This study used the pseudo-global warming (PGW) method in the Weather Research and Forecasting (WRF) model to examine the effects of climate change on localized heavy rainfall events in the Tohoku and Hokuriku regions in August 2022. This heavy rainfall event is one of the representative cases of heavy rainfall in the region, in which water vapor transport from the Sea of Japan is a key factor, and its frequency and magnitude are projected to increase with climate change. Our modeling results showed that the simulated 48-h precipitation under the projected 2090s warming conditions increased by 34.6 % compared to precipitation without consideration of future warming effects. In general, the amount of water vapor in the atmosphere and convection instability over the ocean increased with future warming. While the rate of increase in water vapor is generally consistent with Clausius-Clapeyron scaling (7 %/K) based on surface temperature rise, the 48-h cumulative precipitation notably exceeds this scaling rate, even larger than triple Clausius-Clapeyron scaling. This increase in precipitation is driven by a combination of thermodynamic effects—such as enhanced water vapor content with rising temperatures—and dynamic effects, including strengthened updrafts. We showed that the model domain location can significantly affect the simulated precipitation and its changes in PGW simulations. For instance, a 29.2 % change in 48-h precipitation was observed solely due to the geospatial shift of the innermost domain. This finding indicates the importance of the model domain location as a source of uncertainty in the PGW method.

中文翻译：

---

气候变化对 2022 年日本北部局部强降雨事件的影响——伪全球变暖方法的不确定性


本研究使用天气研究和预报 （WRF） 模型中的伪全球变暖 （PGW） 方法研究了气候变化对 2022 年 8 月东北和北陆地区局部强降雨事件的影响。这次强降雨事件是该地区强降雨的典型案例之一，其中来自日本海的水蒸气输送是一个关键因素，预计其频率和强度将随着气候变化而增加。我们的建模结果表明，在不考虑未来变暖效应的情况下，在预测的 2090 年代变暖条件下，模拟的 48 小时降水量增加了 34.6%。一般来说，大气中的水蒸气量和海洋上空的对流不稳定性随着未来变暖而增加。虽然水蒸气的增加速率通常与基于地表温度上升的 Clausius-Clapeyron 缩放 （7 %/K） 一致，但 48 h 累积降水量明显超过该缩放速率，甚至大于 Clausius-Clapeyron 缩放的三倍。降水的增加是由热力学效应（例如随着温度升高而增加的水蒸气含量）和动态效应（包括增强的上升气流）共同驱动的。我们表明，模型域位置可以显着影响 PGW 模拟中的模拟降水及其变化。例如，观察到 48 小时降水量变化 29.2% 完全是由于最内层域的地理空间偏移。这一发现表明了模型域位置作为 PGW 方法中不确定性来源的重要性。