Heavy rainfall is one of the major aspects of tropical cyclones (TC) and can cause substantial damages. Here, we show, based on satellite observational rainfall data and numerical model results, that between 1999 and 2018, the rain rate in the outer region of TCs has been increasing, but it has decreased significantly in the inner-core. Globally, the TC rain rate has increased by 8 ± 4% during this period, which is mainly contributed by an increase in rain rate in the TC outer region due to increasing water vapor availability in the atmosphere with rising surface temperature. On the other hand, the rain rate in the inner-core of TCs has decreased by 24 ± 3% during the same period. The decreasing trend in the inner-core rain rate likely results mainly from an increase in atmospheric stability.

The characteristics of tropical cyclones (TCs) and their response to climate change is an issue of broad concern. Based on the Power Dissipation Index (PDI) proposed by Emanuel in 2005, the destructiveness of TCs in the typhoon season (July-October) during the period 1979-2016 over the western North Pacific is investigated. Results show that a regime shift in the destructive potential of TCs took place around 1998. The destructive potential of TCs has a considerable increasing trend from 1998 to 2016 (the P2 period), mainly contributed by the average intensity of TCs (51.20% of PDI change). We find that the PDI of TCs is mainly regulated by the El Niño/Southern Oscillation cycle in whole study period, whereas the Pacific Decadal Oscillation pattern shows significant enhancement in P2, which acts as a more important constraint on the typhoon season PDI over the western North Pacific.

The relationship between the destructive potential of tropical cyclones (TCs) over the western North Pacific (WNP) (as quantified by the Power Dissipation Index) and El Niño events is investigated in this work. Results show that the destructive potential of TCs is significantly affected by how rapidly El Niño decays from a positive phase to a negative phase. For TCs occurring during 'slow-transforming' El Niño, more of them initiate over the southeastern part (0°-15°N, 150°E-180°) of the WNP and the destructive potential of TCs is usually strong. In contrast, weaker destructiveness is indicated during 'rapid-transforming' periods, with fewer TC formations in the southeastern area. This weaker destructiveness during rapid-transforming El Niño years is mainly caused by anomalously cooler upper-ocean conditions in the central Pacific, negative relative vorticity anomalies, and increased vertical wind shear in the WNP. These findings may have important implications for the seasonal prediction of TC changes in the WNP.

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