Time filter

Source Type

Xiang D.,Wuhan University | Liu L.,Wuhan University | Han T.,Institute of Arid Meteorology | Han T.,Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province | Han T.,Key Open Laboratory of Arid Climatic Change and Reducing Disaster of CMA
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/ Geomatics and Information Science of Wuhan University | Year: 2010

The FY-3A satellite is an obit meteorological satellite which can provide the globalizational, three-dimensional, multi-spectral remote sensing images. One of the FY-3A missions is monitoring the natural disaster and the change of environment all over the world. We analyze the ability of drought monitoring using the FY-3A MERSI data. First, the art of status of FY-3A satellite is introduced and the potential ability in drought monitoring is discussed. Second, the FY-3A MERSI and MODIS data are preprocessed and analysed. Finally, the relativel precision between the results of FY-3A MERSI and MODIS data are analyzed. The results of experiment indicate that the FY-3A MERSI data can improve the drought monitoring ability in same spatial and spectral resolution aspects. Source

Xin J.,Chengdu University of Information Technology | Xin J.,CAS Institute of Atmospheric Physics | Gong C.,Institute of Arid Meteorology | Gong C.,Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province | And 4 more authors.
Atmospheric Research | Year: 2016

The optical properties of dust aerosols were measured using narrow-band data from a portable sun photometer at four desert and semi-desert stations in northwestern China from 2004 to 2007. Ground-based and satellite observations indicated absorbing dust aerosol loading over the region surrounded by eight large-scale deserts. Radiation forcing was identified by using the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model. The ranges of annual mean aerosol optical depth (AOD), Angström exponents, and single-scattering albedo (SSA) were from 0.25 to 0.35, from -0.73 to 1.18, and from 0.77 to 0.86, respectively. The ranges of annual mean aerosol direct radiative forcing values at the top of the atmosphere (TOA), mid-atmosphere, and on the surface were from 3.9 to 12.0, from 50.0 to 53.1, and from -39.1 to -48.1W/m2, respectively. The aerosols' optical properties and radiative characteristics showed strong seasonal variations in both the desert and semi-desert regions. Strong winds and relatively low humidity will lead dust aerosols in the atmosphere to an increase, which played greatly affected these optical properties during spring and winter in northwestern China. Based on long-term observations and retrieved data, aerosol direct radiative forcing was confirmed to heat the atmosphere (50-53W/m2) and cool the surface (-39 to -48W/m2) above the analyzed desert. Radiative forcing in the atmosphere in spring and winter was 18 to 21W/m2 higher than other two seasons. Based on the dust sources around the sites, the greater the AOD, the more negative the forcing. The annual averaged heating rates for aerosols close to the ground (1km) were approximately 0.80-0.85K/day. © 2015 Elsevier B.V. Source

Yu L.,Northwest University for Nationalities | Yu L.,Institute of Arid Meteorology | Longqing L.,University of Sichuan | Qiang Z.,Institute of Arid Meteorology | And 6 more authors.
Chemistry and Ecology | Year: 2013

The aim of the present study was to investigate the possible effects of temperature on cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) accumulation in five vegetable species collected at different sites (Shuichuan, Beiwan, Dongwan and Wufe) in northwest China. The meteorological data of air and soil temperatures were recorded daily during the period from sowing to harvest for the five vegetables. The air and soil temperatures affected the capacity of pumpkin, cabbage, brassica napus and Chinese cabbage to accumulate Zn, Cd, Cu and Pb. Principal component analysis showed that temperature, photosynthetic and physiological factors all contributed to the soil-plant transfer properties of DTPA-extractable heavy metals. Temperature played a more important role in Cd, Pb, Cu and Zn accumulation in four vegetables in this semiarid area. However, the enormous surface area of spinach was likely to elevate heavy metal loads owing to atmospheric deposits. For most vegetables studied, there was a striking dissimilarity in the uptake and translocation ability of Cd, Zn and Cu in soil, but similar accumulation to translocation for Pb in soil. © 2013 Copyright Taylor and Francis Group, LLC. Source

Qi W.,Gansu Agricultural University | Xiang R.,Gansu Agricultural University | Xingyang S.,Gansu Agricultural University | Guangrong H.,Gansu Agricultural University | And 4 more authors.
Field Crops Research | Year: 2014

Drought, water loss and soil erosion are the main factors limiting agricultural production in semi-arid regions of China. A field study was conducted to determine (1) the runoff efficiencies of different ridge widths (30, 45 and 60cm) covered with different materials (common plastic film, biodegradable mulching film and manual compacted soil) and (2) the effects of different ridge-furrow ratios (30:60, 45:60 and 60:60) and ridge-covering materials on soil water storage, topsoil temperature, hay yield, grain yield and water use efficiency (WUE) of oats in ridge-furrow rainwater harvesting (RFRH) system at the Dingxi Agri-meteorological station, during 2 consecutive years of 2012 and 2013. Average runoff efficiency was 18%, 20%, 22%, 71%, 77%, 83%, 76%, 77% and 84% for SR30, SR45, SR60, BMR30, BMR45, BMR60, CMR30, CMR45 and CMR60 (SR, BMR and CMR were ridges with compacted soil, covered with biodegradable mulch film and common plastic film, respectively, and subscript numbers 30, 45 and 60 stand for ridge widths (cm)) over 2 years, respectively. The field experiment using oats as an indicator crop showed that mulching materials and ridge widths had distinct effects on topsoil temperature on the top of the ridges, but not in the bottom of the furrows. The soil water storage in the 140cm depth of soil at the bottom of furrows increased with increasing ridge widths and in the order of CMR≈BMR>SR>FP (FP was the flat planting). The total precipitation was 414.4mm in 2012 and 448.8mm in 2013, which were higher than the average of rainfall (388.1mm), leading to a significant increase of hay and grain yield in CMR, and an equivalent of hay and grain yield in BMR compared with FP in most cases. In the SR system, the positive effects of rainwater harvesting could not compensate for the negative effects of planting area reduction resulting in decrease in hay and grain yield. Compared with FP, the average grain yield decreased by 19%, 27% and 34% for SR30, SR45 and SR60, and increased by 6%, 4%, 1%, 12%, 9% and 6% for BMR30, BMR45, BMR60, CMR30, CMR45 and CMR60 over 2 years, respectively. The WUE of SR, BMR and CMR was 1.31, 1.41 and 1.47 times greater than that in FP over 2 years, and increased with increasing ridge width. The optimum furrow width was 32-38cm for CMR and was 30-34cm for BMR. Future study is needed to investigate the impact of RFRH on crop production, WUE and economic benefit under different precipitations, soil types, slopes and plant species using biodegradable mulching materials. © 2014 Elsevier B.V. Source

Feng J.,Institute of Arid Meteorology | Feng J.,Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province | Li Y.,Institute of Arid Meteorology | Li Y.,Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province | And 3 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2011

Based on the data of meteorological and hydrological collected from 1961 to 2004, the cause have been analyzed on the lowest runoff in the upper reaches of yellow River in recent years in this paper. The results indicate runoff recorded exhibited slight decrease trend from 1961 to 2004, but there is a notable decrease trend of runoff since 1990. It is noteworthy that low stream continued 15 years from 1990 to 2004, besides 1993 and 1999. Moreover, 9 year amount of runoff anomalous percentage below - 30% among 13 years of the low runoff years, account for 69%, contrast to 6.5% from 1736 to 1998. The paper has discussed the cause of the persistent low flow in the upper reaches of Yellow River in recent years based on the data of general circulation of atmosphere, sea-surface temperature(SST), sensible heat flux over Tibetan Plateau, precipitation, temperature, wind speed, sunshine time, amount of evaporation and maximum depth of frozen ground since 1990. The main cause is showed to be persistent low precipitation since 1990, which may be caused by NAOI maintained positive height phase in winter, East Asian big trough leaning depth, West Pacific Ocean subtropical high pressure ridge line position near southerly, greater sensible heat flux in spring and summer over Tibetan Plateau and stronger geothermal fields that easily result in a kind of typical Northwest drought circulation of 500hPa south positive and north negative, west positive and east negative, weak north wind and strong west wind, and deep East Asian trough and strong Xinjiang ridge in summer in East Asian. Secondarily, the reduction of rainy days above 5 mm and steady rainy days, higher temperature and larger evaporation in spring and summer is disadvantageous to create runoff. The results also indicate that the drought of the surface in the basin resulted in the decreasing trend of the runoff. © 2011 IEEE. Source

Discover hidden collaborations