[IGSMAIL-8726] CAS-TECRecon30: new CAS global TEC maps with complete spatial coverage and 30-min sampling

[wangningbo at aoe.ac.cn]

Author: Ningbo Wang (wangningbo at aoe.ac.cn)

Dear colleagues, 

Global Ionospheric Maps (GIMs) describe the distribution of free electrons in Earth's upper atmosphere, and are widely used in satellite navigation and space weather studies. However, historical GIM records often contain substantial spatial gaps in regions with sparse ground-based GNSS coverage and were typically generated at a temporal resolution of only two hours.

At CAS, we have developed a two-stage machine-learning approach to reconstruct the missing grid values and generate global TEC maps at 30-minute intervals. The method was applied to the historical CAS final GIM products CASG, to produce a new global TEC dataset covering 1999-2025. For the period before 2016, the method reconstructs missing spatial values and increases the temporal resolution from two hours to 30 minutes. For later years, it filled the remaining occasional gaps while retaining the existing 30-minute sampling of CASG. Validation with independent GPS STEC observations yields mean RMS difference of 2.67 TECU, approximately 30% lower than that of the original CASG products. 

The CAS-TECRecon30 data set is publicly available from the CAS data center: 
https://data.bdsmart.cn/pub/product/iono/ionex/recon/ 

The archive contains global TEC maps for 1999-2025 with complete spatial coverage and 30-min sampling. The dataset will be continuously updated and maintained by CAS and is expected to support studies of ionospheric variability, as well as satellite navigation and space weather applications. 

Further information on the dataset, file format, and access instructions is provided in the README file: 
https://data.bdsmart.cn/pub/product/iono/ionex/recon/README.md 

A manuscript describing the methodology and validation results has been submitted for consideration for publication.

Ningbo Wang
on behalf of the CAS team

Ningbo WANG, Ph.D Associate Professor
Aerospace Information Research Institute (AIR)
Chinese Academy of Sciences (CAS)
No 9 Dengzhuang South Road
Beijing China

Tel (+86) 186 7401 0516
e-mail wangningbo at aoe.ac.cn
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