Open AccessRegional 3‐D ionospheric electron density specification on the basis of data assimilation of ground‐based GNSS and radio occultation data
Author(s) -
Aa Ercha,
Liu Siqing,
Huang Wengeng,
Shi Liqin,
Gong Jiancun,
Chen Yanhong,
Shen Hua,
Li Jianyong
Publication year - 2016
Publication title -
space weather
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 56
ISSN - 1542-7390
DOI - 10.1002/2016sw001363
Subject(s) - ionosphere , radio occultation , gnss applications , data assimilation , tec , total electron content , longitude , ionosonde , international reference ionosphere , geodesy , geology , meteorology , electron density , remote sensing , latitude , satellite , environmental science , geography , geophysics , physics , astronomy , electron , quantum mechanics
Abstract In this paper, a regional 3‐D ionospheric electron density specification over China and adjacent areas (70°E–140°E in longitude, 15°N–55°N in latitude, and 100–900 km in altitude) is developed on the basis of data assimilation technique. The International Reference Ionosphere (IRI) is used as a background model, and a three‐dimensional variational technique is used to assimilate both the ground‐based Global Navigation Satellite System (GNSS) observations from the Crustal Movement Observation Network of China (CMONOC) and International GNSS Service (IGS) and the ionospheric radio occultation (RO) data from FORMOSAT‐3/COSMIC (F3/C) satellites. The regional 3‐D gridded ionospheric electron densities can be generated with temporal resolution of 5 min in universal time, horizontal resolution of 2° × 2° in latitude and longitude, and vertical resolution of 20 km between 100 and 500 km and 50 km between 500 and 900 km. The data assimilation results are validated through extensive comparison with several sources of electron density information, including (1) ionospheric total electron content (TEC); (2) Abel‐retrieved F3/C electron density profiles (EDPs); (3) ionosonde f o F 2 and bottomside EDPs; and (4) the Utah State University Global Assimilation of Ionospheric Measurements (USU‐GAIM) under both geomagnetic quiet and disturbed conditions. The validation results show that the data assimilation procedure pushes the climatological IRI model toward the observation, and a general accuracy improvement of 15–30% can be expected. Thecomparisons also indicate that the data assimilation results are more close to the Center for Orbit Determination of Europe (CODE) TEC and Madrigal TEC products than USU‐GAIM. These initial results might demonstrate the effectiveness of the data assimilation technique in improving specification of local ionospheric morphology.