Study of the Spatiotemporal Characteristics of the Equatorial Ionization Anomaly Using Shipborne Multi-GNSS Data: A Case Analysis (120–150°E, Western Pacific Ocean, 2014–2015)

Xiaowen Luo,Xiaoming Qin,Di Wang,Jinyao Gao,Tao Zhang,Jinling Wang,Ziyin Wu,Chunguo Yang,Xiaolun Chen

doi:10.3390/rs13153051

Abstract

Ground-based GNSS (Global Navigation Satellite System) reference stations lack the capacity to provide data for ocean regions with sufficient spatial-temporal resolution, limiting the detailed study of the equatorial ionization anomaly (EIA). Thus, this study collected kinematic multi-GNSS data on the ionospheric Total Electron Content (TEC) during two research cruises across the equator in the Western Pacific Ocean in 2014 (31 October–8 November) and 2015 (29 March–6 April). The purpose of the study was to use sufficient spatial–temporal resolution data to conduct a detailed analysis of the diurnal variation of the equatorial ionization anomaly in different seasons. The two-year data collected were used to draw the following conclusions. During the test in 2014, the EIA phenomenon in the Northern and Southern Hemispheres was relatively obvious. The maximum values occurred at local time (LT) 15:00 (~136TECu) and LT22:00 (~107TECu) in the Northern Hemisphere and at LT14:00 (100TECu) and LT22:00 (80TECu) in the Southern Hemisphere. During the test in 2015, the EIA in the Southern Hemisphere reached its maximum level at LT14:00 (~115TECu) and LT20:00 (~85TECu). However, the EIA phenomenon in the Northern Hemisphere was weakened, and a maximum value occurred only at LT 15:00 (~85TECu). The intensity contrast was reversed. The EIA phenomenon manifests a strong hemisphere asymmetry in this region.

Highlights

Equatorial Ionization Anomaly (EIA), as a unique ionospheric structure, was proposed and explained by Appleton in 1946 [1]
The above advantages are the prerequisite for applying GNSS technology to the research of EIA phenomenon
The resemblance in shape and magnitude between the ionospheric Total Electron Content (TEC) when the location of the ship and an International GNSS Service (IGS) station were in proximity ionospheric TECs when the location of the ship and an IGS station were in proximity proved the reliability of the kinematic ionospheric TEC data

Summary

Introduction

Equatorial Ionization Anomaly (EIA), as a unique ionospheric structure, was proposed and explained by Appleton in 1946 [1]. Many scholars around the world have since observed and studied this phenomenon for decades [2,3,4]. Various research has studied the cause of this phenomenon, providing a theoretical basis for future research on this topic [5,6,7,8,9,10,11]. The rapid development of GNSS technology has made it possible to observe the ionosphere continuously over a long period of time. Compared with traditional ionospheric observation methods, the global GNSS reference stations cover a wide area and can provide continuous observation data with high temporal resolution. The above advantages are the prerequisite for applying GNSS technology to the research of EIA phenomenon.

Objectives

Results

Conclusion