The orchards are developing very fast in the northern China in recent years with the increasing demands on fruits in
China. In most parts of the northern China, the risk of frost damage to fruit tree in early spring is potentially high under the background of global warming. The growing season comes earlier than it does in normal year due to the warm weather in earlier spring and the risk will be higher in this case. According to the reports, frost event in spring happens almost every year in Ningxia Region, China. In bad cases, late frosts in spring can be devastating all fruit. So lots of attention has been given to the study in monitoring, evaluating, preventing and mitigating frost. Two orchards in Ningxia, Taole and Jiaozishan orchards were selected as the study areas. MODIS data were used to monitor frost events in combination with minimum air temperature recorded at weather station. The paper presents the findings. The very good correlation was found between MODIS LST and minimum air temperature in Ningxia. Light, middle and severe frosts were captured in the study area by MODIS LST. The MODIS LST shows the spatial differences of temperature in the orchards. 10 frost events in April from 2000 to 2010 were captured by the satellite data. The monitoring information may be hours ahead circulated to the fruit farmers to prevent the damage and loss of fruit trees.
The vegetation’s variation is very sensitive to climatic change and Human activates in Northwestern China. The vegetation distribution in Northwest of China since 1981 to 2003 is assessed with Normalized Difference Vegetation Index (NDVI) data. The vegetation season change is in accord with change of surface energy. And most of vegetation in Northwest China is related to rainfall. The value of drought index is in accord with the change of NDVI in Northwest China. More rainfall in spring or summer resulted in the increase of NDVI values in Shanxi, Inner Mongolia, Gansu, Ningxia, and Qinghai. But the NDVI in arid region, such as Xinjiang, has been little influenced by rainfall. The conclusion is that precipitation, melted snow or ice water, and irrigation are all the factors affecting vegetation growth.
Solar irradiation is a way to characterize the climate of particular region, and used in tourism and agriculture. The Heliosat-Ⅱ method of deriving solar irradiation from FY-2C geostationary satellite images was evaluated for China. The results clear show that the Heliosat-Ⅱ method is feasible to mapping surface solar irradiation over China using FY-2 images, especially for the regions where the measured solar irradiation is not available.
Drought occurs everywhere in the world and is one of the costliest natural hazards. The Group on Earth Observations
(GEO) has advocated implementing a Global Drought Early Warning System (GDEWS) since 2007. Various indices
have been developed and used to depict drought. According to the survey, various drought monitoring system with
remote sensing at regional, national or local level are existing, but the integration with the drought system based on the weather station data, in particular at the global level is still weak. However, the GEO Global Agricultural Monitoring Initiative was recognized by the G20 agricultural ministers and will enhance the linkage between GEO-GLAM and GDEWS. The capability for a component of drought monitoring with remote sensing is there in place. MODIS data have been used to globally track the distribution of crop failures due to droughts. In China, the Chinese meteorological satellite, FY is also ready to monitoring drought globally. MERSI onboard FY-3 is similar with MODIS and helpful to monitor the occurrence, development of drought at different scales. JRC MARS issues periodical bulletin on agricultural conditions. Agricultural Division of Statistics, Canada issues weekly crop condition reports. In India, the biweekly drought bulletin and monthly reports is issued under National Agricultural Drought Assessment and Monitoring System (NADAMS). Similar program is followed in many countries world-wide. The informed information of drought is helpful for governmental officials and formers to in advance prepare for coping with the likely coming drought. The global efforts should be in place to promote the global drought information system with a remote sensing drought component.
AVHRR NDVI time-series datasets were used to investigate the variations in the key phenology events
in cropland of North China over the past 20 years. The method based on Savizky-Golay filter was used
to reconstruct NDVI time-series data set, and reduce the effects time-series of cloud contamination and
the Bidirectional Reflectance Distribution Function (BRDF). Based on NOAA / AVHRR NDVI 10-day
time-series data, we estimated that the growing season duration of summer maturing crop has
lengthened, primarily through an earlier onset date of the start of the growing season (SGS) and a later
onset date of the end of the growing season (EGS) during period of 1982-2000 in north China. The
autumn maturing crop has not showed the seminar characterization in area with double crop system.
The onset date of SGS is earlier, and the onset date of EGS has slightly delayed in area with one crop system.
Sunshine duration is a way to characterize the climate of particular region, and used in tourism and
agriculture. The method of retrieved sunshine duration from satellite derived cloud index was evaluated
for north China by FY-2C visible images, measured data. The results clear show that the FY-2C data
can be used for mapping sunshine duration over north China. The FY-2C data is useful for sunshine
duration retrieval for where the sunshine duration is not available.
Information of crop phenological stages is essential for evaluating crop productivity and crop management. We used
MODIS EVI time-series to monitoring winter-wheat phenology in North China. The phenological estimations from
MODIS EVI measurements were compared with situ data. Results indicate that winter-wheat phenological stages
derived from MODIS EVI time series data is feasible. The spatial pattern of winter-wheat shows obvious latitudinal
trends in this region. Green up, tassel, and maturity onset dates in more southern zone begin earlier progressively than
the northern zone.
In the present study, a detailed analysis of AVHRR-based Vegetation Health Indices and meteorological data of
Huanghuai region has been carried out for the years 1981-2008. Detailed analyses of spatial and temporal drought
dynamics have been carried out. The results revealed that the low-grade of droughts are common phenomena in north
China's main agricultural area. Moreover, the area coverage of droughts in different seasons and different regions
displayed different trends. There is a decrease tendency for soil moisture in recent years.
In this study, the temperature vegetation dryness index (TVDI) which derived from NOAA/AVHRR data was
applied to monitor the severe drought in Sichuan Basin in the summer of 2006. The result using TVDI shown : the
drought developed rapidly in the last ten days of July, and became most severe at the end of August, then alleviated in
the first ten days of September. The change trends of TVDI with low rainfall and high air temperature were basically
consistent. The sensitivity of TVDI to air temperature and principle was also analyzed. TVDI had positive correlation
with temperature, negative correlation with precipitation. TVDI is an effective method for the monitoring of the regional