Atmospheric Profiling in the Inter-Tropical Ocean Area Based on Neural Network Approach Using GPS Radio Occultations
نویسندگان
چکیده
In this study we have proposed a method based on neural networks to retrieve refractivity, temperature, pressure and humidity profiles by using FORMOSAT-3/COSMIC GPS radio occultation data. To overcome the constraint of an independent knowledge of one atmospheric parameter at each GPS occultation, we trained three neural networks with refractivity profiles as input computed from the geometrical occultation parameters relative to the FORMOSAT3/COSMIC satellites, while the targets were the dry and wet refractivity profiles and the dry pressure profiles obtained from the contemporary European Centre for Medium-Range Weather Forecast data. We have considered 1041 available satellite radio occultations covering the entire ocean area spanning within the Tropics during July-August 2006. We have used 937 profiles for training the neural networks, the remaining 104 ones for the independent test.
منابع مشابه
Comparison of Different Neural Network Approaches for the Tropospheric Profiling over the Inter-tropical lands Using GPS Radio Occultation Data
In this study different approaches based on multilayer perceptron neural networks are proposed and evaluated with the aim to retrieve tropospheric profiles by using GPS radio occultation data. We employed a data set of 445 occultations covering the land surface within the Tropics, split into desert and vegetation zone. The neural networks were trained with refractivity profiles as input compute...
متن کاملCosmic Gps Radio Occultation: Neural Networks for Tropospheric Profiling over the Intertropical Ocean Area
Global Positioning System (GPS) radio-occultation (RO) is provided as a global sounding technique for obtaining atmospheric profiles by integrating them in global models for numerical weather prediction and for climate change studies. The radio occultation system employs GPS receivers placed on a Low-Earth Orbit (LEO) satellite to sound the Earth’s troposphere and ionosphere evaluating the addi...
متن کاملValidation of Water Vapour Profiles from GPS Radio Occultations in the Arctic
The relevance of water vapour in atmospheric physics and climate research contrasts strongly with the availability of humidity data in the Arctic. The most extensive humidity data set is based on approx. 80 radiosonde stations north of 60°N, but suffers from two major problems: Sensor diversity and sensor limitations under Arctic conditions, on the one hand, and lacking radiosonde launch sites ...
متن کاملGRAS – Metop’s GPS-Based Atmospheric Sounder
Introduction Occultation methods based on effects connected with the refraction of electromagnetic waves in both the optical and radiofrequency domains have been used by astronomers for numerous investigations of planetary atmospheres over the last decades. The first experiment started with the Mars flyby by Mariner-IV in 1964. Since this first attempt, radio-occultation experiments have been c...
متن کاملEstimation of tropospheric profiles using COSMIC GPS radio occultation data with neural networks
In this work we have proposed a method based on neural networks to directly retrieve dry and wet refractivity and dry pressure profiles in troposphere (which in turn can be used to obtain temperature and humidity profiles) by using COSMIC GPS radio occultation (RO) data. To overcome the constraint of an independent knowledge of one atmospheric parameter at each GPS occultation, we trained diffe...
متن کامل