Extreme precipitation in the tropics is closely associated with long-lived convective systems

Abstract

Water and energy cycles are linked to global warming through the water vapor feedback and heavy precipitation events are expected to intensify as the climate warms. For the mid-latitudes, extreme precipitation theory has been successful in explaining the observations, however, studies of responses in the tropics have diverged. Here we present an analysis of satellite-derived observations of daily accumulated precipitation and of the characteristics of convective systems throughout the tropics to investigate the relationship between the organization of mesoscale convective systems and extreme precipitation in the tropics. We find that 40% of the days with more than 250 mm precipitation over land are associated with convective systems that last more than 24 hours, although those systems only represent 5% of mesoscale convective systems overall. We conclude that long-lived mesoscale convective systems that are well organized contribute disproportionally to extreme tropical precipitation.

Sharp rises in large-scale, long-duration precipitation extremes with higher temperatures over Japan

“…In particular, for the long-duration event under warmer temperature (Supplementary Fig. 3b), the larger area with high cloud tops (i.e., areas below −40°C) suggests a contribution of well-organized or long-lived mesoscale convective systems to the extreme event, as found in the tropics 29 .…”

“…npj Climate and Atmospheric Science (2021)29 Published in partnership with CECCR at King Abdulaziz University…”

A Simple Model for Tropical Convective Cloud Shield Area Growth and Decay Rates Informed by Geostationary IR, GPM, and Aqua/AIRS Satellite Data

“…Nearly all of the largest system‐average rainfall rates are found during system growth stages (Figure 5e). Since average rainfall peaks early in lifecycle composites (Feng et al., 2019, 2021; Fiolleau & Roca, 2013b) and longer‐lived systems contribute more to extreme precipitation (Feng et al., 2018; Roca & Fiolleau, 2020), this may imply that rainfall extremes specifically occur during growth periods of the early lifecycle stages. There is little relationship between growth and decay rates, life stage (Figure 5f), and moisture (Figures 5k–5n).…”

“…Mesoscale convective systems (MCSs) are the dominant sources of rainfall in the tropics (Moncrieff, 2019; Roca et al., 2014; Tao & Moncrieff, 2009). MCS cloud shields comprise convective regions whose spatial aggregation may be quantified via “organization metrics” (Holloway et al., 2017; Parker & Johnson, 2000; Retsch et al., 2020; Tobin et al., 2012, 2013) such that increased organization may be associated with larger cloud shields, longer lifetimes, and substantial rainfall accumulation (Liu, 2011; Liu et al., 2008; Roca & Fiolleau, 2020; Schiro et al., 2020). High resolution model simulations over domains populated by MCSs are frequent sources for deriving MCS radiation, cloud, and rainfall lifecycle evolutions (Feng et al., 2018, 2021; Hagos et al., 2013).…”

Shear-convection interactions, and orientation of tropical squall lines

“…Squall lines are associated with extreme rainfall, and an interesting question could be the impact of squall line orientation on extreme precipitation rates. In the longer term, more work is desirable to extend these results beyond the CRM framework, for example, by using satellite data (Fiolleau & Roca, 2013;Roca & Fiolleau, 2020). The deployment of satellite observations at fine-scale resolution (kilometers, for example within cold pools), such as those proposed in the ESA Harmony mission (the only Earth Explorer 10 candidate mission), would be essential to perfect our understanding of the processes (Harmony, 2020).…”