Abstract
A long-term investigation of the attenuation in non-rainy conditions has been carried out, for a tropical and a temperate location, using meteorological data and NWP (Numerical Weather Prediction) products during the period 2011-2015. The results show that ERA-5 full profiles are appropriate to estimate non-rainy attenuation in lieu of radiometric or radiosonde observations. Simpler regression-based methods are established. A new formulation for oxygen attenuation is introduced, which only requires surface temperature and pressure. Mass absorption coefficients are used for water vapour and cloud attenuation. Simpler regression-based approaches are then validated. The non-rainy attenuation at K, Ka and Q bands has been found noticeably higher in the tropics than in the temperate region. This study would facilitate the planning of global mobile satellite communication systems.
Highlights
The ever-increasing demand for higher data rates to support satellite services has led to a migration of communications to higher bands, namely from 11 to 50 GHz
The results show that Radiometer, Radiosonde observations (RAOBS), and ERA-5 data, in combination, have produced useful statistics of cloud attenuation occurrences that validate the regression model (3), and are useful for evaluating satellite link budget at the three frequency bands considered
It should be noted that an abrupt increase in the attenuation value is observed at Kolkata for exceedance probability less than 20%, which is due to a significant increase in the cloud attenuation during Indian Summer Monsoon (ISM), as evident from the time series plot of Fig. 11 (b)-(d) caused by high cloud cover, while LLN does not experience such high cloud attenuation during a particular season [21]
Summary
The ever-increasing demand for higher data rates to support satellite services has led to a migration of communications to higher bands, namely from 11 to 50 GHz. In the higher frequency bands, the signal is significantly impaired by atmospheric constituents like gases, clouds, rain, and tropospheric turbulence, affecting the link reliability and system performance [1]–[3]. Studies on rain attenuation in tropical and temperate regions at various frequency bands facilitated the selection of suitable Fade Mitigation Technique to increase data rates and link availabilities [3], [6]–[8]. There were comparatively fewer studies focusing on the attenuation in non-rainy conditions, even though the degradation due to gases and clouds increases in Q/V band at lower elevation angle
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