Based on the relationship between yield of winter wheat at different growth stages and meteorological factors, the actual
yield can be segregated step by step. Based on the yield data of reviving period to heading date without meteorological
disasters, the ideal yield were calculated with Lagrange's Interpolation Polynomial and the yield loss rate affected by
meteorological disasters have been assessed. By analyzing the degree of different meteorological disasters and their
effect on yield from turning green period to heading date, the model of evaluation on late frost loss was defined. Take
Shangqiu station as representative in Huanghuai Area, the yield loss caused by frost from 1980 to 2006 were simulated
and analyzed. The results shows that the average rate of yield loss was 11.7% and the heavy disaster years of yield loss
can be above 30%.
Retrieving land-surface temperature with split-window algorithm was firstly applied to NOAA-AVHRR data.
With the application of MODIS sensor, its data has been used more and more widely. Since MODIS sensor is able
to observe vapor in the air, it can provide the parameters including vapor content and atmospheric transmissivity
for split-window algorithm which can thus be applied more conveniently. The article, adopting the split-window
algorithms of Becker-Li (1990), Sobrino (1991) and Qin Zhihao (2005), retrieves the surface temperature at
daytime and nighttime with MODIS1B data and compares with the surface temperature products of NASA. Finally,
the algorithm of Qin Zhihao is demonstrated to be the one with higher accuracy at daytime and nighttime and the
algorithm for surface temperature at nighttime is simple with acceptable accuracy.
The growth of crops is directly related to solar radiation whose variances influence the
photosynthesis of crops and the growth momentum thereof. This dissertation has Zhengzhou, which
located in the Huanghuai Farmland Ecological System of China, as an example to analyze the rules of
variances of total solar radiation, direct radiation and diffusive radiation. With the help of linear trend
fitting, it is identified that total radiation (TR) drops as a whole at a rate of 1.6482J/m2. Such drop has
been particularly apparent in recent years with a period of 7 to 16 years; diffusive radiation (DF) tends
to increase at a rate of 15.149 J/m2 with a period of 20 years; direct radiation (DR) tends to drop at a
rate of 15.843 J/m2 without apparent period. The total radiation has been on the decrease ever since
1980 during the growth period of wheat. Having modified relevant Parameter in the Carbon and
Nitrogen Biogeochemistry in Agroecosystems Model (DNDC) model and simulated the influence of
solar radiation variances on the development phase, leaf area index (LAI), grain weight, etc during the
growth period of wheat, it is found that solar radiation is in positive proportion to LAI and grain weight
(GRNWT) but not apparently related to development phase (DP). The change of total radiation delays
the maximization of wheat LAI, reduces wheat LAI before winter but has no apparent effect in winter
and decreases wheat LAI from jointing period to filling period; it has no apparent influence on grain
formation at the early stage of grain formation, slows down the weight increase of grains during the
filling period and accelerates the weight increase of grains at the end of filling period. Variance of
radiations does not affect the DP of wheat much.
Based on 1982-1999 satellite sensings, meteorological data and observations of crop growth/development, a study is conducted on seasonal and interannual variations in vegetation NDVI (normalized difference vegetation index), its response to climate change and its relationship with crop growth/development during the period in Zhengzhou region of Henan province. Evidence suggests that the interannual change is not so pronounced in the regional NDVI, exhibiting, on the whole, an unsteadily increasing trend; stronger seasonality is shown in the annual variation, with a more significant rising trend in spring as opposed to those for summer and autumn; NDVI change is in positive correlation both to temperature and precipitation (stronger response to temperature), with its change subject dominantly to temperature and rainfall in spring and summer, respectively, under varying effect of temperature and precipitation in autumn, and largely under the impacts of heat in winter and during the growth of winter wheat and summer-sown corn the NDVI is positively correlated to the crop height and density (the number of crop individuals per unit area) in their milking stage, the latter acting as a principal factor of NDVI change.
Using Landsat TM and ETM+ images in 1993 and 2004 to interpret the variation of land use and vegetation cover in Zhengzhou area, a study is conducted on the current situation and change of desertification and vegetation cover during 1993-2004, indicating that the desertification has been under control, leading to the decline of the area and most of the waste land converted into arable land, but nevertheless vegetative coverage has dropped by 0.43% in this study period, and especially the woodland has greatly decreased, responsible for lowered vegetation area and vulnerable ecological environment. Some countermeasures are proposed against desertification and for expanding vegetation coverage in an effort to form a good ecosystem in the research area.
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.
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.
In the context of daily rainfall from 58 stations in South China and day-to-day gridded reanalysis from NCEP/NCAR, study is performed of April-June precipitation features at different time intervals in the research area in relation to the establishment of summer monsoon in the South-China Sea (SCS). Results show that the rainfall consists of frontal and monsoon rainfall, the former occurring dominantly in April and the latter largely in June as its principal phase, indicating that the vapor transport, dynamic and thermal features vary greatly for both. Further analysis shows that the amount of the frontal precipitation bears an intimate relation to the time of monsoon onset. In the year of deficient frontal rainfall the Sri Lanka vortex appears earlier and spreads northwards, in combination with northward-advancing convective band from Sumatra to cause the Indo-Burma trough to be established, as well as the subtropical high-pressure belt to break and eastward retreat - all happen earlier than usual, a situation that favors the establishment of westerlies in the SCS, leading to earlier establishment of SCS summer monsoon. In years of plentiful frontal rainfall, however, the formation of the Bengal Bay trough depends mainly on the displacement of Sumatra convection into the Indo-China peninsula, a situation unfavorable for the earlier breaking of the subtropical high-pressure belt and its eastward movement, resulting in later establishment of west winds in the SCS, so that SCS summer monsoon has its establishment delayed.
Using data from Zhengzhou the Excel-made time-dependent variations in the growth and development (G/D) stages of winter wheat in 1981-2002 are investigated, with analysis done of the curves. Also, the trends of G/D variations over the years are dealt with by use of the related tendency rates of the appearing dates of all the G/D stages of the crop. Results show that the dates of pre-winter G/D stages depend mainly on the seeding date and the overwhelming majority of the G/D stages shift to an earlier date in the vegetative growth period. A statistical expression is constructed by utilizing the 1981-2002 data of the number of days of the G/D stages and corresponding mean temperatures, with which to explain the variation of the G/D stages of winter wheat.
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.