Zhang et al. (2025) Analysis of Monsoon Characteristics in China Based on Precipitable Water Vapor Derived From GNSS and ERA5 Over 2016–2020

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2025
• Date: 2025-11-19
• Authors: Zhixuan Zhang, Yidong Lou, Weixing Zhang, Xianjie Li, Jan Douša, Hong Guan, Yunchang Cao, Hong Liang
• DOI: 10.1029/2025jd044441

Research Groups

Not explicitly stated in the abstract. The study utilized data from a dense network of over 1,000 Global Navigation Satellite System (GNSS) stations across China.

Short Summary

This study characterized the Asian Summer Monsoon (ASM) over China by retrieving precipitable water vapor (PWV) grid products from GNSS data and ERA5 reanalysis for 2016-2020. It found the average monsoon onset from late May to mid-June and retreat in September, advancing unevenly from southeast to northwest across China.

Objective

• To characterize the Asian Summer Monsoon (ASM) over China by understanding the distribution and variability of precipitable water vapor (PWV) using a dense network of GNSS data and ERA5 meteorological data.

Study Configuration

• Spatial Scale: National scale for China, utilizing over 1,000 densely distributed GNSS stations to generate grid products.
• Temporal Scale: 5 years, from 2016 to 2020.

Methodology and Data

• Models used:
  • Random forest machine learning method (employed for data imputation of GNSS-derived PWV using ERA5-derived PWV).
• Data sources:
  • Global Navigation Satellite System (GNSS) data from over 1,000 stations in China (used to obtain zenith tropospheric delays, ZTDs).
  • ERA5 meteorological data (used in combination with ZTDs to retrieve PWV, and for data imputation).

Main Results

• The average monsoon onset in China occurs from late May to mid-June (Day of Year (DOY) 150–170).
• The monsoon retreat in China takes place in September (DOY 252–274).
• The interannual variability of both monsoon onset and retreat times is approximately 10 days.
• The monsoon generally advances from southeast to northwest across China with an uneven speed.
• The bimodality of PWV statistical distribution was utilized, and a suitable metric was selected to quantify monsoon impact across different regions.
• Normalized Precipitable Water Indexes (NPWI) were constructed based on temporal variations in PWV to describe monsoon movement characteristics.

Contributions

• First comprehensive characterization of the Asian Summer Monsoon (ASM) over China using a dense network of over 1,000 GNSS stations for precipitable water vapor (PWV) retrieval.
• Development and application of a random forest machine learning method for robust imputation of data gaps in GNSS-derived PWV products, ensuring data integrity.
• Quantification of monsoon impact through the analysis of PWV statistical distribution bimodality and the introduction of Normalized Precipitable Water Indexes (NPWI) to describe monsoon movement.
• Precise determination of average monsoon onset and retreat times, along with their interannual variability, across China.

Funding

Not explicitly stated in the abstract.

Citation

@article{Zhang2025Analysis,
  author = {Zhang, Zhixuan and Lou, Yidong and Zhang, Weixing and Li, Xianjie and Douša, Jan and Guan, Hong and Cao, Yunchang and Liang, Hong},
  title = {Analysis of Monsoon Characteristics in China Based on Precipitable Water Vapor Derived From GNSS and ERA5 Over 2016–2020},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2025},
  doi = {10.1029/2025jd044441},
  url = {https://doi.org/10.1029/2025jd044441}
}