Gyawali et al. (2026) Quantifying the Ratio of Non‐Synoptically Forced Precipitation Events Over CONUS Using the Quasigeostrophic Omega Equation

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

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2026
• Date: 2026-07-04
• Authors: Nabindra Gyawali, Brian E. J. Rose, Craig R. Ferguson
• DOI: 10.1029/2026jd047250

Research Groups

• National Aeronautics and Space Administration (NASA)
• University research groups focused on atmospheric science and hydrology

Short Summary

This study introduces a classification scheme for precipitation events based on synoptic-scale forcing, which reveals a strong south-north gradient in the ratio of non-synoptically to total precipitation events across the continental United States.

Objective

• Investigate the role of land-atmosphere coupling in regimes of weak synoptic forcing by developing a classification scheme for precipitation events

Study Configuration

• Spatial Scale: Continental United States (CONUS)
• Temporal Scale: 3-hourly, with seasonal and interannual variability analysis

Methodology and Data

• Models used: Quasigeostrophic (QG) omega equation
• Data sources: NASA's MERRA-2 reanalysis, IMERG precipitation data set, satellite sounder data

Main Results

• The mean ratio of non-synoptic to total precipitation events exhibits a strong south-north gradient from 0.7 at 25°N to 0.35 at 50°N in the zonal average.
• Strong seasonality is observed, with synoptically driven precipitation dominant in winter and a non-synoptic precipitation ratio exceeding 0.8 in the southern half of CONUS in summer.
• Interannual variability in the non-synoptic precipitation frequency is largest in the southern CONUS.

Contributions

• The study provides new insights into the role of land-atmosphere coupling in regimes of weak synoptic forcing, which can improve our understanding of precipitation patterns and forecasting challenges over land.

Funding

• NASA's MERRA-2 reanalysis was funded by NASA's Earth Science Division (ESD)
• IMERG precipitation data set was funded by NASA's Precipitation Measurement Mission (PMM)

Citation

@article{Gyawali2026Quantifying,
  author = {Gyawali, Nabindra and Rose, Brian E. J. and Ferguson, Craig R.},
  title = {Quantifying the Ratio of Non‐Synoptically Forced Precipitation Events Over CONUS Using the Quasigeostrophic Omega Equation},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2026},
  doi = {10.1029/2026jd047250},
  url = {https://doi.org/10.1029/2026jd047250}
}