Based on the brightness temperature observations of AMSR-E in 2005 and 2006, this study attempts to find the
simplest and best drought index for identifying drought areas. Totally 8 candidate drought indices were tested from
the AMSR-E brightness temperature data. Assuming that the NASA AMSR-E soil moisture data obtained from
complicated soil moisture retrieval algorithms are the best currently available soil drought indicator, the computed
index with the best correlation with these soil moisture data should the best drought index. For each of the selected
three stations in Hebei province, the temporal correlations between this drought index and the corresponding
precipitation anomalies were computed for the two years. The spatial variations of this drought index and the
precipitation anomaly were also compared with each other for Hebei province in March 2006. Based on these
comparisons, the selected drought index was found to be useful for monitoring drought. Problems for using satellite
microwave observations and future research needs on microwave drought monitoring are discussed.
In the context of 1960~2003 summertime rainfall and small-sized pan evaporations from 131 stations distributed over NW China covering Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi as well as western Nei Mongolia, and Arctic Oscillation Indices (AOI) we define a homogenized index for aridity or wetness feature, with which to examine the relations between AOI and NW China aridity-wetness regime, indicating their noticeable relations on an interdecadal basis. It is found that during the decade of summer Arctic oscillation stronger than mean, the sea level pressure field shows positive (negative) anomalies over Asian landmass, a stronger anticyclonic anomaly circulation appears at 700 hPa over Lake Baikal and to the south, westerly (northerly) departure emerges in the westerly (monsoon) portion of NW China, as well as over NW China there appears a structure with a low in the west and a high in the east at the 500 hPa height field, suggestive of east-Asian summer monsoon weaker than normal such that westerly flows prevail in the westerly zone of NW China, leading to rainfall more than mean for a wetter climate while in its monsoon area the northerly winds are dominant, with precipitation less than normal, resulting in a climate drier in comparison to mean and v.v. for the decade with summer AO weaker than normal.
By means of a linear tendency estimation scheme and correlation analysis a study is undertaken of change in Zhengzhou climate and phonological response of woody plants thereto, together with relations between meteorological elements (rainfall, sunshine length and mean temperature) and phenological periods investigated. And later, using a least squares polynomial, a fit expression is constructed for the peak phase of flowering in relation to mean temperature over the previous 3 months. Results show that mean temperature is the critical climate factor to the phonological response of the trees except for leaf-falling phase in autumn; temperature inference of phenology has a clear ecological implication in exploring the relation between climate change and phonological response, with which to plan agricultural undertaking and monitor ecological environment on a scientific basis.
Climate yield potential is known to be under great effect of climate factors. Based on multi-yearly climate records and agrometeorological observations and by means of the scheme for calculating yield potential (YP) proposed by Huang Bingwei the authors investigate the distribution of mean climate YP for several representative stations in Henan and averaged availability of climate resources for staple crops in this province, and with Zhengzhou station as the typical station, calculated is made of annual YP of photosynthesis, light-temperature, and light - temperature- water and also YP of wheat and corn related to the above three factors. Wavelet analysis shows that on an annual basis, the photosynthesis YP has quasi-8 yearly periods, light-temperature YP gives quasi-8 and quasi-4 yearly periods, and light- temperature-water YP exhibits quasi-6 and quasi-10-yearly periods. Study is also undertaken of availability of climate resources by wheat and corn in the year and their growth season. Finally, analysis is done of effects of meteorological factors upon yields of the staple crops as well as their availability of the climate resources.
Northwestern China is a semi-arid or arid area in China. Ningnan (or South Ningxia) district is located south of Ningxia Province belong to Northwestern part of China. Climate in this region is more dry and lack of precipitation. Because global climate have been changing, temperature has been increasing and rainfall has been decreasing in South Ningxia. The ecology has been deteriorating, such as vegetation cover destroying, water losing and soil erosion. Therefore, the people who live in South Ningxia have been poor. Recently, Chinese government put into effect on strategy of "great development of Chinese northwest", aiming to improve environmental and ecological conditions and rise people's living standard. South Ningxia district was defined as area of emigration where the measurements of returning land for farming to forestry were taken into account . How to evaluate the plans and measurements is very important to continue to improving local environmental and ecological conditions further. The basic index of evaluation is soil water profit and loss statement while evapotranspiration (ET) is an important component in statement income and outcome of soil water. It is a very complicated problem to estimate evapotranspiration (ET) over large area of natural surface. In this paper, the natural surface was classified as 5 categories based on information from remote sensing, each categories being dealt with special way. Using data of remote sensing and weather stations, the result of regional evapotranspiration over Ningnan(South Ningxia) was given out, and verified and discussing are also made out. The work helps to assess whether or not improve environmental and ecological conditions.
This work was based upon the combination of space- and ground-based data. Sensings at 1.1 km × 1.1 km resolution from the polar-orbiting weather satellite were retrieved by a range of split window algorithms to obtain surface temperatures, which were used to construct a regression equation with minimum surface temperatures (MST) measured at a number of meteorological stations, with the retrievals and measurements corrected by a variational scheme to get gridded MST's. After comparison of errors from these algorithms the best one was selected for retrieving. By use of the retrieved temperatures re-corrected by the variational technique, injury indices and wheat conditions during its growth stages, the regional distribution was prepared of varying-degree cold injuries to the crop, with corresponding hit areas statistically calculated, thereby making it possible to sensings monitor the injuries and precisely determine areas hit by the varying-degree droughts.
Consecutive droughts that have occurred in the Canadian prairies have resulted in significant economic losses, ecological degradation, and environmental deterioration. The purpose of this study was to investigate the efficiency of remotely sensed data on drought assessment combined with climate data. The study area was the Canadian prairie ecozone in the provinces of Alberta, Saskatchewan, and Manitoba. There objectives were five-fold: 1) comparing Kriging and inverse distance weighting (IDW) interpolation methods, 2) comparing four spectral variables, the normalized difference vegetation index (NDVI), the enhanced vegetation index (EVI), the red and the mid infrared (MIR), 3) comparing three moisture indices (P-PET, P/PET and (P-PET/PET), 4) evaluating the relationships between spectral variables and moisture indices, and 5) assessing drought effects on different ecoregions. Results showed that there is no significant difference between Kriging and IDW, the two interpolation methods. MODIS vegetation indices could effectively assess drought conditions, especially EVI. Among the moisture indices compared, P-PET showed a better result. The impacts of droughts vary from year to year and from ecoregion to ecoregion. Aspen Parkland has higher drought resistance because of tree components.
Enhanced UV-B radiation due to stratospheric ozone depletion may have impacts on the productivity of agricultural crops. Which crop will be more sensitive to increased UV-B has received little attention. This paper presents a comparative study of the effects of supplemental UV-B on plant height, leaf area, biomass and yield among soybean, cotton, corn and wheat which were cultivated in fields in Nanjing, China. The experimental results showed that the four crops response to enhanced UV-B irradiation was shortened plant height, decreased leaf area and reduced biomass and yield of crops. Using the same criteria, the response of soybean and cotton to elevated UV-B is bigger than that of wheat and corn. RI (response index) is an integrated index which is the accumulation of relative change in plant
height, leaf area, biomass and yield, reflecting general impact of increased UV-B on crops. The results suggested that the RI for the four crops was minus, demonstrating a negative impact of enhanced UV-B on the crops. According to the RI, the soybean and cotton belong to
the sensitive plants category, wheat is a moderately sensitive plant and corn is a tolerant plant.
Ultraviolet radiation-B (UV-B) would increase due to the Ozone depletion. Global climatic factors, such as temperature, precipitation, evapotranspiration, soil moisture and CO2 content, are changing because of the increase of greenhouse emission and the destruction of ecosystems. Climate stress factors including enhanced UV-B irradiance have effects on crop production. Many studies have assessed the effects of enhanced UV-B on crops and impacts of global climatic change on crops separately. However, when UV-B effects were discussed, other environmental stress factors were generally neglected. It is well-known that crops in nature are seldom
affected by only a single stress factor, such as UV-B radiation. The impacts of enhanced UV-B radiation can be greatly increased or decreased by other environmental stress factors. In this paper, through field and plant growth chambers experiments, combined effects of enhanced UV-B radiation with other environmental stress factors
including solar visible light, temperature and soil moisture content on winter wheat were investigated. The experimental results showed that enhanced UV-B irradiance can restrain growth and development of winter wheat, which leads to reduction of plant height, leaf area, and slowing physiological activity and decreasing biomass and yield of winter wheat. The response of winter wheat to enhanced UV-B varied under different UV-B intensity and its combination with other environmental stress factors.
Based on the relationship between water balance and crop-water, water-saving irrigation model was integrated with monitoring and prediction of soil moisture, forming a system of decision-making of irrigation. It is demonstrated that straw mulching for winter wheat is an effective way to reduce soil evaporation at early stages and increase yield and improve water utilization efficiency. Combination of water-saving irrigation and straw mulching plays an important role in China water-saving agriculture.
KEYWORDS: Climatology, Climate change, Solar radiation models, Temperature metrology, Environmental sensing, Data modeling, Solar radiation, Geographic information systems, Agriculture, Raster graphics
Based on forty-one years observational data (1960-2000) from seventies weather stations, we analyze the characteristics of climate changes in winter growing season that is defined from November to April the next year. Supported by Geographical Information System (GIS) techniques, relative models are built between climate factors in winter growing season and heights above the sea level. In the context of recent decades climate conditions and assumed climate warming in the future, Climate Potential Productivity (CPP) for five winters crops are calculated, with making CPP distribution maps also. The features of climate changes in winter growing season in recent 41 years can be expressed as increases of mean temperature and precipitation and decrease of sunshine hours, the case appearing especially in 1990's. Temperature is a crucial factor in CPP model. Climate warming can improve the CPP. When the mean temperature increase 0.5°C, 1.0°C, 1.5°C and 2.0°C with unchangeable of other factors, the CPP will increase by 2.1%, 4.1%, 6.3%, and 8.3%. For the proportions of actual field per unit area to CPP for five winter crops are only 14% to 21%, it is beneficial to utilize winter climate resources rationally and increase crop's field.
Since the 1970's stratospheric zone attenuation liable for surface UV radiation enhancement has been among the ever-increasing concerns of global climatologists. In recent years, numerous efforts have been undertaken at home and abroad to investigate the effect of enhanced surface UV-B on crops' growth, development and yield formation, achieving a lot of significant fruits and concurrently on field ecosystems. As we know, most of the experiments in the past were conducted in laboratories, including a short-term response on an individual-plant basis. This condition differs consipicuously from yield experiments at the level of an ecosystem with regard to its long-range response. Specifically the degree to which the UV radiation influences non-crop species, which leads to the distortion of the response to UV-B enhancement of crop's population and its ecosystem. As a result, it is necessary to carry out long-range field experiments at an ecosystem's level. This paper aims at the impacts of intensified UV-B upon weeds and large soil worms (i.e., microanimals) in an ecosystem of growing wheat, corn (maize) and spinach together with preliminary investigation of the mechanisms.
Stratospheric ozone depletion and enhanced solar ultraviolet-B (UV-B) irradiance may have adverse impacts on the productivity of agricultural crops. Though only a small portion of the total solar electromagnetic spectrum, UV-B irradiance has a disproportionately large photobiological effect, largely because it is readily absorbed by important macromolecules such as proteins and nucleic acids. Numerous investigations have demonstrated that the effect of UV-B enhancements on plants includes a reduction in grain yield, alteration in species competition, susceptibility to disease, and changes in plant structure and pigmentation. Many experiments examining UV-B radiation effects on plants were conducted in growth chambers or greenhouses. It has been questioned if the effect of UV-B radiation on plants can be extrapolated to field responses from indoor studies because of the unnaturally high ratios of UV-B/UV-A and UV-B/PAR in many indoor studies. Field studies on UV-B radiation effect on plants have been recommended in order to use the UV and PAR irradiance provided by natural light. This study found the maize yield formation and yield structural elements responded to enhanced UV-B radiation under field conditions. Enhanced UV-B radiation caused a significant reduction of the dry matter accumulation and the maize grain yield in turn was affected. Analysis of yield structure indicates that the maize yield decreased with increased UV-B radiation and was evidently related to the decreased kernel weight and kernel number per ear.
The greater UV-B radiation has heightened concern that it has adverse impact on agricultural production and natural plant ecosystems. The effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species competition, decrease in photosynthetic activity, susceptibility to disease, and changes in plant structure and pigmentation. Plant responses to UV-B enhancements also include increased accumulation of flavoids, increased leaf thickness, increased reflectance of leaves, reductions in growth, and direct damage to photosynthetic mechanisms. One-third to one-half of all plant species tested are deleteriously affected by UV-B irradiance levels “above ambient.” This experiment was conducted to study responses of winter wheat growth and production under both ambient and sub-ambient UV-B irradiance (15.3% UV-B irradiance decrease from ambient level). Sub-ambient UV-B irradiance increased winter wheat growth and production, which indicates that current levels of ambient UV-B irradiance might have an adverse effect in tested areas.
Stratospheric ozone depletion has caused an increase in the amount of UV-B radiation reaching the earth’s surface. Numerous investigations have demonstrated that the effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species competition, susceptibility to disease, and changes in plant structure and pigmentation. Many experiments examining UV-B radiation effects on plants were conducted in growth chambers or greenhouses. It has been questioned if the effect of UV-B radiation on plants can be extrapolated to field responses from indoor studies because of the unnaturally high ratios of UV-B/UV-A and UV-B/PAR in many indoor studies. Field studies on UV-B radiation effect on plants has been recommended in order to use the UV and PAR irradiance provided by natural light. This study reported the growth and yield responses of a maize crop exposed to enhanced UV-B radiation and the UV-B effects on maize seed qualities under field conditions. Enhanced UV-B radiation caused a significant reduction of the dry matter accumulation, and the maize yield in turn was affected. With increased UV-B radiation the flavonoid accumulation in maize leaves increased, and the contents of chlorophyll a, b, and (a+b) of maize leaves were reduced. The levels of protein, sugar, and starch of maize seed decreased with enhanced UV-B radiation, while the level of lysine increased with enhanced UV-B radiation.
This article analyzed annual, seasonal and daily variations of total solar and ultraviolet (UV) radiation, based on observed data over Nanjing area from May 2001 to April 2002. The study shows that the daily variation of solar radiation and UV-radiation is bigger at noon, smaller in the morning and afternoon. When looking at it on an annual scale the variation is bigger in summer, smaller in winter. A linear regression equation has been set up to calculate quantities of UV-radiation that reaches the earth in a sunny day from daily-observed data.
A decrease in stratospheric ozone would lead to increases in Ultraviolet-B irradiances reaching the earth’s surface. The effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species competition, decrease in photosynthetic activity, susceptibility to disease, and changes in plant structure and pigmentation. A substantial number of studies have been conducted that have evaluated the potential consequences of an increase in UV-B radiation on many plants, but there are few studies that consider the changes of plant growth curve under increased UV-B radiation. This study evaluated availability of the four existing plant growth models under ambient level of UV-B radiation and supplemental UV-B radiation for soybean and winter wheat plants. Both of the Monomolecular and Divided simulation models proved not suitable for use in simulating plant growth under supplemental UV-B radiation. The Logistic model can be used to simulate plant growth in early growing stages and in the condition of Ck and T1 while the Gompertz model simulates plant growth better under T2 and T3 for soybean crop. For winter wheat crop, both of the Logistic and Gompertz models can be used to simulate plant growth under supplemental UV-B treatments.
The stratospheric ozone depletion and enhanced solar ultraviolet-B (UVB) irradiance may have adverse impacts on the productivity of agricultural crops. The effect of UVB enhancements on agricultural crops includes reduction in yield, alteration in species competition, decrease in photosynthetic activity, susceptibility to disease, and changes in structure and pigmentation. Many studies have examined the influence of supplementing UVB irradiance on different crops, but the effect of UVB irradiance on cotton crops has received little attention. The cotton crop is one of the most versatile of all the crops. It is a major fiber crop of the world and a major source of trade and economy in many countries. In this study we provide quantitative examination of the effects of elevated UVB irradiance on cotton. The tested cotton crop was grown under natural and supplemental levels of UVB irradiance in the cotton field. The results in this study showed that the supplemental UVB irradiance has negative impacts on cotton growth, development, yield, and fiber quality. A brief discussion is included on how the impacts on cotton contrast with impacts that have been observed in other studies on other plants, including trees.
Changes in ultraviolet (UV) radiation in Nanjing region were investigated in this study by using the simplified atmospheric radiation transfer computation model, the discrete-ordinate-method (DISORT) of radiation transfer, the climatic empirical model and observational method. The computational results of UV radiation were compared against observations showing that the computational values of UV radiation from the simplified model, and the DISORT and climatic methods were reasonable in agreement with observations.
The stratospheric ozone decrease has heightened concern over the ecological implications of increasing solar UVB radiation on agricultural production and natural plant ecosystems. UVB is absorbed and can damage many important plant species through a variety of interacting mechanisms. The effects of enhanced UVB exposure on yield and yield formation of winter wheat associated with photosynthetic activity and total biomass development were investigated in this study. The overall experimental design was three UVB treatments (two supplemental UVB treatments and an ambient level) and three replicates of each treatment. The results suggested that the supplemental UVB can cause the decrease of yield of winter wheat up to 24% with 11.4% increased UVB. The key growing stage which cause the yield decrease is during the jointing-spike formation. This study also investigated the effects of supplemental UVB on production of dry matter, allocation, LAI, total biomass, and photosynthetic activity of winter wheat. The combined UVB effect with other environmental stress factors on wheat was discussed in this study.
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