scholarly journals Regionalization and Spatiotemporal Variation of Drought in China Based on Standardized Precipitation Evapotranspiration Index (1961–2013)

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
Xiongfei Liu ◽  
Shixin Wang ◽  
Yi Zhou ◽  
Futao Wang ◽  
Wenjun Li ◽  
...  
Keyword(s):  
Southern China ◽  
Central China ◽  
Tibet Plateau ◽  
Severe Drought ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Spatiotemporal Variations ◽  
Drought Duration ◽  
Mk Test ◽  
Tree Edge ◽  
Edge Removal

China is considered to be one of the most drought prone countries. This study is dedicated to analyzing the regionalization and spatiotemporal variations of drought based on the Standardized Precipitation Evapotranspiration Index, which covers the period 1961–2013 across 810 stations in China. Using Spatial “K”luster Analysis by Tree Edge Removal method, China was divided into eight regions: southwest (SW), northeast (NE), north (N), southeast (SE), Yangtze River (YR), northwest (NW), central China (C), and Tibet Plateau (TP). The spatiotemporal variations of drought characteristics indicated that the drought count in NE and C was generally high. Southern China and NW had suffered long drought duration and extreme severity. The MK test results show that stations with significant drying trends mainly locate in SW, N, NW, and C. The severe drought frequency was very high in 1990s and 2000s. Furthermore, more attention should be paid to abnormal less precipitation in summer and abnormal high temperature in spring in SW, NE, N, and C. Besides, abnormal less precipitation is the main factor of drought in SE and YR in whole year. This study is anticipated to support the water resources management, and to promote the realization of environmental protection and agricultural production.

scholarly journals Exploring the Evolution of Drought Characteristics in Balochistan, Pakistan

2020 ◽  
Vol 10 (3) ◽  
pp. 913 ◽  
Author(s):  
Shoaib Jamro ◽  
Falak Naz Channa ◽  
Ghulam Hussain Dars ◽  
Kamran Ansari ◽  
Nir Y. Krakauer
Keyword(s):  
Climate Change ◽  
Drought Index ◽  
Risk Index ◽  
Trend Test ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Long Duration ◽  
Tree Edge ◽  
Edge Removal ◽  
The 1960S

In the wake of a rapidly changing climate, droughts have intensified, in both duration and severity, across the globe. The Germanwatch long-term Climate Risk Index ranks Pakistan among the top 10 countries most affected by the adverse effects of climate change. Within Pakistan, the province of Balochistan is among the most vulnerable regions due to recurring prolonged droughts, erratic precipitation patterns, and dependence on agriculture and livestock for survival. This study aims to explore how the characteristics of droughts have evolved in the region from 1902–2015 using 3-month and 12-month timescales of a popular drought index, the Standardized Precipitation Evapotranspiration Index (SPEI). The region was divided into six zones using Spatial “K”luster Analysis using Tree Edge Removal (SKATER) method, and run theory was applied to characterize droughts in terms of duration, severity, intensity, and peak. The results of the non-parametric Mann–Kendall trend test applied to SPEI indicate prevailing significant negative trends (dryer conditions) in all the zones. Balochistan experienced its most severe droughts in the 1960s and around 2000. The effects of climate change are also evident in the fact that all the long duration droughts occurred after 1960. Moreover, the number of droughts identified by 3-month SPEI showed a significant increase after 1960 for all six zones. The same trend was found in the 12-month SPEI but for only three zones.

scholarly journals Patterns and trends of high-impact weather in China during 1959–2014

2016 ◽  
Vol 16 (3) ◽  
pp. 855-869 ◽  
Author(s):  
Jun Shi ◽  
Kangmin Wen ◽  
Linli Cui
Keyword(s):  
Southern China ◽  
Eastern China ◽  
High Impact ◽  
Northeastern China ◽  
Central China ◽  
Western China ◽  
Tibet Plateau ◽  
High Mountain ◽  
Mitigation And Adaptation ◽  
High Impact Weather

Abstract. The spatial and temporal characteristics of the frequencies of four types of high-impact weather (HIW), i.e. snowfall, thunderstorms, fog and hailstorms, were analysed in China during 1959–2014. Results indicate a significant decrease in the number of snowfall days, thunderstorm days and thunderstorm spells in all six regions of China, with regional decreasing rates of 0.1–3.4 days, 1.6–5.1 days and 0.23–0.77 times per decade respectively. The number of foggy days, hailstorm days and snowfall spells decreased at rates of 0.2–1.8 days, 0.1–0.7 days and 0.14–0.44 times per decade respectively in almost all regions and fog and hailstorm spells decreased at rates of 0.06–0.17 and 0.001–0.043 times per decade respectively in most regions of China. Spatially, there was more snowfall in northeastern China and western China, and more thunderstorms in southern China and southwestern China. The number of fog events was larger in some high mountain stations, eastern China and central China. Hailstorms were concentrated on Qinghai–Tibet Plateau. Over the past 56 years, snowfall days, thunderstorm days and thunderstorm spells decreased in most parts of China, and hailstorm days decreased in northeastern China, most parts of northern China and Tibet, southern Qinghai and western Sichuan. The spatial trends of foggy days, foggy spells, snowfall spells and hailstorm spells were not significant in most parts of China. With global warming, some types of HIW are likely to increase in their intensities, so more mitigation and adaptation strategies are still essential for local government and the public in China.

scholarly journals Drought Trend Analysis Based on the Standardized Precipitation–Evapotranspiration Index Using NASA’s Earth Exchange Global Daily Downscaled Projections, High Spatial Resolution Coupled Model Intercomparison Project Phase 5 Projections, and Assessment of Potential Impacts on China’s Crop Yield in the 21st Century

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2455
Author(s):  
Xiaolin Guo ◽  
Yuan Yang ◽  
Zhansheng Li ◽  
Liangzhi You ◽  
Chao Zeng ◽  
...  
Keyword(s):  
Crop Yield ◽  
Spatial Resolution ◽  
Crop Production ◽  
Southern China ◽  
Extreme Drought ◽  
Severe Drought ◽  
High Latitudes ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Climate Data ◽  
The Impact

Drought is among the costliest natural disasters on both ecosystems and agroeconomics in China. However, most previous studies have used coarse resolution data or simply stopped short of investigating drought projection and its impact on crop yield. Motivated by the newly released higher-resolution climate projection dataset and the crucial need to assess the impact of climate change on agricultural production, the overarching goal of this study was to systematically and comprehensively predict future droughts at unprecedented resolutions over China as a whole. rather than region-specific projections, and then to further investigate its impact on crop yield by innovatively using a soil water deficit drought index. Methodologically, the drought projections were quantified from very high resolution climate data and further predicted impacts on crop yield over China using the standardized precipitation–evapotranspiration index (SPEI) at a relatively high (25 km) spatial resolution from NASA’s Earth Exchange Global Daily Downscaled Projections (NEX-GDDP). The results showed that (1) overall, China is projected to experience a significant decrease in SPEI (−0.15/decade under RCP (representative concentration pathway) 4.5; −0.14/decade under RCP8.5). Seasonally, the decreasing rate of SPEI is projected to be largest in winter (−0.2/decade and −0.31/decade) and the least in summer (−0.08/decade and −0.10/decade) under respective RCPs. (2) Regionally, winter/spring will get drier, especially at high latitudes/altitudes (North China and Tibetan plateau), and summer/autumn will get wetter in southern China. (3) Both the frequency and duration for medium and severe drought are projected to decrease, while extreme drought, particularly in high latitudes/altitudes, is projected to increase. (4) The percentage of the potential crop production affected by drought would increase to 36% (47%) by 2100 under RCP4.5 (RCP8.5). Especially, the ratio impacted by extreme drought is projected to increase over time and with much worse magnitude under RCP8.5; thus, adaptive crop policies are expected to address such a risk.

scholarly journals Long-term trends and spatiotemporal variations of climate comfort in China during 1966-2016

2020 ◽  
Vol 24 (4) ◽  
pp. 2445-2453
Author(s):  
Fei-Fei Wu ◽  
Xiao-Hua Yang ◽  
Zhen-Yao Shen ◽  
Ze-Ji Yi
Keyword(s):  
Southern China ◽  
Function Analysis ◽  
Well Being ◽  
Central China ◽  
Western China ◽  
Tibet Plateau ◽  
Seasonal Climate ◽  
Comfort Index ◽  
Sensitive Areas ◽  
Climate Comfort

Climate comfort and its variability are of great importance to human comfort, health and well-being, as humans may suffer dire consequences when they are exposed to the environments with heat or cold stress. The climate comfort index represented the integrated effects of meteorological variables on the human thermal sensation. The annual and seasonal climate comfort index values were calculated based on the monthly data of the temperature, relative humidity, and wind speed from 591 stations in China between 1966 and 2016. Using the empirical orthogonal function analysis, the dominant modes of climate comfort index variations were extracted by the first two modes, which accounted for more than 50% of the total variance. The results showed that the annual and seasonal climate comfort index values displayed a latitudinal gradient, and increased towards the south except for the Qinghai-Tibet Plateau. The most frequently perceived thermal sensations were labeled as ?cold?, ?comfortable?, ?cold? and ?extremely cold? conditions from spring to winter, respectively. For annual and seasonal climate comfort index, the consistent increasing trend was detected in most regions of China in the first mode. The sensitive areas were mainly located in the central, eastern and southern China in winter, while in the northern and western China in summer. In the second mode, the fluctuations between upward and downward trends were observed. The sensitive areas were located in the central China in summer, in the southwestern and southern China in autumn, and in the northern China in winter. This study provides the important information for the improvement of human settlement comfort.

scholarly journals Spatio-Temporal Variability of Drought in Pakistan Using Standardized Precipitation Evapotranspiration Index

2019 ◽  
Vol 9 (21) ◽  
pp. 4588 ◽  
Author(s):  
Shoaib Jamro ◽  
Ghulam Hussain Dars ◽  
Kamran Ansari ◽  
Nir Y. Krakauer
Keyword(s):  
Climate Change ◽  
Temporal Trends ◽  
Trend Test ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Northern Areas ◽  
Tree Edge ◽  
Edge Removal ◽  
History Of ◽  
Drying Trend ◽  
Spatio Temporal

Pakistan is among the top ten countries adversely affected by climate change. More specifically, there is concern that climate change may cause longer and severer spells of droughts. To quantify the change in the characteristics of droughts in Pakistan over the years, we have evaluated spatio-temporal trends of droughts in Pakistan over the period 1902–2015 using Standardized Precipitation Evapotranspiration Index (SPEI). Additionally, the Spatial “K” luster Analysis using Tree Edge Removal (SKATER) method was employed to regionalize droughts into five contiguous zones. The run theory was then applied to each zone to identify drought events and characterize them in terms of duration, severity, intensity, and peak. Moreover, the Modified Mann–Kendall trend test was applied to identify statistically significant trends in SPEI and drought characteristics in each zone. It was found that the southern areas of Pakistan, encompassing Sindh and most of Baluchistan, have experienced a decrease in SPEI, indicating a drying trend. Central Pakistan has witnessed a wetting trend as demonstrated by an increase in SPEI over time, whereas no statistically significant trend was observed for the northern areas of Pakistan. On a zonal basis, the longest duration drought to occur in Pakistan lasted 22 months in zone 5 (Sindh) from 1968 to 1970. In addition, the drought of 1920 and 2000 can be said to be the worst drought in the history of the region as it affected all the zones and lasted for more than 10-months in three zones.

scholarly journals Role of Suillus placidus in Improving the Drought Tolerance of Masson Pine (Pinus massoniana Lamb.) Seedlings

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 332
Author(s):  
Min Li ◽  
Haoyun Wang ◽  
Xizhou Zhao ◽  
Zhongke Lu ◽  
Xueguang Sun ◽  
...  
Keyword(s):  
Drought Stress ◽  
Defense Mechanism ◽  
Southern China ◽  
Dry Weight ◽  
Pinus Massoniana ◽  
Photosynthetic Performance ◽  
Ectomycorrhizal Fungus ◽  
Severe Drought ◽  
Masson Pine ◽  
Pine Seedlings

Masson pine is an important afforestation species in southern China, where seasonal drought is common. The present study focused on the effects of Suillus placidus, an ectomycorrhizal fungus, inoculation on the growth and physiological and biochemical performance of masson pine seedlings under four different watering treatments (well-watered, mild drought, moderate drought, and severe drought) to evaluate the symbiotic relationship between S. placidus and masson pine seedlings. Ectomycorrhizal-inoculated (ECM) and non-inoculated (NM) seedlings were grown in pots and maintained for 60 days using the weighing method. Results showed that seedlings’ growth, dry weight, RWC, chlorophyll content, PSII efficiency, and photosynthesis decreased as drought stress intensified in both ECM and NM plants. This suggests that drought stress significantly limits the growth and photosynthetic performance of masson pine seedlings. Nevertheless, increased An/gs and proline contents in both NM and ECM prevented oxidative damage caused by drought stress. In addition, increased peroxidase (POD) activity is an essential defense mechanism of ECM seedling under drought stress. Compared with NM, ECM seedlings showed faster growth, higher RWC, and photosynthetic performance, and lower lipid peroxidation in cell membranes under drought stress, as indicated by higher POD activity and lower proline and malondialdehyde (MDA). Our experiment found that S. placidus inoculation can enhance the drought resistance of masson pine seedlings by increasing antioxidant enzyme activity, water use efficiency, and proline content, thereby enhancing growth under water-deficiency conditions. S. placidus can be used to cultivate high-quality seedlings and improve their survival in regions that experience seasonal droughts.

Spatiotemporal pattern mining of drought in the last 40 years in China based on the SPEI index and space-time cube

2021 ◽  
Author(s):  
Dehe Xu ◽  
Qi Zhang ◽  
Yan Ding ◽  
De Zhang
Keyword(s):  
North China ◽  
Pattern Mining ◽  
Space Time ◽  
Central China ◽  
Spatiotemporal Pattern ◽  
Severe Drought ◽  
Monthly Precipitation ◽  
Hotspot Analysis ◽  
The Past ◽  
Significant Difference

AbstractDrought is a common natural disaster that greatly affects the crop yield and water supply in China. However, the spatiotemporal characteristics of drought in China are not well understood. This paper explores the spatial and temporal distributions of droughts in China over the past 40 years using multiscale standardized precipitation evapotranspiration index (SPEI) values calculated by monthly precipitation and temperature data from 612 meteorological stations in China from 1980 to 2019 and combines the space-time cube (STC), Mann-Kendall (M-K) test, emerging spatiotemporal hotspot analysis, spatiotemporal clustering and local outliers for the analysis. The results were as follows: 1) the drought frequency and STC show that there is a significant difference in the spatiotemporal distribution of drought in China, with the most severe drought in Northwest China, followed by the western part of Southwest China and the northern part of North China. 2) The emerging spatiotemporal hotspot analysis of SPEI6 over the past 40 years reveals two cold spots in subregion 4, indicating that future droughts in the region will be more severe. 3) A local outlier analysis of the multiscale SPEI yields a low-low outlier in western North China, indicating relatively more severe year-round drought in this area than in other areas. The low-high outlier in central China indicates that this region was not dry in the past and that drought will become more severe in this region in the future.

Observed and Projected Frontal Activities in East Asia

2021 ◽  
pp. 1-46
Author(s):  
Chia-Chi Wang ◽  
Huang-Hsiung Hsu ◽  
Ying-Ting Chen
Keyword(s):  
East Asia ◽  
Climate Model ◽  
Southern China ◽  
Model Performance ◽  
Moisture Flux ◽  
Central China ◽  
Cmip5 Models ◽  
The South ◽  
Front Detection ◽  
Local Moisture

AbstractAn objective front detection method is applied to ERA5, CMIP5 historical, and RCP8.5 simulations to evaluate climate model performance in simulating front frequency and understand future projections of seasonal front activities. The study area is East Asia for two natural seasons, defined as winter (December 2nd –February 14th) and spring (February 15th –May 15th), in accordance with regional circulation and precipitation patterns. Seasonal means of atmospheric circulation and thermal structures are analyzed to understand possible factors responsible for future front changes.The front location and frequency in CMIP5 historical simulations are captured reasonably. Frontal precipitation accounts for more than 30% of total precipitation over subtropical regions. Projections suggest that winter fronts will decrease over East Asia, especially over southern China. Frontal precipitation is projected to decrease for 10-30%. Front frequency increases in the South China Sea and tropical western Pacific because of more tropical moisture supply, which enhances local moisture contrasts. During spring, southern China and Taiwan will experience fewer fronts and less frontal precipitation while central China, Korea, and Japan may experience more fronts and more frontal precipitation due to moisture flux from the south that enhances 𝜽𝒘 gradients.Consensus among CMIP5 models in front frequency tendency is evaluated. The models exhibit relatively high consensus in the decreasing trend over polar and subtropical frontal zone in winter and over southern China and Taiwan in spring that may prolong the dry season. Spring front activities are crucial for water resource and risk management in the southern China and Taiwan.

scholarly journals Genome-Wide Analysis Reveals Genetic Structure and Selective Sweeps in Chinese Indigenous Pig Breeds

2019 ◽  
Author(s):  
Xiong Tong ◽  
Lianjie Hou ◽  
Weiming He ◽  
Chugang Mei ◽  
Bo Huang ◽  
...  
Keyword(s):  
Yangtze River ◽  
North China ◽  
Phenotypic Diversity ◽  
Southern China ◽  
Linkage Disequilibrium Block ◽  
Genetic Material ◽  
Morphological Characteristics ◽  
Central China ◽  
Pig Breeds ◽  
Southern Chinese

Abstract Background Chinese indigenous pigs exhibit considerable phenotypic diversity, but their population structure and the genetic basis of agriculturally important traits have not been explored. Results Here, we sequenced the whole genomes of 24 individual pigs representing 22 breeds distributed throughout China. For comparison with European and commercial breeds (one pig per breed), we integrated seven published pig genomes with our new genomes. Our results showed that pig domestication occurred at three places in Southeastern Asia, namely the Mekong region, the middle to downstream regions of the Yangtze River, and Tibetan highlands. Moreover, we demonstrated that classic morphological characteristics such as coat color are not consistent with genetic data. We found that genetic material from European pigs likely introgressed into five Chinese breeds. Two new subpopulations of domestic pigs have been identified in South and North China that encompass morphology-based criteria. The Southern Chinese subpopulation comprises the classical Southern China Type and part of the Central China Type, whereas the Northern Chinese subpopulation comprises the North China Type, the Lower Yangtze River Basin Type, the Southwest Type, the Plateau Type, and the remainder of the Central China Type. Eight haplotypes and two recombination sites were identified within a conserved 40.09 Mb linkage-disequilibrium block on the X chromosome. Potential selection and domestication signatures were identified, mainly influencing body size, along with adaptations to cold and hot temperature environments. Conclusions Our findings provide insights into the phylogeny of Chinese indigenous pig breeds, and will be of enormous benefit in identifying beneficial genes to develop superior pig breeds.

scholarly journals Heatwave Trends and the Population Exposure Over China in the 21st Century as Well as Under 1.5 °C and 2.0 °C Global Warmer Future Scenarios

2019 ◽  
Vol 11 (12) ◽  
pp. 3318 ◽  
Author(s):  
Zhansheng Li ◽  
Xiaolin Guo ◽  
Yuan Yang ◽  
Yang Hong ◽  
Zhongjing Wang ◽  
...  
Keyword(s):  
Global Warming ◽  
21St Century ◽  
Climate Adaptation ◽  
Southern China ◽  
Total Duration ◽  
Central China ◽  
Population Exposure ◽  
The Tibetan Plateau ◽  
Time Frequency ◽  
Annual Total

Heatwaves exert negative socio-economic impacts and particularly have serious effects on public health. Based on the multi-model ensemble (MME) results of 10 downscaled high-resolution Fifth Phase of the Coupled Model Intercomparison Project (CMIP5) model output from NASA Earth Exchange Global Daily Downscaled Projections (NASA-GDDP), the intensity (largest lasting time), frequency and total duration of heatwaves over China as well as population exposure in the 21st century and at 1.5 °C and 2.0 °C above pre-industrial levels are investigated by using the three indices, the Heat Wave Duration Index (HWDI), annual total frequency of heatwaves (N_HW) and annual total days of heatwaves (T_HW) under RCP4.5 and RCP8.5. The MME results illustrate that heatwaves are projected to become more frequent (0.40/decade and 1.26/decade for N_HW), longer-lasting (3.78 days/decade and 14.59 days/decade for T_HW) as well as more extreme (1.07 days/decade and 2.90 days/decade for HWDI under RCP4.5 and RCP8.5 respectively) over China. High latitude and high altitude regions, e.g., the Tibetan Plateau and northern China, are projected to experience a larger increase of intensity, frequency and the total time of heatwaves compared with southern China (except Central China). The total population affected by heatwaves is projected to increase significantly and will reach 1.18 billion in later part of the 21st century, and there will be more and more people expected to suffer long heatwave time (T_HW) in the 21st century. Compared with a 2.0 °C global warming climate, holding the global warming below 1.5 °C can avoid 26.9% and 29.1% of the increase of HWDI, 34.7% and 39.64% for N_TW and 35.3%–40.10% of T_HW under RCP4.5 and RCP8.5 respectively. The half-degree less of warming will not only decrease the population exposure by 53–83 million but also avoid the threat caused by longer heatwave exposure under the two scenarios. Based on the comprehensive assessment of heatwave under the two RCP scenarios, this work would help to enhance the understanding of climate change and consequent risk in China and thus could provide useful information for making climate adaptation policies.

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