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<p>Predicting seasonal precipitation at regional scales with coupled models is challenging but essential for many applications. In this study, we compare the skills of the Monsoon Mission Coupled Forecast System version 2 (MMCFSv2) model in reproducing precipitation over five homogeneous regions of India; Northeast India (NEI), Northwest India (NWI), Central Northeast India (CNEI), West Central India (WCI), and South Peninsula India (SPI) during 1998–2022, compared with the previous version (MMCFSv1). We examine why MMCFSv2 better captures interannual variability and correlation than MMCFSv1, as well as the remaining challenges in regional forecasting. MMCFSv2 (MMCFSv1) shows seasonal mean precipitation skill of 0.72 (0.54) in the All-India Region (AIR), 0.38 (0.09) in CNEI, 0.66 (0.60) in WCI, 0.55 (0.45) in SPI, -0.18 (-0.42) in NEI, and 0.21 (0.53) in NWI. Rainfall over homogeneous regions is strongly teleconnected to Indo-Pacific Sea Surface Temperatures (SST), with the NWI influenced by the Arabian Sea (AS) and the others by tropical Pacific and Southern Indian Ocean (SIO) SSTs. MMCFSv2 simulates SIO and tropical Pacific SSTs well, particularly in the Niño 3.4, and Indian Ocean Dipole regions; however, it fails to capture AS SSTs, resulting in lower skill over NWI. Despite improved performance over these regions and AIR rainfall, MMCFSv2 underestimates southwestern WCI and northern SPI rainfall, shows a high July and August dry bias, and struggles with extremes along the Western Ghats and deficiencies over NWI. Seasonal mean precipitation bias values for MMCFSv2 (MMCFSv1) are − 1.50 (−&#xa0;1.03) mm/day in WCI and 0.96 (0.55) mm/day in SPI. MMCFSv2 exhibits a stronger wet bias over NEI (June –September) and over northern CNEI near the Himalayan foothills (July–August). The standard deviation of rainfall is underestimated over northern CNEI (July), western NEI (June), and NWI (July-September). These findings highlight the limitations of MMCFSv2 in complex orographic regions and NWI, emphasizing the challenges for future development of regional rainfall prediction.</p>

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Seasonal prediction of summer monsoon rainfall over homogeneous regions of india: evolution of monsoon mission coupled climate models

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Nanaji Rao Nellipudi,
  • Suryachandra A. Rao,
  • Deepeshkumar Jain,
  • Prasanth A. Pillai,
  • Ankur Srivastava,
  • Maheswar Pradhan

摘要

Predicting seasonal precipitation at regional scales with coupled models is challenging but essential for many applications. In this study, we compare the skills of the Monsoon Mission Coupled Forecast System version 2 (MMCFSv2) model in reproducing precipitation over five homogeneous regions of India; Northeast India (NEI), Northwest India (NWI), Central Northeast India (CNEI), West Central India (WCI), and South Peninsula India (SPI) during 1998–2022, compared with the previous version (MMCFSv1). We examine why MMCFSv2 better captures interannual variability and correlation than MMCFSv1, as well as the remaining challenges in regional forecasting. MMCFSv2 (MMCFSv1) shows seasonal mean precipitation skill of 0.72 (0.54) in the All-India Region (AIR), 0.38 (0.09) in CNEI, 0.66 (0.60) in WCI, 0.55 (0.45) in SPI, -0.18 (-0.42) in NEI, and 0.21 (0.53) in NWI. Rainfall over homogeneous regions is strongly teleconnected to Indo-Pacific Sea Surface Temperatures (SST), with the NWI influenced by the Arabian Sea (AS) and the others by tropical Pacific and Southern Indian Ocean (SIO) SSTs. MMCFSv2 simulates SIO and tropical Pacific SSTs well, particularly in the Niño 3.4, and Indian Ocean Dipole regions; however, it fails to capture AS SSTs, resulting in lower skill over NWI. Despite improved performance over these regions and AIR rainfall, MMCFSv2 underestimates southwestern WCI and northern SPI rainfall, shows a high July and August dry bias, and struggles with extremes along the Western Ghats and deficiencies over NWI. Seasonal mean precipitation bias values for MMCFSv2 (MMCFSv1) are − 1.50 (− 1.03) mm/day in WCI and 0.96 (0.55) mm/day in SPI. MMCFSv2 exhibits a stronger wet bias over NEI (June –September) and over northern CNEI near the Himalayan foothills (July–August). The standard deviation of rainfall is underestimated over northern CNEI (July), western NEI (June), and NWI (July-September). These findings highlight the limitations of MMCFSv2 in complex orographic regions and NWI, emphasizing the challenges for future development of regional rainfall prediction.