Regional Validation of Jason-2 Dual-Frequency Ionosphere Delays

Abstract

In this study, we validated the Jason-2 (J2) dual-frequency ionosphere delay measurements in terms of vertical total electron content (VTEC) in the Geophysical Data Record (GDR) with the coarse resolution JPL Global Ionospheric Maps (GIM), the regional ionospheric maps generated by the Crustal Motion Observation Network of China (CMONOC), and the Jason-1 (J1) interleaved tandem mission (with J2) ionosphere delay measurements. The estimates of the relative biases and their uncertainties (95% confidence, in TEC units) for various comparison cases with different data spans and regions are (1) J2–GIM: −3.07 ± 0.18 TECu (or 6.75 ± 0.40 mm in the range delay), (2) J2–CMONOC: −2.87 ± 0.38 TECu (6.31 ± 0.84 mm), (3) J1–GIM: −0.19 ± 0.18 TECu (0.42 ± 0.40 mm), and (4) J2–J1 via double-differencing, that is, (J2–GIM)–(J1–GIM): −2.88 ± 0.26 TECu (6.34 ± 0.57 mm). The scatter (RMS, about the mean differences) between J2 and GIM, CMONOC, or J1 is about 3∼8 TECu (6.6∼17.6 mm). We conclude that the results from global and regional analysis are consistent and that the J2 ionosphere delay is about 6∼10 mm (95% confidence) shorter than the delay computed by GIM, J1, or the regional model.

Keywords:

• Ionosphere delay
• total electron content
• Satellite altimetry

Acknowledgements

This research is supported by grants from NSF's National Space Weather Program (ATM-0418844), and from NASA's Ocean Science Topography Mission Program (JPL 1356532, and U. Colorado 154-5322). The Shanghai Astronomical Observatory component of the study is supported by the Chang’E-1 VLBI tracking project, and by the BeiDou GNSS Ionospheric Modeling Project. We thank the Crustal Movement Observation Network of China (CMONOC) for providing the high-level GPS VTEC data products used in this study.

Notes

*During the Jason-1/2 formation flight phase, corresponding to Jason-1 cycles 240–259. Computed by using the Stackfile approach (Yi 2000)

Figure 6 Comparison of daily averaged Jason-2 and Jason-1 tandem mission ionosphere delays (in TECu). Upper panel: direct-difference of J1–GIM and J2–GIM. The average value is −0.19 ± 0.18 TECu (or 0.42 ± 0.40 mm) for J1–GIM, and −3.07 ± 0.18 TECu (or 6.75 ± 0.40 mm) for J2–GIM. Lower panel: double-difference of (J1–GIM)–(J2–GIM) and linear fitting.