Search

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/m 2 . 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/m 2 with a period of 20 years; direct radiation (DR) tends to drop at a rate of 15.843 J/m 2 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.

The aerosol number concentration data in 31 various bands, which was observed by the apparatus Grimm 180 at Zhengzhou Atmospheric Constituents Station (ZACS) from the beginning of January to the middle of July in 2006, has been classified into 3 typical scales according to 3 different volume concentration peak values each one representing the various sources of aerosols to analyze their temporal variation periods by the morlet-wave method. In addition, seeing the volume concentrations of the various typical scales of aerosols as controlling factors and using the time-serials of them, the dynamics equations of the composed system of various sources of aerosols have been established to explain the volume concentration's varies with the meteorological factors in the Middle China.

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.

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.

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.