Salinization Monitoring And Soil Moisture And Salinity Retrieval Based On Optical And Microwave Remote Sensing Technology

Soil moisture has a very important impact on the earth's water cycle,energy cycle,ecological environment and agricultural production.Soil is an important boundary between the land surface and the atmosphere,and it is also a key medium for surface evapotranspiration.Soil moisture and soil salinity are also two important indicators for judging soil health and the risk of land salinization.Especially in arid and semi-arid regions,soil salinization is inextricably linked to long-term soil water loss and soil salinity.Therefore,accurate retrieval of various parameters such as soil moisture and soil salinity and monitoring of land environmental degradation such as land salinization are of great significance.For a long time,human beings have maintained close research on soil moisture salinity parameters and soil salinization.The traditional monitoring methods are mostly individual site data,collecting measured soil samples and so on.This requires a lot of human and material investment,and is constrained by the measurement method,and observation scale,real-time,effectiveness,reliability and representativeness and other aspects problems are difficult to overcome.In recent decades,through satellite remote sensing technology to achieve ground observation,parameter inversion and other aspects of research and development,a number of countries and organizations around the world have launched a number of various spectral segments,resolutions and time series of ground observation satellites.These satellites have been used in practical applications such as soil moisture monitoring,disaster prevention,urban planning,intelligent transportation,mineral and resource surveys,eco-environmental monitoring,and climate change assessment.Among them,optical remote sensing image has the characteristics of rich spectral band information,good imaging quality and high resolution,good noise resistance and high signal-to-noise ratio in the absence of large area cloud interference.Besides,optical remote sensing image has intuitive spectral data observation,rich spatial information,and the processing of remote sensing data is highly intersecting with the traditional concept of image processing.Optical remote sensing images have unique advantages and good applications in the classification and identification of features,especially in the monitoring of vegetation chlorophyll and soil salinization.Compared with optical remote sensing,microwave remote sensing has longer wavelengths,strong penetrating force for atmosphere and clouds,and is not easily affected by weather conditions.Therefore,it can achieve global monitoring of large-scale ground observation.Meanwhile,microwave can penetrate the surface soil surface,and the temperature and dielectric characteristics of the medium is very sensitive,it can be widely used in surface soil moisture and temperature inversion.Therefore,the research on the complex imaging mechanism of remote sensing technology,the development of related algorithms,the calibration and evaluation of existing data and products have very realistic significance and urgent needs for Earth science,such as geophysics,hydrology,energy and water cycle,as well as the global ecological environment,regional economic development,human agricultural life and so on.Based on satellite remote sensing data,the physical basis,observation geometry,radiation transmission process,energy exchange and other imaging mechanisms of optical remote sensing,this paper studied in the direction of remote sensing geographic information technology,remote sensing physical process,remote sensing data processing and physical properties of observation objects.Meanwhile,the image processing methods of remote sensing data,such as pattern recognition classification,spatial scale conversion,image enhancement and stretching,are studied in detail.On this basis,the spectral properties and salinity grades of salinized soils were studied by using medium and high spatial resolution multispectral data,and the content of water-soluble salinity in soil moisture and soil was analyzed by passive microwave data,and the evaluation of soil moisture products and the analysis of influencing factors were constructed by using the cell scale ground observation network.The main specific work of this paper is as follows:(1)Based on the multispectral data from MODIS(Moderate Resolution Imaging Spectroradiometer)sensor,LANDSAT 7 satellite ETM+(Enhanced thematic Mapper)and the Landsat 8 satellite OLI(Operational Land Imager)sensor,this paper analyzed the optical remote sensing spectral characteristics and performance characteristics of the salinized soil in the typical saline soil experimental area of western Jilin Province experimentally.Besides,this paper calculated the soil salinization index of satellite data and compared with the measured soil EC value and soil salinity.By comparing MODIS data and LANDSAT data with spatial scale consistency transformation to discuss the influence of spectral resolution and spatial resolution on soil salinization monitoring was discussed.The influence of data with narrow spectral band width and low spatial resolution on the proportion of the accuracy of the observed results is studied with the width of the spectrum with wide bandwidth and high spatial resolution.(2)The microwave dielectric characteristics of soil with different component types under soil moisture content were analyzed based on passive microwave brightness temperature data.Considering the influence of soil water-soluble salinity factors on soil dielectric constant,the Dobson soil dielectric constant model with saline dielectric constant model was constructed.And the soil moisture salinity parameters in the inversion experiment area were calculated iteratively by constructing the cost function.Taking the western part of Jilin Province as the research area,the spatial distribution of soil moisture salinity was analyzed and studied according to the inversion results combined with meteorological site data and measured soil data in the space range.(3)A measured soil moisture observation network for the agricultural tillage surface of microwave soil moisture product scale was constructed.The main work including the location selection of network construction,sensor testing and calibration process,as well as the field laying process of sensor probes.The experimental standards are based on the spatial scale and penetration depth of satellite microwave soil moisture products.(4)The Thiessen Polygons method was used to transform the multi-observation point data of ground observation network with the scale matching of microwave cells.The measured soil moisture data of the observation network were applied to the AMSR2/JAXA soil moisture products and AMSR2/based on the passive microwave X-band.Accurate evaluation of soil moisture products and FY3B/MWRI soil moisture products in LPRM.The properties and influencing factors of soil moisture products in the harvest cycle of complete agricultural cultivation were studied by surface temperature,vegetation cover and actual soil moisture.The research content of this paper focuses on remote sensing physics and application,involving multi-domain disciplines,covering multi-source and multi-category remote sensing data.This paper put forward specific methods and algorithms for soil salinization monitoring and soil moisture salinity parameter inversion.By constructing ground soil moisture observation network to verify the soil moisture products in the complete cultivation cycle,to analyze the soil changes and product performance.To a certain extent,it has certain guiding significance to the research and development of the subsequent related method algorithm,such as the developing,strategy making and the ground Verification experiment construction scheme.