Huang Z.,Yunnan Climate Center
Advances in Climate Change Research | Year: 2011
Factor analysis was used to investigate the changes of dry-wet climate in the dry season in Yunnan during 1961-2007 based on observed data from 15 stations. Three common factors were extracted from the 9 climatic factors. The results showed that the dry-wet climate has evidently changed since the early 1960s. The general trends in the changes of dry-wet climate were described as slight decrease in humidity and gradual enhancement in drought intensity. The climate during 1960s-1980s was under weak-medium drought. But since early 1990s, dry conditions have markedly strengthened and continued due to uneven temporal distribution of rainfall and climate warming.
Zhang J.E.,Meteorological Research Institute of Jiangxi Province |
Xiao H.,Agro meteorological Experiment Station of Jiangxi Province |
Zheng Y.F.,Jiangsu Key Laboratory of Meteorological Disaster |
Wu R.J.,Jiangsu Key Laboratory of Meteorological Disaster |
And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015
The open-top chamber (OTC) is an important device used to study the impact of climate change on ecosystems. These chambers have been widely used in climate change simulation and pollution ecology research. Compared to the conventional closed artificial climate chamber or the newly developed free-air concentration enrichment (FACE) method, the OTC creates a microclimate that is more similar to the atmospheric environment. Moreover, its test gas concentration control is more precise, and its construction and operating costs are lower. Our research results indicated that microclimatic elements inside and outside the OTC are different. Although much research has been carried out on microclimatic elements inside and outside the OTC, and improvements have been made based on these research results, there are only a few reports on the growth and photosynthetic response of plants to these microclimatic differences. This study aimed to evaluate the photosynthetic response of winter wheat (Triticum aestivum L.) grown inside (T1) and outside (T2) an OTC, using the plants of a modern cultivar, ‘YangMai16.’ Gas exchange, photosynthetic pigment content, and chlorophyll fluorescence parameters were evaluated. The test field was located at the Agricultural Meteorological Experiment Station of Nanjing University of Information Science and Technology, China (32º 03′ N, 118º51′ E). The seeds were sown on November 5, 2009, by drilling, with a seeding rate of 220.5 kg/hm2, and plants were harvested on May 31, 2010. The daily mean temperature and relative humidity inside the OTC used in our experiments were 8.9% and 3.3% higher, respectively, than those of the atmospheric environment; however, total radiation was 20.4% lower. The differences in microclimatic elements inside and outside the OTC used in this study were similar to those recorded by other groups.Our results indicated that the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), max photo-synthetic rate (Pm), and half-saturation light intensity (Ik) of T1 were significantly higher than those of T2 (P<0.05). Before the filling stage, the apparent quantum yield (AQY) of T1 was significantly higher than that of T2, whereas transpiration rate (Tr) and dark respiratory rate (Rd) were significantly lower (P < 0.05). After the filling stage, the results reversed. The chlorophyll and carotenoid contents of T1 were significantly higher than those of T2 during most of the growth stages P < 0.05). The basic fluorescence yield (Fo) and dark-adapted maximum fluorescence yield (Fm) values of T1 were higher than those of T2, but there was no difference in the maximum photochemical capacity of PSII (photosystem II) (Fv / Fm) between T1 and T2 during most of the growth stages. In the booting and flowering stages, the photochemical quenching coefficient (qP) of T1 was significantly lower than that of T2 (P<0.05). There was no difference in the quantum yield of photochemical energy conversion in PSII [Y(II)]of T1 and T2 during most of the growth stages. The non-photochemical quenching coefficient (NPQ) and quantum yield of regulated non-photochemical energy loss in PSII [Y(NPQ) ] of T1 were significantly higher than those of T2 after the filling stage (P <0.05), whereas the quantum yield of non-regulated non-photochemical energy loss in PSII [Y(NO) ] was lower. Our results indicate that the gas exchange capability, light response capability, and photosynthetic pigment content of winter wheat grown inside the OTC were higher than those of wheat grown outside. There were no differences in the maximum photochemical capacity and quantum yield of photochemical energy conversion in the PSII of winter wheat grown inside and outside the OTC. In contrast, the fraction of energy dissipated as heat via the regulated photo-protective NPQ mechanism was higher, while the fraction that was passively dissipated in the form of heat and fluorescence was lower, for winter wheat grown inside the OTC. Photo-protection of the photosynthetic apparatus from excess energy in PSII was also better in the winter wheat grown inside the OTC. Our results are expected to help improve OTCs, including the evaluation of data from controversial ecology projects and the application of research knowledge obtained from OTCs to field conditions. © 2015, Ecological Society of China. All rights reserved.
Li Y.,Nanjing University of Information Science and Technology |
Li Y.,Chinese Academy of Meteorological Sciences |
Ren F.,Chinese Academy of Meteorological Sciences |
Ren F.,Jiangsu Collaborative Innovation Center for Climate Change |
And 3 more authors.
Journal of Meteorological Research | Year: 2014
An objective identification technique for regional extreme events (OITREE) and the daily compositedrought index (CI) at 101 stations in Southwest China (including Sichuan, Yunnan, Guizhou, and Chongqing) are used to detect regional meteorological drought events between 1960 and 2010. Values of the parameters of the OITREE method are determined. A total of 87 drought events are identified, including 9 extreme events. The 2009-2010 drought is the most serious in Southwest China during the past 50 years. The regional meteorological drought events during 1960-2010 generally last for 10-80 days, with the longest being 231 days. Droughts are more common from November to next April, and less common in the remaining months. Droughts occur more often and with greater intensity in Yunnan and southern Sichuan than in other parts of Southwest China. Strong (extreme and severe) regional meteorological drought events can be divided into five types. The southern type has occurred most frequently, and Yunnan is the area most frequently stricken by extreme and severe drought events. The regional meteorological drought events in Southwest China have increased in both frequency and intensity over the study period, and the main reason appears to be a significant decrease in precipitation over this region, but a simultaneous increase in temperature also contributes. © 2014 The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg.
Yan H.-M.,Yunnan Climate Center |
Li Q.-Q.,National Climate Center |
Yuan Y.,National Climate Center |
Li C.-Y.,PLA University of Science and Technology |
Li C.-Y.,CAS Institute of Atmospheric Physics
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2013
The circulation variation over western North Pacific and the relationship between circulation and tropical Sea Surface Temperature Anomalies(SSTA) were investigated in this paper. The results showed that western North Pacific anticyclone (WNPAC)/cyclone (WNPC) is two significantly anomalous phenomena at mid-low troposphere over western North Pacific, and their variation is related to PJ wave line and zonal wave line at mid-high latitude region of Eurasia. Owing to this interrelation, WNPAC/WNPC can influence the climate over East Asian and Eurasia. The result showed also that the relationship between WNPAC/WNPC in summer and SSTA is obviously asymmetrical. Generally, evident WNPAC occur in summer of feeble El Niño years, and are related with warm SSTA in winter of mature El Niño years over equatorial East Pacific and warm SSTA in spring and summer of weakening El Niño years over Indian Ocean, which further display the important bridge role of WNPAC in El Niño event influence on summer climate over East Asian. But the relationship between obvious WNPC and SSTA in Indian Ocean is not steady. The formation and maintenance of WNPAC are mainly related to anomalous westerlies resulting from thermal contrast between SSTA over Indian Ocean and SSTA over the Pacific. The possible cause of asymmetry is further investigated. The results showed that the thermal contrasts between Indo-Pacific in El Niño and La Niña summer are accordant, which possibly result in asymmetry relationship between WNPAC/WNPC and SSTA.
Yan H.,Yunnan Climate Center |
Yang H.,CAS Institute of Atmospheric Physics |
Yuan Y.,National Climate Center |
Li C.,CAS Institute of Atmospheric Physics |
Li C.,PLA University of Science and Technology
Advances in Atmospheric Sciences | Year: 2011
Using National Centers for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalysis data and monthly Hadley Center sea surface temperature (SST) data, and selecting a representative East Asian winter monsoon (EAWM) index, this study investigated the relationship between EAWM and East Asian summer monsoon (EASM) using statistical analyses and numerical simulations. Some possible mechanisms regarding this relationship were also explored. Results indicate a close relationship between EAWM and EASM: a strong EAWM led to a strong EASM in the following summer, and a weak EAWM led to a weak EASM in the following summer. Anomalous EAWM has persistent impacts on the variation of SST in the tropical Indian Ocean and the South China Sea, and on the equatorial atmospheric thermal anomalies at both lower and upper levels. Through these impacts, the EAWM influences the land-sea thermal contrast in summer and the low-level atmospheric divergence and convergence over the Indo-Pacific region. It further affects the meridional monsoon circulation and other features of the EASM. Numerical simulations support the results of diagnostic analysis. The study provides useful information for predicting the EASM by analyzing the variations of preceding EAWM and tropical SST. © 2011 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.