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Li Y.,Nanjing University of Information Science and Technology | Li Y.,Chongqing Institute of Meteorological science | Xu H.,Nanjing University of Information Science and Technology | Liu D.,Chongqing Municipal Meteorological Bureau
Acta Meteorologica Sinica | Year: 2011

The spatial-temporal features of the extremely severe drought and the anomalous atmospheric circulation in summer 2006 are analyzed based on the NCEP/NCAR reanalysis data, the characteristic circulation indices given by the National Climate Center of China, and the daily precipitation data of 20 stations in the east of Southwest China (ESC) from 1959 to 2006. The results show that the rainless period started from early June and ended in early September 2006 with a total of more than 80 days, and the rainfall was especially scarce from around 25 July to 5 September 2006. Precipitation for each month was less than normal, and analysis of the precipitation indices shows that the summer precipitation in 2006 was the least since 1959. The extremely severe drought in the ESC in summer 2006 was closely related to the persistent anomalies of the atmospheric circulation in the same period, i.e., anomalies of mid-high latitude atmospheric circulation, western Pacific subtropical high (WPSH), westerlies, South Asian high, lower-level flow, water vapor transport, vertical motion, and so on. Droughts usually occur when the WPSH lies anomalously northward and westward, or anomalously weak and eastward. The extreme drought in summer 2006 was caused by the former. When the WPSH turned stronger and shifted to the north and west of its normal position, and the South Asian high was also strong and lay eastward, downdrafts prevailed over the ESC and suppressed the water vapor transfer toward this area. At the same time, the disposition of the westerlies and the mid-high latitude circulation disfavored the southward invasion of cold air, which jointly resulted in the extremely severe drought in the ESC in summer 2006. The weak heating over the Tibetan Plateau and vigorous convective activities over the Philippine area were likely responsible for the strong WPSH and its northwestward shift in summer 2006. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2011.

Wang J.,China Agricultural University | Wang E.,CSIRO | Yin H.,National Climate Center | Feng L.,China Agricultural University | Zhang J.,Chongqing Institute of Meteorological science
Agricultural and Forest Meteorology | Year: 2014

Quantifying the changes in crop potential yields and yield gaps is essential to determine the yield-contributing and yield-limiting factors and enhance crop productivity. Here we combine simulation modeling and long-term maize yield records (1981-2009) from 10 sites to investigate the changes in maize yield potential, actual yield and yield gaps in the past three decades in the North China Plain (NCP). The cultivar parameters in the APSIM-maize model were derived based on the recorded flowering and maturity dates at each site, and the simulation results of calibrated model was able to explain >63% of the variations in recorded maize grain yield across the 10 sites. Potential maize yield simulated under sufficient water and nitrogen supply showed a general declining trend, significantly (P<. 0.01) at half of the study sites. This was mainly caused by the declining radiation together with increasing temperature, particularly during the pre-flowering period. Continuous adoptions of new maize varieties helped to maintain the pre-flowering periods at some sites and to extend post-flowering periods at most sites. This, together with increasing planting density, led to continuous increase in maize yields. As a result, maize yield gaps continued to shrink (P< 0.05) at all the sites except for Zhengzhou, with a rate ranging from -116.8 kg/ha. a to -356.5 kg/ha a across sites. At two of the studied sites, the maize potential yield had already been achieved. While application of irrigation and nitrogen fertilizers has been managed at near optimal level already, other new technological breakthroughs will be needed for future advance of maize yield. © 2014 Elsevier B.V.

Wu W.,Southwest University | Fan L.,Chongqing Institute of Meteorological Science | Li M.,Southwest University | Liu H.,Southwest University | Li Y.,Agricultural Commission of Wanzhou District
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2012

The records of daily solar radiation (Rs, MJ·m -2·d -1) are the important inputs for crop simulation models. However, for some model users, Rs at longer temporal intervals are more available than that at daily scale. The objective of this study was to analyze the sensitivity of simulated crop growth and production using CERES-Maize and GROPGRO-Soybean, two widely used crop growth models, to uncertainty in Rs at different time scales (5-day, 10-day, and monthly). Daily radiation data (1961-1990) from Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) for the state of Georgia, USA were used to create 5-day, 10-day, and monthly mean daily Rs data sets. Datasets related to daily Rs were used as background baselines. The overall performance of the models was not significantly affected by Rs under the studied time scales. Within locations, the simulated days to anthesis and grain yields from 5-day, 10-day, and monthly Rs were close to that from daily Rs for maize and soybean under rainfed and irrigated conditions, respectively. Mean values of relative mean bias error (RMBE), mean bias error (MBE) and root mean square error (RMSE) of the simulated days to anthesis were 0, 0 and 3.5 d for the two crops under the studied scenarios, respectively. The simulated yields were underestimated for maize and overestimated for soybean using 5-day, 10-day, and monthly Rs for both rainfed and irrigated conditions, respectively. Under rainfed and irrigated conditions, the average RMBE and RMSE were -0.59%, 120 kg/hm 2 and -0.52%, 129 kg/hm 2 for maize yield, and 5%, 152 kg/hm 2 and 4.7%, 165 kg/hm 2 for soybean, respectively. Short-term bias in the difference between evaluated time scales and daily scale could affect the outputs of the crop models. Under the scenarios evaluated, CGOPGRO-Soybean model showed higher sensitivity to changes in multi-temporal Rs and water regimes than CERES-Maize model. Based on the results of this study, it can be concluded that 5-day, 10-day, and monthly mean daily Rs could be used as an input for crop growth simulation models when daily Rs are not available.

Liu Z.,Southwest University | Zhang J.,Chongqing Institute of Meteorological science | Luo H.,Southwest University | He Y.,Chongqing Institute of Meteorological science
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

Maize, as a major grain crop in Southwest China, has contributed significantly to total grain production in the region. Drought is the most prominent agro-meteorological disaster which poses serious threat to maize production. Therefore, it is important to analyze its temporal and spatial distribution characteristics and occurring regularities to provide technical supports for disaster prevention and reasonable layout of maize production in Southwest China. In this study, daily meteorological data, collected from 60 stations in maize planting areas of Southwestern China during 1960-2010, were used to calculate the Agricultural Reference Index for Drought (ARID) which computed daily and based on three important factors (soil, vegetation and atmosphere). The spatial distribution of drought frequency at maize growth periods and annual variations of drought in recent 50 years were analyzed to validate the application of ARID in this region. The results showed there were obviously regional characteristics in recent 50 years. Drought happened most frequently in north center and northeast of YunNan and south of SiChuan, followed by GuanYuan of SiChuan areas, mountains of southwestern SiChuan, northwestern YunNan, YuanJiang and its surrounding areas. Areas with the lowest incidence of drought mainly located in the most regions of ChongQing, the north of GuiZhou and other regions. Drought occurred with the highest frequency at the stage of emergence to jointing and the lowest frequency at the stage of tasseling to filling. In addition, with the development of the growth, drought occurrence had the tendency to move to the east. ARID extremely differed in sub-regions of Southwestern China during maize growing periods. In general, light drought happened in higher frequency than moderate and severe drought. Specifically, only a few regions were moderate drought or fluctuated between light drought and moderate drought. The inter-annual change feature of ARID showed that drought was light in 1980s and became more serious at the beginning of the 21st century.

Chen Y.,Chongqing Institute of Meteorological science | Tang Y.,Chongqing Institute of Meteorological science | You Y.,Chongqing University
Advanced Materials Research | Year: 2012

In this paper, serial data of daily Normalized Difference Vegetation Index (NDVI) cloudless day from March to November 2011 in Chongqing was used, and Time-series NDVI such as a period of ten days' (or monthly/yearly) maximum NDVI under cloudless day was obtained. The serial NDVI with different period of time were divided into 6 characteristic districts according to altitude. The results of the analysis showed as following: growth of vegetations had obvious seasonal variation that the number of NDVI was gradual increase during March to April, and was bigger during May to September, gradually decreased after October. From mid-August to mid-September, and the NDVI of the Middle and West of Chongqing was less than normal owing durative drought. The NDVI was increased with increasing of highness and NDVI increaseed rapidly below 1500m while increased slowly above 1500m that showed better was the ecological environment, higher was the altitude. © (2012) Trans Tech Publications, Switzerland.

Chen Y.,Chongqing Institute of Meteorological science | You Y.,Chongqing University
Applied Mechanics and Materials | Year: 2013

In this paper, MODIS-250m vegetation index from first 10-day of March to last 10-day of November in 2010and 2011, land use data and the yield data from 9 counties such as Jiangjin, Wanzhou, Fengdu, Liangping, Qijiang, Liangping, Fuling, Yunyang, Kaixian, Wixi in Chongqing were used. Based on GIS,RS technique and NDVI analysis results, the rice planting area was extracted. Four key growth period of rice such tillering, jointing, heading and milk were selected to establish dynamic assessment model. In nine counties, the average relative error of the remaining 8 counties was between 5.36%-17.09%, and the mean was 12.31% except Qijiang that estimation results and actual yield deviation was too large. The results show that building rice yield estimation model using normalized difference vegetation index was feasible that can realize the dynamic yield estimation of rice. © (2013) Trans Tech Publications, Switzerland.

Yang S.,Chongqing Institute of Meteorological science | Liu C.,Chongqing Environmental Monitoring Center | Gao Y.,Chongqing Institute of Meteorological science
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

This paper selected 6S (second simulation of the satellite signal in the solar spectrum) model with dark pixel method to inversion aerosol optical depth by MODIS data, and got the spatial distribution and the temporal distribution of Chongqing urban area. By comparing with the sun photometer and API data, the result showed that the inversion method can be used in aerosol optical thickness monitoring in Chongqing urban area. © 2015 SPIE.

Fan L.,Chongqing Institute of Meteorological science | Wang Y.,Chongqing Academy of Agricultural science | He Y.K.,Chongqing Institute of Meteorological science
Advanced Materials Research | Year: 2014

With the demand of the stem mustard premature bolting forecast in Fuling area, from the biology characteristics of stem mustard's early bolting, the paper analyzes the two-season planting test data of stem mustard in 2011, and screens the significant meteorological factors that affecting the stem mustard premature bolting, which is average air temperature of the first 9-12 days after sowing, the maximum temperature and precipitation days in the stage of sowing - 3 leaf, and then establishes the prediction model of stem mustard premature bolting by Logistic equation. Finally, the planting test data in 2012 are used to test the model, which can better simulate the occurrences of stem mustard premature bolting, and forecast has good feasibility. © (2014) Trans Tech Publications, Switzerland.

Zhang J.,Chongqing Institute of Meteorological science | He Y.,Chongqing Institute of Meteorological science
Advanced Materials Research | Year: 2012

Taking the day numbers of daily average temperature ≥30°C and the day numbers of daily maximum temperature ≥35°C as the index of high temperature disaster, the occurrence regularity of high temperature disaster for June to September was analyzed from 1961 to 2010 in Chongqing. The results showed that there was a large inter-decadal variation in occurrence of high temperature disaster. The most severe year of high temperature disaster was the year of 2006, while the year of 1987 is the lightest one. The general trend was that it was the lowest one in the 1980s and gradually increased in the 1990s, and reached the highest value in the 2000s. The spatial distribution of the day numbers of daily average temperature ≥30°C was the same as that of the day numbers of daily maximum temperature ≥35°C. The highest values were distributed at the areas of Kaixian, Yunyang, Wushan in the Northeast part and Fengdu, Fuling in the middle part and Banan,Shapingba,Beibei in urban district and Qijiang in the southwest part. The lowest values were distributed at the areas of Xiushan,Youyang,Qianjiang in the southeast part and Chengkou,Fengjie in the northeast part and Dazu,Rongchang in the west part. © (2012) Trans Tech Publications, Switzerland.

Zuo X.,Chongqing Institute of Meteorological Science
Journal of Natural Disasters | Year: 2010

Emergency rescue is a critical part of emergency management. Based on the case study of the emergency rescue during the landslide in Wulong County, Chongqing Municipality this paper analyzes the current condition of emergency rescue during natural disasters in China, indicates the main problems existing in the current rescue status, and discusses solutions to improve emergency rescue capability for natural disasters.

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