Soil-Vegetation-Atmosphere Radiative Transfer Model in Microwave Region

The radiative transfer is one of the significant theories that describe the processes of scattering, emission, and absorption of electromagnetic radiant intensity through scattering medium. It is the basis of the study on the quan-titative remote sensing. In this paper, the radiative characteristics of soil, vegetation, and atmosphere were described respectively. The numerical solution of radiative transfer was accomplished by Successive Orders of Scattering (SOS). A radiative transfer model for simulating microwave brightness temperature over land surfaces was constructed, de-signed, and implemented. Analyzing the database generated from soil-vegetation-atmosphere radiative transfer model under Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) configuration showed that the atmospheric effects on microwave brightness temperature should not be neglected, particularly for higher frequency, and can be parameterized. At the same time, the relationship between the emissivities of the different channels was developed. The study results will promote the development of algorithm to retrieve geophysical parameters from mi-crowave remotely sensed data.

Soil-vegetation-atmosphere interaction over a hilly forest in the southern Huaihe River Basin:Long-term field experiment and preliminary analysis of basic observations

To improve the understanding of the CO_(2) exchange and the cycling of energy and water between the land surface and atmosphere over a typical hilly forest in southeastern China,a long-term field experimental observatory was established in Huainan,Anhui Province.Here,the authors briefly describe the three parts of ongoing research activities:the environmental monitoring at the site,the meteorological observations on a high tower,and particularly the intensive measurement of soil-vegetation-atmosphere interaction on a lower tower.Specifically,the diurnal variation of basic meteorological variables on a typical clear day(13 July 2018),and their temporal variation in the first three months of the low tower’s operation(4 June to 31 August 2018),and in combination with simultaneous data from the high tower,are analyzed.Results show that the data demonstrate reasonable variabilities,and the variables exhibit significant diurnal variation,characteristics of summer values,and considerable differences in summer months.The daily and monthly average albedos above the forest canopy were both 0.13.The daily average soil CO_(2) concentration was 1726 and 4481 ppm at 2 and 10 cm,respectively.The soil CO_(2) concentration changed with soil volumetric moisture contents,but showed a weak correlation with soil temperature in summer 2018.As the observatory continues to run and data continue to be collated,further investigation of the long-term variation of monsoon characteristics should be performed in the future.The experiment is useful in ecosystem and atmosphere interaction research,as well as for the development and evaluation of climate models,in the transitional climate zone of the Huaihe River basin.

Simulation of energy and water balance in Soil-Vegetation-Atmosphere Transfer system in the mountain area of Heihe River Basin at Hexi Corridor of northwest China

In the mountain area of inland Heihe River Basin at Hexi Corridor of northwest China during the vegetation growing season from May to September, the Simultaneous Heat and Water (SHAW) model of Soil-Vegetation-Atmosphere Transfer (SVAT) system is applied to simulating and studying energy and water balance of the soil-residue-plant canopy layers in the Picea crassifolia forest and the grassland by the forest at the shaded slope and the grassland at the sun-facing slope. The simulation of energy balance indicates that net radiation of the grass- land at the sun-facing slope is more than that of the Picea crassifolia forest and the grassland by the forest at the shaded slope. The energy outgoing components are the first latent heat and next sensible heat from the grassland both at the shaded slope and the sun-facing slope, but those at the former are less. The energy outgoing components are the first sensible heat and next latent heat from the Picea crassifolia forest. The composition and distribution of energy in the soil-residue-plant canopy layers in the Picea crassifolia forest and the grassland by the forest at the shaded slope make the soil layer receive less energy, which therefore, especially the forest possesses the energy conditions for soil water conservation. The simulation of water balance indicates that the water loss of the grassland at the sun-facing slope is mainly caused by soil evaporation, while evapotranspiration of the Picea crassifolia forest and the grassland by the forest at the shaded slope is less than that of the grassland at the sun-facing slope. Half of the evapotranspiration of the Picea crassifolia forest and the grassland by the forest at the shaded slope is consumed by transpiration. After precipitation, the soil water storage is increased much more for the Picea crassifolia forest and also more for the grassland by the forest at the shaded slope. Therefore the shaded slope vegetation, especially the forest is favorable for soil water storage.