Projected Changes in the Month-to-Month Evolution of Winter Precipitation in Northeastern Asia Under Global Warming

Winter precipitation in Northeastern Asia has important implications for regional climate and weather hazards, yet its month-to-month evolution under global warming remains poorly understood. Using observations and the Policy Decision-making for Future climate change (d4PDF) large-ensemble simulations, this study investigates winter precipitation from November to March (NDJFM) and its projected changes under +2 K and +4 K global warming. Observations show a broadly U-shaped month-to-month evolution, with less precipitation in midwinter than at the beginning and end of winter. d4PDF generally reproduces the observed spatial pattern and month-to-month evolution, despite some regional biases. Winter precipitation is projected to increase across Northeastern Asia, with larger relative increases over the dry continental regions. Warming also reorganizes the monthly distribution of precipitation: the U-shaped evolution generally weakens, while the direction of subseasonal shifts varies regionally. Moisture-budget analysis indicates that submonthly moisture transport plays an important role in wintertime moisture convergence and its projected changes. Over the continental regions, enhanced submonthly moisture convergence offsets changes associated with the monthly mean flow, while thermodynamic effects dominate changes in the monthly component.