Season In China Research Articles

An estimation of CO2 emission via agricultural crop residue open field burning in China from 1996 to 2013

The field burning of agriculture straw residue is a common method to dispose waste after harvesting seasons in China. The burning of agricultural crop residue in open field which has been given little attention up till now represents an important source of CO2 for global warming concern. According to the CO2 emission factors of rice, wheat, and corn straws based on laboratory measurements, the amount of CO2 emission via agricultural crop residue open burning in China between 1996 and 2013 has been calculated. The diverse accounting methods and geographic information system (GIS) are used to map the CO2 emission of thirty-one provinces. Identifying the spatial distribution, 5-year average variation, and contributions of CO2 emission by three major agricultural residue open burning, it is found: (i) About 2707.34 Tg of CO2 is emitted by agriculture residue open burning, occupies 45.09% of the total residential coal consumption from 1996 to 2013 (ii) The total emission from rice, wheat and corn straw burning are concentrated in south and northeast of China, North China and northeast of China, respectively (iii) Shandong Province contributes the largest portion of CO2 emission, Henan, Jiangsu, Hebei and Hei Longjiang rank the second, third, forth, and fifth, respectively. From different level of CO2 emission by agricultural crop residue open burning, we can find mitigation potential of greenhouse gas emission and give three suggestions: (i) generalizing straw returning field application (ii) improving the efficiency of straw utilization (iii) commercializing biomass energy. However, the mitigation potential, and varied policies and regulations need to be developed which are related to the local economic and environmental conditions in different China rural places.

Aerosol Optical and Microphysical Properties of Four Typical Sites of SONET in China Based on Remote Sensing Measurements

The current understanding of columnar aerosol optical and microphysical properties of different regions and seasons in China is insufficient due to the lack of measurements. Aiming to improve descriptions of aerosol models over China, this paper presents a systematic aerosol characterization of different sites based on a newly developed remote sensing network for aerosol observation, the Sun-sky radiometer Observation NETwork (SONET). One year of ground-based solar and sky radiation measurements of four typical sites of SONET (Beijing–urban-industrial site, Zhangye—rural site, Minqin—desert site, Zhoushan–oceanic site) are used to retrieve aerosol properties using similar inversion algorithms with AErosol RObotic NETwork (AERONET), including aerosol optical depth, Ångström exponent, volume size distribution, complex refractive index, single scattering albedo, and percentage of spherical particles. The retrieved properties among sites and seasons are found to be different in terms of magnitude, spectral dependence, and partition of fine and coarse mode, which can be primarily explained by different aerosol composition and mixing states that closely relate to the local climate, the natural environment, and most importantly, the ubiquitous anthropogenic impacts. For example, large dust particles greatly contribute to the low fine mode fraction in both volume concentration and optical depth for the Minqin site through the entire year, while abundant small particles that mainly come from emission sources dominate the size distribution and light extinction of aerosol in the summer at the Beijing site. The results also show general agreements with other studies on the aerosol properties at each site, however, some unique features are still noticeable, especially at the desert site and oceanic site (e.g., the unusually strong aerosol absorptivity indicated by the large imaginary refractive index and low single scattering albedo at the Minqin and Zhoushan sites), which can be partly attributed to the existence of absorbing particles coming from anthropogenic sources.

Carbon dioxide enrichment and brassinosteroid pretreatment alleviate chlorpyrifos phytotoxicity under suboptimal light and temperature conditions in tomato

Phytotoxicity is a daunting challenge for facility agriculture, and a crop is more susceptible to phytotoxicity under sub-optimum growth conditions. Although the practical values of brassinosteroid (BR) treatment or CO2 enrichment in promoting crop yield have been confirmed, few studies have focused on the regulation of pesticide phytotoxicity, especially under sub-optimum growth conditions. In this study, the phytotoxicity of chlorpyrifos was evaluated mainly by monitoring the transcriptional responses of genes involved in various physiological processes in tomato leaves under chilling temperature and low light, which occur frequently during the cool season in China. Additionally, we investigated whether 24-epibrassinolide (EBR) pretreatment (0.1μmol/L) or CO2 enrichment (1000μmol/mol) could mitigate this phytotoxicity. The treatment of chlorpyrifos decreased the transcriptions of photosynthetic and defense genes and increased those of antioxidant and detoxification genes. EBR pretreatment significantly increased the transcription of antioxidant, detoxification and defense genes, which could enhance the tolerance of the plants to pesticides and mitigate the phytotoxicity, as indicated by the increased mRNA level for photosynthetic genes. Similar observations were found with CO2 enrichment, and the effects of CO2 enrichment were even more pronounced than the effects of EBR pretreatment for the photosynthetic genes. Moreover, the changes of antioxidant enzymes activity and lipid peroxidation further confirmed that the chlorpyrifos exposure induced the oxidative stress, which could be ameliorated by either EBR pretreatment or CO2 enrichment. These results strongly suggest a promising prospect for the practical application of BRs or CO2 enrichment to alleviate the phytotoxicity of pesticides in facility agriculture.

Observed trends in the timing of wet and dry season in China and the associated changes in frequency and duration of daily precipitation

ABSTRACTAn understanding of the changes in precipitation timing, wet days (WD) and duration of extreme wet (dry) spells (WS/DS) is of great significant merit in the management of water resources and agricultural activities. In this study, the spatial features of trends in these precipitation characteristics over China during 1960–2013 were investigated. The timing of wet‐/dry‐season exhibited significant shift across the whole China. The timings of wet season showed significant delaying trends over the middle and lower Yangtze River basins and earlier onset trends over northern China, with the rate up to 1 month per 50‐years, which is partly due to the changes in East Asian summer monsoon circulation. Meanwhile, the timings of dry season over the middle and lower Yangtze River basins exhibited prominent earlier trends, combined with the delayed trends of wet season occurrence, resulted in a reduced transition period from wet season to dry season. Accompanying the pronounced shift of the occurrence time of wet‐/dry‐seasons, WD and duration of extreme WS/DS in wet‐/dry‐seasons also showed significant change. Predominantly negative trends of wet‐season WD largely contributed to the deceasing annual WD in the regions east of 100°E. The shortening of extreme dry‐season DS was evident over Northeast China and lower Yangtze River; while the decrease of extreme wet‐season WS was observed over the southern China, and these changes may help to reduce the corresponding risk of drought and flood, respectively. Southwest China showed robust less WD and prolonging DS on both annual and seasonal basis, and thus may enhance the risk of drought in this region.

Meridional Propagation of the 30- to 60-day Variability of Precipitation in the East Asian Subtropical Summer Monsoon Region: Monitoring and Prediction

ABSTRACTThe meridional propagation of the 30- to 60-day intraseasonal variability (ISV) of precipitation in the East Asian subtropical summer monsoon (EASSM) region and its monitoring and prediction are investigated in the current study. Based on a multivariate empirical orthogonal function (MV-EOF) analysis of precipitation and relative vorticity at 700 hPa in East Asia, a bivariate index referred to as the EASSM-ISV index is designed using the two leading MV-EOF modes, with the objective of real-time monitoring of the 30- to 60-day variability of precipitation in the EASSM region. It is found that this index, with its eight phases, can explain the meridional propagation of the 30- to 60-day ISV in precipitation and circulation in the EASSM region. Based on a singular value decomposition technique, a statistical forecast model is developed in which the EASSM-ISV indices from the preceding five pentads are used to predict the indices in five pentads in the future. Meanwhile, the indices are used to predict the meridional propagation of the 30- to 60-day precipitation anomaly in the EASSM region. This model thus provides a useful tool for intraseasonal prediction of precipitation during the rainy season in China.

Performance evaluation of the simulated daily average temperature series in four seasons in China by Beijing Climate Center climate system model

In the present paper, the detrended fluctuation analysis (DFA) method is first used to analyze the daily average temperature records in four seasons in China, and the results show that the seasonal temperature records exhibit long-range correlation in China, especially in Xinjiang and Xizang in western China. Based on the long-range correlation in observational temperature records, we use DFA to evaluate the performances of the simulated daily average temperature series in four seasons in China by Beijing Climate Center climate system model (BCC_CSM) (1.1 m), and find that the BCC_CSM (1.1 m) can reflect the long-range correlations in different seasons. In general, the simulated results are best in spring except for the bad performance in Jiangnan. In summer, the simulation performance is poor in middle-east China and most areas in Tibet, especially in the southern North China, western Huanghai, Jiangnan and South China. The long-rang correlation of the simulated data for autumn is stronger in Northeast China, southeast North China, while weaker in the most of Northwest China. In winter, except for the eastern seaboard, the simulated long-range correlations of daily temperature are weaker than that of observational records in most China. And the simulated performance is poor in Northwest China, Southwest China, northern South China, southern Jiangnan and northern Northeast China, especially in the western Tibet.

Characteristics of K Nutrient Input/Output and its Balance for Wheat Season in China

In this study, the input and output parameters of potassium (K) for wheat season were collected from 2000 to 2011 to evaluate the nutrient cycling and balance in North Central China, the Middle and Lower Reaches of the Yangtze River and Northwest China. The results showed that the K fertilizer application rates for each region were 74.7, 102.9 and 50.6 kg K/ha, the K brought from previous crop were 99.5, 19.8 and 23.4 kg K/ha, and brought from seeding were 1.0, 0.8 and 0.7 kg K/ha, respectively. The K input from atmospheric deposition and irrigation were all considered zero. The K uptake by harvest in above-ground plant in North Central China, the Middle and Lower Reaches of the Yangtze River and Northwest China were 131.8, 159.9 and 119.8 kg K/ha. As a result, The K balance in North Central China showed surplus by 43.6 kg/ha, while in the Middle and Lower Reaches of the Yangtze River and Northwest China, the K balance were both deficiency by 36.4 and 45.1 kg/ha, even though it did not affect the crop yield. While it is suggested that we need to adjust the K fertilizer application in a long term, in order to maintain the sustainable soil fertility.

Burning in agricultural landscapes: an emerging natural and human issue in China

Burning is one of the most widely used methods for removing crop residues during harvest seasons. It cleans fields faster and costs less in comparison to other residue removal methods. Agricultural burning, however, has been recently limited or banned during harvest seasons in China, mainly due to the air quality and human health concerns raised from its use. This paper reviews recent studies on the burning of agricultural landscapes in China to understand the natural (environmental and ecological) and human (economic and social) impacts and identifies uncertainties, gaps, and future research needs. The total annual crop straw output in China is more than 600 billon kg, with about 110, 130, and 230 billion kg coming from rice, wheat, and corn, respectively. Agricultural burning removes about one-fourth of total crop straw and emits about 140–240, 1.6–2.2, and 0.5–0.14 billion kg of CO2, PM2.5, and black carbon, respectively. Agricultural burning accounts for upto half of the total PM10 concentrations in the major burning regions during harvesting periods. Burning emissions contribute to regional haze and smog events. Therefore, limiting or banning agricultural burning is a necessary measure for reducing air pollution in China. The estimations of total burned crop straw amounts and emission factors are the major uncertainty sources for emission estimates. More studies are needed to better describe the smoke plume rise, dispersion, and interactions with weather and climate and to simulate the ecological impacts of agricultural burning. Effective alternatives need to be explored in order to provide solutions for farmers to remove agricultural residues in the wake of the burning ban.

Advancing Seasons in China

Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.

Characteristics of Hospitalized Cases with Influenza A (H1N1)pdm09 Infection during First Winter Season of Post-Pandemic in China

BackgroundInfluenza A (H1N1)pdm09 (2009 H1N1) re-circulated as the predominant virus from January through February 2011 in China. National surveillance of 2009 H1N1 as a notifiable disease was maintained to monitor potential changes in disease severity from the previous season.Methodology/Principal FindingsTo describe the characteristics of hospitalized cases with 2009 H1N1 infection and analyze risk factors for severe illness during the 2010–2011winter season in China, we obtained surveillance data from hospitalized cases with 2009 H1N1 infection from November 2010 through May 2011, and reviewed medical records from 701 hospitalized cases. Age-standardized risk ratios were used to compare the age distribution of patients that were hospitalized and died due to 2009 H1N1 between the 2010–2011winter season to those during the 2009–2010 pandemic period. During the 2010–2011 winter season, children less than 5 years of age had the highest relative risk of hospitalization and death, followed by adults aged 65 years or older. Additionally, the relative risk of hospitalized cases aged 5–14 and 15–24 years was lower compared to children less than 5 years of age. During the winter season of 2010–2011, the proportions of adults aged 25 years or older for hospitalization and death were significantly higher than those during the 2009–2010 pandemic period. Being male, having a chronic medical condition, delayed hospital admission (≥3 days from onset) or delayed initiation of antiviral treatment (≥5 days from onset) were associated with severe illness among non-pregnant patients ≥2 years of age.Conclusions/SignificanceWe observed a change in high risk groups for hospitalization for 2009 H1N1 during the winter months immediately following the pandemic period compared to the high risk groups identified during the pandemic period. Our nationally notifiable disease surveillance system enabled us to understand the evolving epidemiology of 2009 H1N1 infection after the pandemic period.

Predicting Western Pacific Subtropical High Using a Combined Tropical Indian Ocean Sea Surface Temperature Forecast

Weather and climate in East China are closely related to the variability of the western Pacific subtropical high(WPSH), which is an important part of the Asian monsoon system. The WPSH prediction in spring and summer is a critical component of rainfall forecasting during the summer flood season in China. Although many attempts have been made to predict WPSH variability, its predictability remains limited in practice due to the complexity of the WPSH evolution. Many studies have indicated that the sea surface temperature(SST) over the tropical Indian Ocean has a significant effect on WPSH variability. In this paper, a statistical model is developed to forecast the monthly variation in the WPSH during the spring and summer seasons on the basis of its relationship with SST over the tropical Indian Ocean. The forecasted SST over the tropical Indian Ocean is the predictor in this model, which differs significantly from other WPSH prediction methods. A 26-year independent hindcast experiment from 1983 to 2008 is conducted and validated in which the WPSH prediction driven by the combined forecasted SST is compared with that driven by the persisted SST. Results indicate that the skill score of the WPSH prediction driven by the combined forecasted SST is substantial.

Effectiveness of 1,3-dichloropropene as an alternative to methyl bromide in rotations of tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) in China

Replicated field trials were conducted to determine the effect of 1,3-dichloropropene (1,3-D) as a potential alternative for methyl bromide (MeBr) in tomato–cucumber rotations in two successive cropping seasons in China. Fumigation with MeBr (400 kg ha−1), three 1,3-D doses (180, 120 and 90 l ha−1), an avermectin dose (187.5 g ha−1) and an untreated control were compared. Tomato data revealed that MeBr was generally superior to the treatments involving 1,3-D and avermectin, which in turn were superior to the control, for improving tomato crop yield and inhibiting Meloidogyne incognita, weeds and mortality caused by plant disease. In a successive cucumber crop, all fumigants tested except avermectin, showed significant continual influence in the same plots. In most cases, the highest 1,3-D dose was comparable to MeBr. Overall, in both growth seasons, 1,3-D at the dose of 180 l ha−1 was as effective as MeBr in increasing plant height, yield and in reducing the incidence of soil borne disease, especially in maintaining excellent M. incognita control, but it provided only moderate control of weeds. On the basis of these results, combining 1,3-D with other alternatives to MeBr, is recommended for satisfactory control of soil pests in tomato–cucumber rotations in China.

A Study on Surface Validation of the Satellite-derived Vegetation Growing Season in China—A Case of the Temperate Steppe Area and the Warm Temperate Deciduous Broad-leaved Forest Area

Satellite-derived beginning and end dates of growing season at 7 sites of the temperate steppe area and 5 sites of the warm temperate deciduous broad-leaved forest area in China were determined with the measures of seasonal midpoint NDVI(SMN),inflection point by Moulin(MOULIN) and by Zhang(LOGISTIC),and moving average(MA) using NOAA/AVHRR NDVI time series data from 1982 to 2000.The four measures were matched to surface observations and then their stabilities,accuracies,and validities were studied via compare of absolute error distributions,standard deviations,mean absolute errors,and correlation coefficients and so on.The results show that LOGISTIC is the most appropriate of the four measures in determining beginning date of growing season in both the steppe area and the forest area.As to satellite-derived end date of growing season in the steppe area,SMN performs best,followed by LOGISTIC with the senescence point defined as end date.In the forest area,of the four satellite-derived end date of growing season measures,LOGISTIC with the dormancy point defined as end date,is the most preponderant one.This paper provided a typical case and method to surface validation of the satellite-derived vegetation growing season and selection of various measures.

Spatial modeling of the Ulmus pumila growing season in China’s temperate zone

To reveal the ecological mechanism of spatial patterns of plant phenology and spatial sensitivity of plant phenology responses to climate change, we used Ulmus pumila leaf unfolding and leaf fall data at 46 stations of China’s temperate zone during the period 1986–2005 to simulate 20-year mean and yearly spatial patterns of the beginning and end dates of the Ulmus pumila growing season by establishing air temperature-based spatial phenology models, and validate these models by extensive spatial extrapolation. Results show that the spatial patterns of 20-year mean and yearly February-April or September-November temperatures control the spatial patterns of 20-year mean and yearly beginning or end dates of the growing season. Spatial series of mean beginning dates shows a significantly negative correlation with spatial series of mean February-April temperatures at the 46 stations. The mean spring spatial phenology model explained 90% of beginning date variance (p<0.001) with a Root Mean Square Error (RMSE) of 4.7 days. In contrast, spatial series of mean end dates displays a significantly positive correlation with spatial series of mean September-November temperatures at the 46 stations. The mean autumn spatial phenology model explained 79% of end date variance (p<0.001) with a RMSE of 6 days. Similarly, spatial series of yearly beginning dates correlates negatively with spatial series of yearly February-April temperatures and the explained variances of yearly spring spatial phenology models to beginning date are between 72%–87% (p<0.001), whereas spatial series of yearly end dates correlates positively with spatial series of yearly September-November temperatures and the explained variances of yearly autumn spatial phenology models to end date are between 48%–76% (p<0.001). The overall RMSEs of yearly models in simulating beginning and end dates at all modeling stations are 7.3 days and 9 days, respectively. The spatial prediction accuracies of growing season’s beginning and end dates based on both 20-year mean and yearly models are close to the spatial simulation accuracies of these models, indicating that the models have a strong spatial extrapolation capability. Further analysis displays that the negative spatial response rate of growing season’s beginning date to air temperature was larger in warmer years with higher regional mean February-April temperatures than in colder years with lower regional mean February-April temperatures. This finding implies that climate warming in winter and spring may enhance sensitivity of the spatial response of growing season’s beginning date to air temperature.

Onset of East Asian subtropical summer monsoon and rainy season in China

Here we use harmonic analyses to examine seasonal variations of China land rainfall, low-level winds, and atmospheric heating over East Asia during spring to summer and the associated subtropical summer monsoon activities. Our results indicate that the South China spring rainfall (SCSR) in March is the prophase of East Asian sub-tropical summer monsoon (EASSM), and the onset of EASSM and China summer rainy season starts in early April, characterized by the enhanced rainfall in South China and the seasonal reverse of zonal land-sea thermal contrast in sub-tropical East Asia. The EASSM onset is earlier than that of South China Sea summer monsoon, and it is active in east of 100°E and north of 20°N. Our analyses suggest that the subsequent heating appears over India-China Peninsula in March and South China in April and causes the low-level atmospheric warming and the zonal land-sea thermal contrast seasonal reverse in East Asian subtropics. The atmospheric heating over South China is the main force to drive the southwesterly winds, updrafts and strengthen the summer precipitation in South China.

Climate-associated changes in spring plant phenology in China

The timing of phenological events is highly responsive to global environmental change, and shifts in a phenological phase can affect terrestrial ecosystems, agriculture and economics. We analyzed changes in phenology for the spring season in China that occurred between the 1960's and the 2000's using four methods: species-level observations, meta-analysis, satellite measurements and phenology modeling. Previous analyses have rarely been reported due to sparse observations. Our results suggest that spring in China has started on average 2.88 days earlier per decade in response to spring warming by -4.93 days per degree Celsius over the last three decades. The shift towards an earlier start of spring was faster in two forest biomes (spring started on average 3.90 days earlier per decade) than in three grassland biomes (spring started on average 0.95 day earlier per decade). This difference was probably due to increased precipitation impacts in the grassland biomes. Interannual variations in the start of spring were most likely attributed to annual fluctuations in spring temperature (∼40%) and in large-scale circulation anomalies (∼20%).

Relationship between the Meiyu over the Yangtze-Huaihe River Basins and the Frequencies of Tropical Cyclone Genesis in the Western North Pacific

The relationship between the Meiyu precipitation over the Yangtze-Huaihe River Basins (YHRB) and the frequencies of tropical cyclone (TC) genesis in the western North Pacific (WNP) for the period 1951-2006 has been investigated in the present paper. The results have shown that there exists a significant negative correlation between them, which is due to the fundamental changes in monsoonal airflows and associated moisture transports over East Asia and the WNP. In the years with fewer TCs genesis, the location of the main body of the subtropical high over the WNP is farther west and south, and its intensity is abnormally stronger. The monsoon trough also shifted farther west, with a weaker intensity. Under this condition, the monsoon flow and the corresponding moisture transport can not extend eastward down to the WNP, but turns to the East Asian region along the western flank of the subtropical anticyclone over the South China Sea (SCS). Meanwhile, the westerlies at mid-latitudes are located farther south with a stronger intensity. This kind of circulation conditions is favorable for the convergence of the dry and cold air from the mid- and high latitudes and the warm and moist air from the low latitudes over the YHRB, and leads to more precipitation there.In the years with more TCs, the subtropical high over the WNP is located farther north and east, with its intensity being weaker. The monsoon trough zonally extends eastward down to the open sea of the WNP. Most of the monsoon flow and the associated moisture transport from the tropical Indian Ocean can all the way reach the WNP, with a smaller proportion turning northward to the East Asian Meiyu region over the SCS, which is favorable for the genesis and development of TC in the WNP. At the same time, the location of the mid-latitude westerlies is farther north and its intensity is weaker, which is unfavorable for the occurrence of the precipitation over the YHRB. This kind of negative correlation relationship will be conducive to the seasonal forecast of the TC and the Meiyu during the rainy season in China.

Variability and Trends of High Temperature, High Humidity, and Sultry Weather in the Warm Season in China during the Period 1961–2004

Abstract Using the daily maximum air temperature and mean humidity observations at 394 surface weather stations across China, the changes in the annual number of days of high temperature weather (HTW), high humidity weather (HHW), and sultry weather (STW) in China over the period 1961–2004 are studied. The results indicate that there were considerable spatial differences and temporal variability of HTW, HHW, and STW across China. Under a climatic mean condition, a notable feature is that southeastern China is the region of collocation of high values of the annual number of days of HTW, HHW, and STW, as well as the region of the most significant variabilities of these parameters. About 55% of the stations in China have increasing trends of the annual number of days of HTW. Most stations in China show decreasing trends of the annual number of days of HHW and are mainly located either in the area south of 30°N or in northern and northeastern China. The stations with increasing trends of the annual number of days of STW are mainly located in northern China, while the stations that have decreasing trends are primarily located in southern China. The analysis results suggest that the variability of the annual number of days of STW corresponds mainly to HTW, and less to HHW. The change in the East Asian monsoon may be responsible for the changes of these statistics in extreme weather in China.

Spatiotemporal change in China’s climatic growing season: 1955–2000

The timing, length, and thermal intensity of the climatic growing season in China show statistically significant changes over the period of 1955 to 2000. Nationally, the average start of the growing season has shifted 4.6-5.5 days earlier while the average end has moved 1.8-3.7 days later, increasing the length of the growing season by 6.9-8.7 days depending on the base temperature chosen. The thermal intensity of the growing season has increased by 74.9-196.8 growing degree-days, depending on the base temperature selected. The spatial characteristics of the change in the timing and length of the growing season differ from the geographical pattern of change in temperatures over this period; but the spatial characteristics of change in growing degree-days does resemble the pattern for temperatures, with higher rates in northern regions. Nationally, two distinct regimes are evident over time: an initial period where growing season indicators fluctuate near a base period average, and a second period of rapidly increasing growing season length and thermal intensity. Growing degree-days are highly correlated with March-to-November mean air temperatures in all climatic regions of China; the length of the growing season is likewise highly correlated with March-to-November mean air temperatures except in east, southeast and southwest China at base temperature of 0A degrees C and southeast China at base temperature of 5A degrees C. The growing season start date appears to have the greater influence on the length of the growing season. In China, warmer growing seasons are also likely to be longer growing seasons.

Response of the starting dates and the lengths of seasons in Mainland China to global warming

The climatic seasons in China, defined by station-specific daily temperature measures, have changed substantially during the past decades. In the majority of the country, the length of summer has extended and the length of winter has shortened since the 1950s. These changes in the lengths of seasons are linked to the changes in the starting dates of seasons. Namely, the starting date of summer has advanced and the starting date of winter has shifted back. Averaged across the whole country, the starting date of summer has been brought forward by 5.8 days and the season has extended 9 days. On the other hand, the starting date of winter has been delayed by 5.6 days and the season has shortened by 11 days. The changes for spring and fall are relatively smaller. Particularly, spring has started earlier by 5.7 days but shortened by 0.3 day, and fall has started later by 3.2 days but lengthened by 2.3 days. The changes in seasons exhibit apparent regional differences. They are more significant in the north than in the south where the trend of some local changes in seasons is opposite to that of the rest of the country.