Effect of Saline Soil Cracks on Satellite Spectral Inversion Electrical Conductivity

The dehydration cracking of saline soil is a kind of common natural phenomenon, and the cracks of saline soil will affect the satellite spectrum, and then affect the accuracy of satellite spectral inversion of electrical conductivity (EC). This study introduces the concept of crack rate (CR) to describe the crack information of saline soil, and quantifies the influence of saline soil crack on the EC of satellite spectral inversion. In 2014 and 2020, the satellite-ground synchronous observation experiments of soda-type inland saline soil and coastal chlorinated-type saline soil were carried out, and the CR of surface cracked saline soil was extracted by an image processing algorithm. For the saline soil spectrum data, the correlation analysis method is used to establish the best band combination that characterizes the relationship between the different saline soil spectrum data and salinity, and the EC inversion model is established using the BP neural network method. The results show that: after the CR is introduced, the determination coefficient (R2) for the EC of soda-type saline soil satellite spectral inversion increased from 0.59 to 0.67, with an increase of 14.42%, and the mean square error (MSE) reduced from 0.20 to 0.16, with a decrease of 19.49%. The R2 for the EC of coastal chlorinated-type saline soil satellite spectral inversion increased from 0.64 to 0.75, an increase of 17.73%, and the MSE decreased from 0.16 to 0.12, a decrease of 25.15%. The study proved the influence of the cracks in the saline soil on the satellite spectrum and provided a new way to improve the accuracy of the satellite spectrum inversion of the EC of the cracked saline soil.

Rain attenuation in broadband satellite service and worst month analysis

<span>Satellite link design, link margin and services at lower bands of satellite spectrum has been facing the challenges of meeting the demands for higher bandwidth requirements. Satellite operators and service providers are been compelled to migrate to the use of higher frequencies above 10 GHz. These higher frequencies were discovered to be vulnerable to atmospheric degradation creating the challenge of service availability especially for tropical rain zones with higher rainfall intensities and longer rain event durations. This study strive to evaluate the profile of rainfall and the monthly and annual variability to improve the design parameters of satellite propagation. Two yeas rainfall measurement campaign was conducted in Abuja at Nigcomsat-1R ground station with a view to understanding the characteristics of Abuja rain. The location of the site is on lat. 9.06o N and lon. 7.48o E. Tipping bucket rain gauge was used for point rain rate and 1.8 m VSAT antenna was installed to monitor the rain induced attenuation on satellite broadband signal. The results shows a huge variability between month to month as well as annual average between 2016 and 2017. The performance of broadband satellite service was found to largely to depend on the quality of the carrier power above the system noise rather than bandwidth capacity or the receive signal level while higher attenuations are associated with higher rain intensities and the slant path effects.</span>