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In China and East Asia, the long-term continuous observational data at daily resolution are insufficient, and thus there is a lack of good understanding of the extreme climate variation over the last 100 years plus. In this study, the extreme temperature indices defined by ETCCDI (Expert Team on Climate Change Detection and Indices) and local meteorological administrations were analyzed for Changchun City, Northeast China, by using the daily maximum temperature (Tmax) and daily minimum temperature (Tmin) over 1909–2018. The results showed that extreme cold events, such as cold days, cold nights, frost days, icing days, and low temperature days, decreased significantly at rates of −0.41 d (10 yr)−1, −1.45 d (10 yr)−1, −2.28 d (10 yr)−1, −1.16 d (10 yr)−1 and −1.90 d (10 yr)−1, respectively. Warm nights increased significantly at a rate of 1.71 d (10 yr)−1, but warm days decreased slightly and the number of high temperature days decreased at a rate of −0.20 d (10 yr)−1. The frequency of cold surge events increased significantly at a rate of 0.25 d (10 yr)−1, occurring mainly from the mid-1950s to late-1980s. The average Tmax, average Tmin and extreme Tmin increased at rates of 0.09°C (10 yr)−1, 0.36°C (10 yr)−1 and 0.54°C (10 yr)−1, respectively; and extreme Tmax decreased significantly at a rate of −0.17°C (10 yr)−1. In 1909−2018, 1951−2018 and 1979−2018, the indices related to cold events decreased, while the trends of the indices related to warm events were different for different periods. [ABSTRACT FROM AUTHOR]

Instrumental data from the pre–Industrial Revolution period are important to -understand climate change. In this paper, the observations made by the French missionary J. Amiot in present-day central Beijing during 1757–62 were processed and analyzed. The observations represent the earliest continuous dataset of meteorological records found in China that have been digitized recently. Comparisons between the Amiot annual temperature range and extreme values with modern observations showed that the observations were read at approximately 0800 and 1500 local solar time (LST) in a well-ventilated outdoor site. The daily maximum, minimum, and mean temperatures (T-max, T-min, and T-mean, respectively) during 1757–62 were determined by examining the relationship between temperature at 0800 and 1500 LST and T-max, T-min, and T-mean in modern reference series. Nearly 260 years ago, Beijing's climate was typical of an inland temperate monsoon zone with annual T-mean, annual mean T-max, and annual mean T-min being 11.5°, 17.8°, and 6.1°C, respectively; further, the temperatures did not vary considerably from the 1951–1980 temperatures, but differed evidently compared to relatively recent decades (1981–2020). The difference was larger than the magnitudes of global and regional temperature changes. Thus, climate warming since the pre–Industrial Revolution period in the urban areas of Beijing has dominantly occurred over the last four decades. Uncertainties related to the thermometer and observational conditions 260 years ago and the interpolation method used have also been discussed in this paper. [ABSTRACT FROM AUTHOR]

The understanding of centennial trends of extreme temperature has been impeded due to the lack of early-year observations. In this paper, we collect and digitize the daily temperature data set of Northeast China Yingkou meteorological station since 1904. After quality control and homogenization, we analyze the changes of mean and extreme temperature in the past 114 years. The results show that mean temperature (Tmean), maximum temperature (Tmax), and minimum temperature (Tmin) all have increasing trends during 1904–2017. The increase of Tmin is the most obvious with the rate of 0.34 °C/decade. The most significant warming occurs in spring and winter with the rate of Tmean reaching 0.32 °C/decade and 0.31 °C/decade, respectively. Most of the extreme temperature indices as defined using absolute and relative thresholds of Tmax and Tmin also show significant changes, with cold events witnessing a more significant downward trend. The change is similar to that reported for global land and China for the past six decades. It is also found that the extreme highest temperature (1958) and lowest temperature (1920) records all occurred in the first half of the whole period, and the change of extreme temperature indices before 1950 is different from that of the recent decades, in particular for diurnal temperature range (DTR), which shows an opposite trend in the two time periods. [ABSTRACT FROM AUTHOR]

Previous observational analyses show that the land-surface diurnal temperature range (DTR) has decreased in the past 6 decades worldwide. Based on a newly developed China Meteorological Administration-Land Surface Air Temperature (CMA-LSAT) dataset, we analyzed the DTR changes between 1901 and 2014. Results indicate that the global land surface DTR significantly decreased at a rate of − 0.036 °C decade− 1 over the 1901-2014 period, mainly due to the large decrease in DTR from 1951 to 2014. For the first half of the twentieth century, most grid boxes (spatial resolution 5° × 5°) show a positive DTR trend, with the positive trends of 32.4% grid boxes being statistically significant, leading to a large and significant increase of 0.048 °C decade− 1 in DTR. However, a dramatic reversal in DTR change occurred in early 1950s, with most parts of global lands exhibiting a shift from increasing to decreasing trends. The global land average DTR decrease during 1951-2014 was − 0.054 °C decade− 1, with 45.0% grid boxes showing significant negative trends. The reverse phenomenon is more obvious in the Northern Hemisphere than that in the Southern Hemisphere. For the periods 1979-2014 and 1998-2014, the decreasing trends in DTR mainly occur in the Northern Hemisphere. The DTR in the Southern Hemisphere experienced much larger increases during the two recent periods than during the period 1951-2014. Asia, Eastern North America, and Australia exhibited widespread decreases in DTR, although the trend pattern for global DTR is generally mixed during 1979-2014 and 1998-2014. There is a good negative correlation between DTR and precipitation in the Northern Hemisphere from 1901 to 2014, with a correlation coefficient of − 0.61. The change in precipitation and number of volcanic eruptions, and the "early brightening" of Europe (Stockholm) all benefit the increase of DTR at global and regional scales in the first half of the twentieth century. [ABSTRACT FROM AUTHOR]