2000 in the indices of daily temperature extremes. The results indicate no consistent changes in the indices based on daily maximum temperature while significant trends were found in the indices based on daily minimum temperature. Significant increasing trends in the percentage of warm nights and decreasing trends in the percentage of cold nights were observed at many stations. It seems that this warming is mostly due to more warm nights and fewer cold nights during the summer (December–February) and fall (March–May). The stations with significant trends appear to be located closer to the west and east coasts of South America.

scholarly journals Modeling precipitation δ<sup>18</sup>O pariability in East Asia since the Last Glacial Maximum: temperature and amount effects across different time scales

2016 ◽  
Author(s):  
Xinyu Wen ◽  
Zhengyu Liu ◽  
Zhongxiao Chen ◽  
Esther Brady ◽  
David Noone ◽  
...  
Keyword(s):  
East Asia ◽  
Temperature Effect ◽  
Southern China ◽  
Northern China ◽  
Point Of View ◽  
Central China ◽  
Maximum Temperature ◽  
Past Climate ◽  
Amount Effect ◽  
Significant Temperature

Abstract. Water isotope in precipitation has played a key role in the reconstruction of past climate on millennial and longer timescales. However, for mid-latitude regions like East Asia with complex terrain, the reliability behind the basic assumptions of the temperature effect and amount effect are based on modern observational data and still remains unclear for past climate. In the present work, we re-examine the two basic effects on seasonal, interannual, and millennial timescales in a set of time slice experiments for the period 22 ka thru 00 ka using an isotope-enable AGCM. Our study confirms the robustness of the temperature and amount effects on the seasonal cycle over China, with the temperature effect dominating in northern China, and the amount effect dominating in deep southern China, but no one distinct in the transition region of central China. However, our analysis does not show significant temperature and amount effects over China on millennial and interannual timescales, which is a challenge to those classic assumptions in past climate reconstruction. Our work helps shed light on the interpretation of the proxy record of δ18O from modeling point of view.

scholarly journals Comparison of spatiotemporal characteristics of the COVID-19 and SARS outbreaks in mainland China

2020 ◽  
Author(s):  
Xi Zhang ◽  
Huaxiang Rao ◽  
Yuwan Wu ◽  
Yubei Huang ◽  
Hongji Dai
Keyword(s):  
Spatial Clustering ◽  
Spatial Association ◽  
Mainland China ◽  
Northern China ◽  
Central China ◽  
Infected People ◽  
Transmission Mechanisms ◽  
South Central ◽  
Temporal Features ◽  
Spatiotemporal Clustering

Abstract Background: Both coronavirus disease 2019 (COVID-19) and severe acute respiratory syndrome (SARS) are caused by coronaviruses and have infected people in China and worldwide. We aimed to investigate whether COVID-19 and SARS exhibited similar spatial and temporal features at provincial level in mainland China.Methods: The number of people infected by COVID-19 and SARS were extracted from daily briefings on newly confirmed cases during the epidemics, as of Mar. 4, 2020 and Aug. 3, 2003, respectively. We depicted spatiotemporal patterns of the COVID-19 and SARS epidemics using spatial statistics such as Moran’s I and the local indicators of spatial association (LISA).Results: Compared to SARS, COVID-19 had a higher overall incidence. We identified 3 clusters (predominantly located in south-central China; the highest RR=135.08, 95% CI: 128.36-142.08) for COVID-19 and 4 clusters (mainly in Northern China; the highest RR=423.51, 95% CI: 240.96-722.32) for SARS. Fewer secondary clusters were identified after the "Wuhan lockdown". The LISA cluster map detected a significantly high-low (Hubei) and low-high spatial clustering (Anhui, Hunan, and Jiangxi, in Central China) for COVID-19. Two significant high-high (Beijing and Tianjin) and low-high (Hebei) clusters were detected for SARS.Conclusions: COVID-19 and SARS outbreaks exhibited distinct spatiotemporal clustering patterns at the provincial levels in mainland China, which may be attributable to changes in social and demographic factors, local government containment strategies or differences in transmission mechanisms.

scholarly journals Comparison of spatiotemporal characteristics of the COVID-19 and SARS outbreaks in mainland China

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Xi Zhang ◽  
Huaxiang Rao ◽  
Yuwan Wu ◽  
Yubei Huang ◽  
Hongji Dai
Keyword(s):  
Spatial Clustering ◽  
Spatial Association ◽  
Mainland China ◽  
Northern China ◽  
Central China ◽  
Infected People ◽  
Transmission Mechanisms ◽  
South Central ◽  
Temporal Features ◽  
Spatiotemporal Clustering

Abstract Background Both coronavirus disease 2019 (COVID-19) and severe acute respiratory syndrome (SARS) are caused by coronaviruses and have infected people in China and worldwide. We aimed to investigate whether COVID-19 and SARS exhibited similar spatial and temporal features at provincial level in mainland China. Methods The number of people infected by COVID-19 and SARS were extracted from daily briefings on newly confirmed cases during the epidemics, as of Mar. 4, 2020 and Aug. 3, 2003, respectively. We depicted spatiotemporal patterns of the COVID-19 and SARS epidemics using spatial statistics such as Moran’s I and the local indicators of spatial association (LISA). Results Compared to SARS, COVID-19 had a higher overall incidence. We identified 3 clusters (predominantly located in south-central China; the highest RR = 135.08, 95% CI: 128.36–142.08) for COVID-19 and 4 clusters (mainly in Northern China; the highest RR = 423.51, 95% CI: 240.96–722.32) for SARS. Fewer secondary clusters were identified after the “Wuhan lockdown”. The LISA cluster map detected a significantly high-low (Hubei) and low-high spatial clustering (Anhui, Hunan, and Jiangxi, in Central China) for COVID-19. Two significant high-high (Beijing and Tianjin) and low-high (Hebei) clusters were detected for SARS. Conclusions COVID-19 and SARS outbreaks exhibited distinct spatiotemporal clustering patterns at the provincial levels in mainland China, which may be attributable to changes in social and demographic factors, local government containment strategies or differences in transmission mechanisms.

scholarly journals Observational evidence of climate change on extreme events over East Africa

2013 ◽  
Vol 2 (1) ◽  
pp. 2 ◽  
Author(s):  
Joshua Ngaina ◽  
Bethwel Mutai
Keyword(s):  
Climate Change ◽  
East Africa ◽  
Extreme Values ◽  
Southern Oscillation ◽  
Kendall Test ◽  
Significant Rise ◽  
Maximum Temperature ◽  
Sunspot Activity ◽  
Temperature Extremes ◽  
Time Pattern

Examination of trend patterns of rainfall and temperature extremes over East Africa (EA) was based on graphical, regression and Mann-Kendall test approaches, while perturbations of rainfall, sunspot activity (SA) and southern oscillation index (SOI) extremes were computed using moving average methods. Annual total rainfall generally decreased with heavy and extreme precipitation rates confined within short spells during wet days. Observed maximum temperature extremes increased while minimum temperature extremes decreased with a statistically significant rise in the number of hot days and warm nights and a decrease in number of cool days and cold nights. However, space-time pattern of observed changes were not well organized. Perturbations of rainfall, SA and SOI indicated that extreme values were changing with increasing frequency and magnitude. Similarities in observed rainfall over EA illustrated the existence of homogeneous zones of climate change clustered as either coastal (with SA dominant), lake Victoria (unique to both SA and SOI), dry continental (SOI) or wet continental areas (both SA and SOI dominant).

scholarly journals Maximum and Minimum Temperature Trends Variation over Northern and Southern Part of Bangladesh

2015 ◽  
Vol 6 (2) ◽  
pp. 83-88 ◽  
Author(s):  
NM Refat Nasher ◽  
MN Uddin
Keyword(s):  
Minimum Temperature ◽  
Geographical Location ◽  
Kendall Test ◽  
Maximum Temperature ◽  
Coastal City ◽  
Post Monsoon ◽  
Temperature Trends ◽  
Two Cities ◽  
Slope Estimator ◽  
Increasing Trends

Temperature is one of the pivotal climatic variables in our world climate literature. In the present study monthly, seasonal and yearly highest maximum and lowest minimum temperatures of two cities were analyzed. Mann-Kendall test and Sen’s Slope Estimator were used to determine the trend and slope magnitude. Chittagong, as the coastal city and Rajshahi, as Barind track were selected as a study area due to its respective geographical location. Such types of data of 52 years for Chittagong as well as 48 years for Rajshahi were collected from Bangladesh Meteorological Department (BMD). Monthly highest maximum and lowest minimum temperature data from 1950-2002 for Chittagong and 1964-2012 for Rajshahi were used for analysis. In Rajshahi, significant rising trends were found in highest maximum post-monsoon temperature, lowest minimum monsoon temperature and highest maximum temperature from July to October, June and August for lowest minimum temperature. Falling trends were found in annual highest maximum and lowest minimum temperatures, pre-monsoon highest maximum temperature, lowest minimum winter temperature and January lowest minimum temperature. For Chittagong, significant increasing trends found in post-monsoon highest maximum temperature, June to December highest maximum temperature except July and December lowest minimum temperature. No significant decreasing trend was found in Chittagong.DOI: http://dx.doi.org/10.3329/jesnr.v6i2.22101 J. Environ. Sci. & Natural Resources, 6(2): 83-88 2013

scholarly journals Comparison of spatiotemporal characteristics of the COVID-19 and SARS outbreaks in mainland China

2020 ◽  
Author(s):  
Xi Zhang ◽  
Huaxiang Rao ◽  
Yuwan Wu ◽  
Yubei Huang ◽  
Hongji Dai
Keyword(s):  
Spatial Clustering ◽  
Spatial Association ◽  
Mainland China ◽  
Northern China ◽  
Central China ◽  
Infected People ◽  
Transmission Mechanisms ◽  
South Central ◽  
Temporal Features ◽  
Spatiotemporal Clustering

Abstract Background: Both coronavirus disease 2019 (COVID-19) and severe acute respiratory syndrome (SARS) are caused by coronaviruses and have infected people in China and worldwide. We aimed to investigate whether COVID-19 and SARS exhibited similar spatial and temporal features at provincial level in mainland China.Methods: The number of people infected by COVID-19 and SARS were extracted from daily briefings on newly confirmed cases during the epidemics, as of Mar. 4, 2020 and Aug. 3, 2003, respectively. We depicted spatiotemporal patterns of the COVID-19 and SARS epidemics using spatial statistics such as Moran’s I and the local indicators of spatial association (LISA).Results: Compared to SARS, COVID-19 had a higher overall incidence. We identified 3 clusters (predominantly located in south-central China; the highest RR=135.08, 95% CI: 128.36-142.08) for COVID-19 and 4 clusters (mainly in Northern China; the highest RR=423.51, 95% CI: 240.96-722.32) for SARS. Fewer secondary clusters were identified after the "Wuhan lockdown". The LISA cluster map detected a significantly high-low (Hubei) and low-high spatial clustering (Anhui, Hunan, and Jiangxi, in Central China) for COVID-19. Two significant high-high (Beijing and Tianjin) and low-high (Hebei) clusters were detected for SARS.Conclusions: COVID-19 and SARS outbreaks exhibited distinct spatiotemporal clustering patterns at the provincial levels in mainland China, which may be attributable to changes in social and demographic factors, local government containment strategies or differences in transmission mechanisms.

scholarly journals Water quality trend analysis of Cheurfas II dam, Algeria

2021 ◽  
Author(s):  
Salima Rezak ◽  
Farid Rahal ◽  
Abdellah Bahmani
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Surface Waters ◽  
Temporal Evolution ◽  
Kendall Test ◽  
Organic Pollution ◽  
Water Volume ◽  
Northwestern Part ◽  
Different Origins ◽  
Increasing Trends

The northwestern part of Algeria is characterized by a semi-arid climate which has created semi-permanent rivers and dams with low filling rates. It is important to preserve the water resource, which is becoming increasingly scarce. Additionally, it is worth indicating that the mobilized surface waters are continually under threat of significant organic pollution. Indeed, the dam of Cheurfas II, in the northwestern part of the country, is indicative of this situation. In order to establish a diagnosis of the state of the temporal evolution of water quality, time series of 11 variables indicating the presence of organic pollution in this dam were thus analyzed. The data collected were analyzed using the Mann-Kendall test to look for significant trends and the Webel-Ollech test to detect the presence of seasonality. The results obtained showed increasing trends in dry residues, organic matter, phosphates and dissolved oxygen. However, variables like BOD5, COD and NO-3 showed decreasing trends. As for the variables NH+4, NO-2 and pH, they presented no trend. Finally, the water volume of the dam exhibited a significant increase. In addition, no seasonality was detected in the variables studied, with the exception of the PO43- time series and water volume. These findings indicate that the watershed of the dam received pollutants from different origins, in particular industrial pollutants. This makes water biodegradability difficult to achieve.

scholarly journals Modeling precipitation <i>δ</i><sup>18</sup>O variability in East Asia since the Last Glacial Maximum: temperature and amount effects across different timescales

2016 ◽  
Vol 12 (11) ◽  
pp. 2077-2085 ◽  
Author(s):  
Xinyu Wen ◽  
Zhengyu Liu ◽  
Zhongxiao Chen ◽  
Esther Brady ◽  
David Noone ◽  
...  
Keyword(s):  
East Asia ◽  
Temperature Effect ◽  
General Circulation ◽  
Circulation Model ◽  
Northern China ◽  
Climatic Conditions ◽  
Central China ◽  
Maximum Temperature ◽  
Past Climate ◽  
Amount Effect

Abstract. Water isotopes in precipitation have played a key role in the reconstruction of past climate on millennial timescales and longer. However, for midlatitude regions like East Asia with complex terrain, the reliability behind the basic assumptions of the temperature effect and amount effect is based on modern observational data and still remains unclear for past climate. In the present work, we reexamine the two basic effects on seasonal, interannual, and millennial timescales in a set of time slice experiments for the period 22–0 ka using an isotope-enabled atmospheric general circulation model (AGCM). Our study confirms the robustness of the temperature and amount effects on the seasonal cycle over China in the present climatic conditions, with the temperature effect dominating in northern China and the amount effect dominating in the far south of China but no distinct effect in the transition region of central China. However, our analysis shows that neither temperature nor amount effect is significantly dominant over China on millennial and interannual timescales, which is a challenge to those classic assumptions in past climate reconstruction. Our work helps shed light on the interpretation of the proxy record of δ18O from a modeling point of view.

Comparative study of multiple heat indices in revisiting summer heat across China based on meteorological observations

2021 ◽  
pp. 030913332110571
Author(s):  
Yao Feng ◽  
Hong Wang ◽  
Wenbin Liu ◽  
Fubao Sun ◽  
Huijuan Cui
Keyword(s):  
Tibetan Plateau ◽  
Comparative Study ◽  
Absolute Threshold ◽  
Northern China ◽  
Heat Index ◽  
Maximum Temperature ◽  
The Tibetan Plateau ◽  
Summer Heat ◽  
Heat Indices ◽  
Increasing Trends

Multiple indices have been created to measure hot conditions that may cause discomfort, stress even death to humans. However, distinctions among these indices and their performance in measuring heat remain undisclosed. We conduct a comparative study of multiple heat indices and revisit the spatiotemporal changes in summer heat across China. The maximum temperature-based index, more sensitive to average and maximum temperatures, suggests a larger increasing trend (0.42°C/10a) in heat intensity than those average temperature-based ones which are more sensitive to minimum temperature. The absolute threshold-based heat-day indices are not so applicable as the relative ones in measuring the increasing heat days over the Tibetan Plateau. During 1960–2018, significant ( p < 0.05) increasing trends in heat intensity (0.11–0.42°C/10a) and heat day (0.63–2.67 days/10a) are revealed with a jump-like increase after the mid-1990s at the country level. Stronger heat intensity occurs over the southeast and north China with larger increasing trends over the Tibetan Plateau and northwest China. Northern China with larger increasing heat intensity and days should take effective measures of adaptation to reduce suffering from the summer heat. Given differences among multiple indices and the performance over different regions, a rational selection of heat index considering the research subject of interest and regional climatology is highly recommended.

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