Inverse The Phenology Of Rice Spatial And Temporal Variations Based On MODIS Data In Northeast China

Information of crop phenology can directly retrieval the effect of temperature andprecipitation to the crop, which is essential for evaluating crop growth, productivity and cropmanagement. Remote sensing technique is an important method to detect vegetation phenologywith high spatial–temporal scales.First we developed a method for determining phenologicalstages of rice based on EOS-MODIS multi-temporal remotely sensing data of2008. In thispaper, rice crop phenological stages was detected by using EOS-MODIS data, the24observedsites for rice phenological stages were selected in the Northeast China. The filtering time-seriesEnhanced Vegetation Index (EVI) data by wavelet transforms from MODIS/Terra data wereperformed. The planting date, heading date and ripening period were detected by the variationcharacteristics in smoothed EVI time profile in2008. The twenty six types of wavelet:Daubechies(7-20)， Coiflet(3-5) and Symlet(7-15) were used. Through comparing ricephenological stages of24agrometeorological observed sites data in study area in2008, andcalculating root mean square errors. The results show that, the case using Symlet11showed aremarkably good result in determining phenological stages and growing periods, which iscompared with the observation data. Most of the root mean square errors in planting date wereless than16days. Most of the root mean square errors in heading date and ripening period wereless than8days.The methods presented in this study could be applied to generate the growth stages andphenology of rice in the Northeast China. We can get the spatial distribution map and the timevariation of rice phenology in the period2000-2010for the entire northeast region. The resultsshow that:(1) Throughout the Northeast to11-year average rice phenology distribution, thetransplanting date is mainly concentrated in the130to140days (mid May), heading date mainlyconcentrated in the210to220days (early August), the ripening date is mainly concentrated inthe250to260days (mid-September) growing season length of120to130days. Transplantingdate shows characteristics the South as early as late North, first appeared in northern Liaoningand Jilin central region of120-130days (early May); most of the latest distribution is in thesouthern region of Heilongjiang, in the150-160days (early June). Heading date also presents theSouth as early as late North. Heading first appeared in northern Liaoning and Jilin central regionin200-210days (late July) and the latest mainly distributed in Heilongjiang in the Northeast in 220-230days (mid-August). On the contrary, ripening date showing the North as early as thecharacteristics of the Southern night, first appeared in the central region of Heilongjiang, in240-250days (early September), the latest in central Jilin and Liaoning in northern parts of the260-270days (late September). Length of growing season showing the north short and theSouth long, the shortest length of the growing season emergens in the central region ofHeilongjiang,90-100days. longer length of growing season appears in northern Liaoning andJilin Central,130-140days. North and South difference is about30days.(2) Transplanting dateof Liaohe River Plain region, northern Jilin and Heilongjiang in the southern region havepostponed. Ahead of trends appeared in Liaoning in northern, central and southern Jilin andHeilongjiang in northern. Heading date ahead of trends emergened in the Liaohe River Plain andthe Sanjiang Plain, postpone the trend in central Jilin Province and Heilongjiang in most parts ofsouthern. Ripening date have the delay trend in the northeast central region and in northeasternHeilongjiang and eastern part of Jilin have the the advance trend. Liaohe River Plain regionshowing a more complex situation, postpone the trends and ahead of trends both exist. Thelength of the growing season is more obvious decrease in central Jilin Province and growth trendemergened in the southeast of Heilongjiang and Liaohe region in southern. Other places bothexists the trends of decrease and increase.(3) Our analysis based on site observation and remotesensing data to extract phenological information as rice transplanting, heading date, ripening andgrowing season length at four sites which are Wuchang, Xinbin, Jian, Dawa from2000to2010.Between the two ways the trends in the transplanting data and heading data fit better. Ripeningdata in Wuchang and Jian station have some difference. The overall effect is still acceptablephenological information based on remote sensing data extraction.