高文兰, 李双双, 段克勤, 孔锋, 王娟.
[Gao Wenlan, Li Shuangshuang, Duan Keqin, Kong Feng, Wang Juan.
Changes of Extreme Temperature Events in Xi’an City Based on Homogenized Data[J].
Scientia Geographica Sinica,
National Natural Science Foundation of China (41701592, 41571062), Fundamental Research Funds for the Central Universities (GK201703048).;
Changes of Extreme Temperature Events in Xi’an City Based on Homogenized Data
Gao Wenlan1,2,, Li Shuangshuang1,2,, Duan Keqin1,2, Kong Feng3, Wang Juan4
1. School of Geography and Tourism, Shaanxi Normal University, Xi’an 710119, Shaanxi, China;2. National Demonstration Center for Experimental Geography Education(Shaanxi Normal University), Xi’an 710119, Shaanxi, China;3. Research Centre for Strategic Development, China Meteorological Administration, Beijing 100081, China4. Shaanxi Meteorological Administration, Xi’an 710119, Shaanxi, China;
Based on daily maximum and minimum temperatures observed by the China Meteorological Administration at the Xi’an meteorological station during the period 1960-2015, the series exhibiting breakpoints are adjusted using RH test software. Temporal trends of 16 extreme temperature indices are evaluated by least-squares linear regression and moving average methods; the linear trends are significant for 11 of these 16 indices. The trends of extreme temperature indices for Xi’an, China, the globe, and other regions in China are compared. Further, trends of the relative magnitudes of cold versus warm indices and day versus night indices are compared. The results are as follows: 1) Due to the migration of the meteorological station, the value of the temperature series is lower than the original meteorological station data. The warming trends of extreme temperatures are underestimated based on the in-homogeneity dataset. 2) In the context of global warming, extreme temperature variation presents its own characteristics in Xi’an. First, the extreme temperature trends show rapid warming with stable fluctuation, but the opposite trends occur in warm and cold indices; warm indices increase while cold indices decrease. Second, the warming trends are faster during the nighttime than the daytime, whereas the amplitudes of fluctuations are greater during the daytime than the nighttime. Third, warm spell events increase slowly, but cold spell events decrease rapidly. 3) Extreme temperature indices are compared between Xi’an and other regions (the southern and northern regions of the Qinling Mountains, the Loess Plateau, northeast China, etc.). Due to the impact of the urban heat island phenomenon, the decrease of extreme low temperature events is more pronounced in Xi’an than in the other regions compared. 4) With regard to daytime versus nighttime indices, the nighttime indices in all regions show the characteristic of warming faster than the daytime indices. In the case of cold versus warm indices, Xi’an exhibits its regional features: the warming magnitude is faster on cold days than on warm days, and a similar trend is seen on cold nights and warm nights; indices of cold and warm spell durations show a downward trend. Overall, this study indicates that the trends of temperature extremes in Xi’an are in accordance with global warming during 1960-2015.
Alexander LV, ZhangX, Peterson T C et al. Global observed changes in daily climate extremes of temperature and precipitation[J]. , 2006, 111(D5):1042-1063.
A suite of climate change indices derived from daily temperature and precipitation data, with a primary focus on extreme events, were computed and analyzed. By setting an exact formula for each index and using specially designed software, analyses done in different countries have been combined seamlessly. This has enabled the presentation of the most up-to-date and comprehensive global picture of trends in extreme temperature and precipitation indices using results from a number of workshops held in data-sparse regions and high-quality station data supplied by numerous scientists world wide. Seasonal and annual indices for the period 1951-2003 were gridded. Trends in the gridded fields were computed and tested for statistical significance. Results showed widespread significant changes in temperature extremes associated with warming, especially for those indices derived from daily minimum temperature. Over 70% of the global land area sampled showed a significant decrease in the annual occurrence of cold nights and a significant increase in the annual occurrence of warm nights. Some regions experienced a more than doubling of these indices. This implies a positive shift in the distribution of daily minimum temperature throughout the globe. Daily maximum temperature indices showed similar changes but with smaller magnitudes. Precipitation changes showed a widespread and significant increase, but the changes are much less spatially coherent compared with temperature change. Probability distributions of indices derived from approximately 200 temperature and 600 precipitation stations, with near-complete data for 1901-2003 and covering a very large region of the Northern Hemisphere midlatitudes (and parts of Australia for precipitation) were analyzed for the periods 1901-1950, 1951-1978 and 1979-2003. Results indicate a significant warming throughout the 20th century. Differences in temperature indices distributions are particularly pronounced between the most recent two periods and for those indices related to minimum temperature. An analysis of those indices for which seasonal time series are available shows that these changes occur for all seasons although they are generally least pronounced for September to November. Precipitation indices show a tendency toward wetter conditions throughout the 20th century.
Klein A MG, Konnen GP. Trends in indices of daily temperature and precipitation extremes in Europe, 1946-99[J]. , 2003, 16(22):3665-3680.
Trends in indices of climate extremes are studied on the basis of daily series of temperature and precipitation observations from more than 100 meteorological stations in Europe. The period is 194609“99, a warming episode. Averaged over all stations, the indices of temperature extremes indicate 0904symmetric0909 warming of the cold and warm tails of the distributions of daily minimum and maximum temperature in this period. However, 0904asymmetry0909 is found for the trends if the period is split into two subperiods. For the 194609“75 subperiod, an episode of slight cooling, the annual number of warm extremes decreases, but the annual number of cold extremes does not increase. This implies a reduction in temperature variability. For the 197609“99 subperiod, an episode of pronounced warming, the annual number of warm extremes increases 2 times faster than expected from the corresponding decrease in the number of cold extremes. This implies an increase in temperature variability, which is mainly due to stagnation in the warming of the cold extremes. For precipitation, all Europe-average indices of wet extremes increase in the 194609“99 period, although the spatial coherence of the trends is low. At stations where the annual amount increases, the index that represents the fraction of the annual amount due to very wet days gives a signal of disproportionate large changes in the extremes. At stations with a decreasing annual amount, there is no such amplified response of the extremes. The indices of temperature and precipitation extremes in this study were selected from the list of climate change indices recommended by the World Meteorological Organization09“Commission for Climatology (WMO09“CCL) and the Research Programme on Climate Variability and Predictability (CLIVAR). The selected indices are expressions of events with return periods of 509“60 days. This means that the annual number of events is sufficiently large to allow for meaningful trend analysis in 09030450 yr time series. Although the selected indices refer to events that may be called 0904soft0909 climate extremes, these indices have clear impact relevance.
Peterson TC, Manton MJ.Monitoring changes in climate extremes: A tale of international collaboration[J]. , 2008, 89(9):1266-1271.
Abstract The monitoring and analysis of daily climate records to identify trends in extreme climate events have been primarily limited to data from Canada, the US, the Soviet Union, China, and Australia. Their data was hard to analyze since they used varying measures of extremes. As such, the need to update and converge the findings has been recognized at the November 1999 meeting of what is now known as the joint Expert Team on Climate Change Detection and Indices. The task was to converge the exact formulation of a suite of agreed indices of climate extremes from daily data and the organization of a regional climate-change workshops. As of 2004, a total of five workshops have been conducted in Melbourne. The workshops included participants from neighboring countries and from other areas of the world to provide guidance on the analysis of the climate data.
Chambers LE, Griffiths GM.The changing nature of temperature extremes in Australia and New Zealand[J]. , 2007, 57(57):13-35.
ABSTRACT A dense network of stations in Australia and New Zealand, including urbanised sites, was analysed to assess urbanisation effects on indices of extreme temperature, type of distribution change observed, and relationships with key climate drivers (El Ni o Southern Oscillation (ENSO), sea-surface temperature (SST) and mean sea-level pressure (MSLP) patterns). A strong spatial and temporal coherence of trends in extreme temperature indices was notable across both rural and urban stations, except for diurnal temperature range which was strongly influenced by urbanisation and biased by data limitations. Increased mean maximum and mean minimum temperature, general increases in hot days and warm nights, and decreases in cool days and cold nights, persisted over three analysis periods (1931-2005, 1946-2005 and 1961-2005), with the proportion of significant trends increasing as analysis period lengthened for all indices except hot days. Rural stations had fewer significant increasing trends in warm extremes, while urbanised sites showed a greater number of significant hot day increases. Strong correlations were found between measures of mean temperature and temperature extremes, consistent across all three analysis periods and largely independent of urban status. The most common form of distributional change, for both maximum and minimum temperature, involved a significant shift in the mean and one or both extremes. However, the proportion of stations with this type of distribution shift reduced in the later period, with relatively more stations having no distribution change, or shifts in the mean (but not extremes) over 1961-2005, possibly due to a change in the relationship between ENSO and temperature and/or the effects of rapid population growth since the 1950s. This study indicates that measures of ENSO, such as NINO3.4 or our second MSLP pattern, have the potential to better predict temperature extremes over large areas of Australasia, especially eastern Australia, compared to other broadscale climate indices, such as near-global SST patterns.
Sun WY, Mu XM, Song X Y et al. Changes in extreme temperature and precipitation events in the Loess Plateau (China) during 1960-2013 under global warming[J]. , 2016, 168(22):33-48.
In recent decades, extreme climatic events have been a major issue worldwide. Regional assessments on various climates and geographic regions are needed for understanding uncertainties in extreme events' responses to global warming. The objective of this study was to assess the annual and decadal trends in 12 extreme temperature and 10 extreme precipitation indices in terms of intensity, frequency, and duration over the Loess Plateau during 1960–2013. The results indicated that the regionally averaged trends in temperature extremes were consistent with global warming. The occurrence of warm extremes, including summer days (SU), tropical nights (TR), warm days (TX90), and nights (TN90) and a warm spell duration indicator (WSDI), increased by 2.76 ( P 02<020.01), 1.24 ( P 02<020.01), 2.60 ( P 02=020.0003), 3.41 ( P 02<020.01), and 0.68 ( P 02=020.0041) days/decade during the period of 1960–2013, particularly, sharp increases in these indices occurred in 1985–2000. Over the same period, the occurrence of cold extremes, including frost days (FD), ice days (ID), cold days (TX10) and nights (TN10), and a cold spell duration indicator (CSDI) exhibited decreases of 61023.22 ( P 02<020.01), 61022.21 ( P 02=020.0028), 61022.71 ( P 02=020.0028), 61024.31 ( P 02<020.01), and 61020.69 ( P 02=020.0951) days/decade, respectively. Moreover, extreme warm events in most regions tended to increase while cold indices tended to decrease in the Loess Plateau, but the trend magnitudes of cold extremes were greater than those of warm extremes. The growing season (GSL) in the Loess Plateau was lengthened at a rate of 3.1602days/decade ( P 02<020.01). Diurnal temperature range (DTR) declined at a rate of 61020.0602°C /decade ( P 02=020.0931). Regarding the precipitation indices, the annual total precipitation (PRCPTOT) showed no obvious trends ( P 02=020.7828). The regionally averaged daily rainfall intensity (SDII) exhibited significant decreases (61020.1402mm/day/decade, P 02=020.0158), whereas consecutive dry days (CDD) significantly increased (1.9602days/decade, P 02=020.0001) during 1960–2013. Most of stations with significant changes in SDII and CDD occurred in central and southeastern Loess Plateau. However, the changes in days of erosive rainfall, heavy rain, rainstorm, maximum 5-day precipitation, and very-wet-day and extremely wet-day precipitation were not significant. Large-scale atmospheric circulation indices, such as the Western Pacific Subtropical High Intensity Index (WPSHII) and Arctic Oscillation (AO), strongly influences warm/cold extremes and contributes significantly to climate changes in the Loess Plateau. The enhanced geopotential height over the Eurasian continent and increase in water vapor divergence in the rainy season have contributed to the changes of the rapid warming and consecutive drying in the Loess Plateau.
Guan YH, Zhang XC, Zheng F L et al. Trends and variability of daily temperature extremes during 1960-2012 in the Yangtze River Basin, China[J]. , 2015, 124:79-94.
The variability of surface air temperature extremes has been the focus of attention during the past several decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Based on daily minimum (TN) and maximum temperature (TX) observed by the China Meteorological Administration at 143 meteorological stations in the Yangtze River Basin (YRB), a suite of temperature indices recommended by the Expert Team on Climate Change Detection and Indices, with a primary focus on extreme events, were computed and analyzed for the period of 1960–2012 for this area. The results show widespread significant changes in all temperature indices associated with warming in the YRB during 1960–2012. On the whole, cold-related indices, i.e., cold nights, cold days, frost days, icing days and cold spell duration index significantly decreased by 61023.45, 61021.03, 61023.04, 61020.42 and 61021.602days/decade, respectively. In contrast, warm-related indices such as warm nights, warm days, summer days, tropical nights and warm spell duration index significantly increased by 2.95, 1.71, 2.16, 1.05 and 0.7302days/decade. Minimum TN, maximum TN, minimum TX and maximum TX increased significantly by 0.42, 0.18, 0.19 and 0.1402°C/decade. Because of a faster increase in minimum temperature than maximum temperature, the diurnal temperature range (DTR) exhibited a significant decreasing trend of 61020.0902°C/decade for the whole YRB during 1960–2012. However, the decreasing trends all occurred in 1960–1985, while increasing trends though insignificant were found in all sub-regions and the whole YRB during 1986–2012. Geographically, stations in the eastern Tibet Plateau and northeastern YRB showed stronger trends in almost all temperature indices. Time series analysis indicated that the YRB was dominated by a general cooling trend before the mid-1980s, but a warming trend afterwards. In general, the overall warming in the YRB was mainly due to the warming in 1986–2012. Strong relationships between temperature trends and elevation were detected in this study. The warming rates increased with elevation when elevation is above 35002m, but decreased with elevation when elevation is below 35002m.
[HuangXiaoyan, WangXiaoping, WangJinsong et al. Variation of extreme temperature events in coastal region of China in 1960-2013. ,2016,36(4):612-620.]
You QL, Kang SC, AguilarE et al. Changes in daily climate extremes in China and their connection to the large scale atmospheric circulation during 1961-2003[J]. , 2011, 36(11):2399-2417.
Based on daily maximum and minimum surface air temperature and precipitation records at 303 meteorological stations in China, the spatial and temporal distributions of indices of climate extremes are analyzed during 1961–2003. Twelve indices of extreme temperature and six of extreme precipitation are studied. Temperature extremes have high correlations with the annual mean temperature, which shows a significant warming of 0.27°C/decade, indicating that changes in temperature extremes reflect the consistent warming. Stations in northeastern, northern, northwestern China have larger trend magnitudes, which are accordance with the more rapid mean warming in these regions. Countrywide, the mean trends for cold days and cold nights have decreased by 610.47 and 612.0602days/decade respectively, and warm days and warm nights have increased by 0.62 and 1.7502days/decade, respectively. Over the same period, the number of frost days shows a statistically significant decreasing trend of 613.3702days/decade. The length of the growing season and the number of summer days exhibit significant increasing trends at rates of 3.04 and 1.1802days/decade, respectively. The diurnal temperature range has decreased by 610.18°C/decade. Both the annual extreme lowest and highest temperatures exhibit significant warming trends, the former warming faster than the latter. For precipitation indices, regional annual total precipitation shows an increasing trend and most other precipitation indices are strongly correlated with annual total precipitation. Average wet day precipitation, maximum 1-day and 5-day precipitation, and heavy precipitation days show increasing trends, but only the last is statistically significant. A decreasing trend is found for consecutive dry days. For all precipitation indices, stations in the Yangtze River basin, southeastern and northwestern China have the largest positive trend magnitudes, while stations in the Yellow River basin and in northern China have the largest negative magnitudes. This is inconsistent with changes of water vapor flux calculated from NCEP/NCAR reanalysis. Large scale atmospheric circulation changes derived from NCEP/NCAR reanalysis grids show that a strengthening anticyclonic circulation, increasing geopotential height and rapid warming over the Eurasian continent have contributed to the changes in climate extremes in China.
[SunXian, WeiNa, HaoLi et al. Characteristics of extreme temperature events in Xi’an for the latest 60 years. , 2014, 44(6):997-1000.]
YuZ, Li X L. Recent trends in daily temperature extremes over northeastern China (1960-2011)[J]. , 2015, 380-81:35-48.
Based on long-term, high-quality, and homogenous daily maximum and minimum temperature of 70 meteorological stations spanning the period from 1960 to 2011, the spatial and temporal characteristics of extreme temperature events in northeastern China have been investigated. A total of 14 indices are used to assess changes in extreme temperature distributions. All the temperature-based indices show patterns consistent with a general warming trend. The regional occurrence of the increase in warm nights (TN90p: 2.1702days/decade) and warm days (TX90p: 0.9702days/decade), and decrease in cool nights (TN10p:02611.8002days/decade) and cool days (TXx:02610.8602days/decade) was detected in the past 52 years. Moreover, the trend magnitudes in cold/warm nights are larger than those in cold/warm days, which indicate that trends in minimum temperature extremes are more rapid than trends in maximum temperature extremes, consistent with a long-term decrease in DTR. The other indices, including TNn, TNx, SU25, TR20, FD0, ID0, GSL, and DTR, show statistically significant changes except for Maximum and minimum values of maximum daily temperatures (TXx and TXn) which have statistically insignificant slopes at individual stations and in regional mean trend. For the majority of stations, significant increases are detected for heat related extremes such as summer days and tropical nights (SU25 and TR20) as well as for maximum and minimum values of minimum daily temperatures (TNn and TNx); With the exception of diurnal temperature range (DTR) and maximum daily maximum temperature (TXx), the other indices strongly correlate with annual mean temperature. In addition, there are high correlations among warm indices and among cold ones, respectively.
JiangC, Mu XM, WangF et al. Analysis of extreme temperature events in the Qinling Mountains and surrounding area during 1960-2012[J]. , 2016, 392(4):155-167.
In this study, 16 indices of extreme temperature were calculated on the basis of daily maximum and minimum temperature data in the northern and southern regions of the Qinling Mountains (NSQ) using linear trend and correlation analysis and other methods to investigate the temporal variation trend, spatial distribution pattern and correlation of extreme temperature events. The results are as follows. (1) The extreme cold and warm indices exhibited contrasting variation trends over the entire region: the cold indices (TX10, TN10, ID, FD and CSDI) decreased; the warm indices (TX90, TN90, SU, TR and WSDI) increased; the extremal indices (TXn, TNn, TXx and TXn) increased; and the diurnal temperature range (DTR) decreased. (2) The absolute indices, extremal indices and other indices showed a certain latitudinal zonality: ice days (ID) and frost days (FD) decreased from north to south, while summer days (SU), tropical nights (TR), extremal indices (TXn, TNn, TXx and TXn), the cold and warm spell duration indicators (CSDI and WSDI, respectively) and growing season length (GSL) increased from north to south. (3) The correlation analysis results showed that, except for the extremal indices and individual indices, the extreme temperature indices correlated well. (4) The altitude has a large impact on spatial distribution of extreme temperature indices, and the ubiquity of the heat island effect in urban constructed regions also had an impact on amplitude of variation in extreme temperature.
Zhou BT, XuY, WuJ et al. Changes in temperature and precipitation extreme indices over China: analysis of a high-resolution grid dataset[J]. , 2015, 36(3):1051-1066.
ABSTRACT Based on the high-resolution gridding data (CN05) from 2416 station observations, a grid dataset of temperature and precipitation extreme indices with the resolution of 0.5°65×650.5° for China region was developed using the approach recommended by the Expert Team on Climate Change Detection and Indices. This article comprehensively presents temporal and spatial changes of these indices for the time period 1961–2010. Results showed widespread significant changes in temperature extremes consistent with warming, for instance, decreases in cold extremes and increases in warm extremes over China. The warming in the coldest day and night is larger than the warmest day and night, respectively, which is concurrent with the coldest night larger than the coldest day and the warmest night larger than the warmest day. Changes in the number of the cold and warm nights are more remarkable than the cold and warm days. Changes in precipitation extremes are, in general, spatially more complex and exhibit a less widespread spatial coverage than the temperature indices, for instance, the patterns of annual total precipitation amount, average daily precipitation rate, and the proportion of heavy precipitation in total annual precipitation are similar with negative trends in a southwest–northeast belt from Southwest China to Northeast China while positive trends in eastern China and northwestern China. The consistency of changes in climate extremes from the CN05 with other datasets based on the stations and reanalyses is also analysed.
Donat MG, Alexander LV, YangH et al. Global land-based datasets for monitoring climatic extremes[J]. , 2013, 94(7):997-1006.
The World Meteorological Organization (WMO) Commission for Climatology (CCl)/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI) held a number of regional workshops whose data were used to help create HadEX, the first global land-based, gridded dataset of temperature and precipitation extremes. Experts from ETCCDI developed a new dataset to address the issues of HadEX, using the world's largest repository of daily in situ observations of temperature and precipitation. The resulting dataset was known as GHCNDEX, which was an operationally updated, global land gridded dataset of climate extremes. The experts also demonstrated the application of the dataset for climate change and climate monitoring purposes in addition to assessing some issues regarding uncertainty by comparing the results with existing datasets.