@article{21035, abstract = {According to the scientific consensus, tropical convection must decrease with global warming. This decrease is manifested by a decrease of the mass transported in the upward branch of the atmospheric overturning circulation – the convective mass flux – and a connected decrease of high clouds in the tropics, with implications for climate sensitivity. By using kilometer-scale simulations in radiative-convective equilibrium and a convective tracking algorithm, we show that no such decrease occurs in storms when taken individually and that the mass transport per storm increases instead. Storms can achieve this result by aggregating more surface of the convective cores – the inner part of the storm doing the vertical transport – so that the decrease of tropical convection is actually explained by a decrease in the total number of storms. There is little variation of the mean pressure velocity in the cores of the storms, a robust finding of this study. This remarkable invariance of the mean pressure velocity points to an emerging property of convection that should receive more attention in future studies.}, author = {Bolot, Maximilien and Roca, Rémy and Fiolleau, Thomas and Muller, Caroline J}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, publisher = {Springer Nature}, title = {{No decrease of tropical convection in individual deep convective systems with global warming}}, doi = {10.1038/s41612-025-01285-5}, volume = {9}, year = {2026}, } @article{19080, abstract = {We examine mesoscale convective organisation in the tropical western Pacific using a multivariate analysis of column humidity, precipitation and sea surface temperature (SST) observations. We demonstrate that in boreal summer and autumn, convection remains spatially random despite radiative-feedbacks acting to aggregate convection, which we attribute to the high density of convective moisture sources and the role of wind shear. Instead, in winter and spring, a weak meridional SST gradient exists and convection is usually clustered over the regions of warmer SSTs, with significant meridional humidity gradients. However, this is sporadically interrupted by episodes of convection migration to the coldest SSTs and limited spatial humidity variance. These episodes are the result of westward propagating equatorial waves, which remove meridional humidity gradients. It appears that the drivers of mesoscale convective clustering and humidity variability in the Pacific warm pool are the SST gradients, shear, and equatorial wave dynamics.}, author = {Tompkins, Adrian Mike and Casallas Garcia, Alejandro and De Vera, Michie Vianca}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, publisher = {Springer Nature}, title = {{Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific}}, doi = {10.1038/s41612-024-00848-2}, volume = {8}, year = {2025}, } @article{20026, abstract = {Deep Convective Systems (DCSs) reaching scales of 100–1000 km play a pivotal role as the primary precipitation source in the tropics. Those systems can have large cloud shields, and thus not only affect severe precipitation patterns but also play a crucial part in modulating the tropical radiation budget. Understanding the complex factors that control how these systems grow and how they will behave in a warming climate remain fundamental challenges. Research efforts have been directed, on one hand, towards understanding the environmental control on these systems, and on the other hand, towards exploring the internal potential of systems to develop and self-aggregate in idealized simulations. However, we still lack understanding on the relative role of the environment and internal feedbacks on DCS mature size and why. The novel high-resolution global SAM simulation from the DYAMOND project, combined with the TOOCAN Lagrangian tracking of DCSs and machine learning tools, offers an unprecedented opportunity to explore this question. We find that a system’s growth rate during the first 2 h of development predicts its final size with a Pearson correlation coefficient of 0.65. Beyond this period, growth rate emerges as the strongest predictor. However, in the early stages, additional factors–such as ice water path heterogeneity, migration distance, interactions with neighboring systems, and deep shear–play a more significant role. Our study quantitatively assesses the relative influence of internal versus external factors on the mature cloud shield size. Our results show that system-intrinsic properties exert a stronger influence than environmental conditions, suggesting that the initial environment does not strictly constrain final system size, particularly for larger systems where internal dynamics dominate.}, author = {Abramian, Sophie and Muller, Caroline J and Risi, Camille and Fiolleau, Thomas and Roca, Rémy}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, publisher = {Springer Nature}, title = {{How key features of early development shape deep convective systems}}, doi = {10.1038/s41612-025-01154-1}, volume = {8}, year = {2025}, } @article{18708, abstract = {This study investigates the response of Indian summer monsoon (ISM) precipitation to CO2 removal, with a specific focus on regional and subseasonal variations. Following CO2 removal, monsoon circulation weakens throughout the summer owing to the reduced large-scale meridional temperature gradient around India. Weakened monsoon circulation decreases the local-scale thermodynamic stability within India, following monsoon-onset periods. While the frequency of synoptic-scale ISM low-pressure systems (LPSs) decreases overall, the lower thermodynamic stability causes the LPSs to form and resultantly shift west and south from their typical paths, last longer and move more quickly zonally during August and September. Changes in these rain-producing processes induce distinct regional (Western Ghats, south-central-east India, and Tamil Nadu) and subseasonal precipitation responses. Also, extreme precipitation exhibits similar patterns, but is more strongly affected by changes in LPS. Our results suggest that reliable future projections of regional hydroclimate change require a more accurate understanding of multi-scale precipitation processes.}, author = {Paik, Seungmok and Kim, Daehyun and An, Soon Il and Oh, Hyoeun and Shin, Jongsoo and Goswami, Bidyut B and Min, Seung Ki and Mondal, Sanjit Kumar}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, publisher = {Springer Nature}, title = {{Exploring causes of distinct regional and subseasonal Indian summer monsoon precipitation responses to CO2 removal}}, doi = {10.1038/s41612-024-00858-0}, volume = {7}, year = {2024}, } @article{13256, abstract = {The El Niño-Southern Oscillation (ENSO) and the Indian summer monsoon (ISM, or monsoon) are two giants of tropical climate. Here we assess the future evolution of the ENSO-monsoon teleconnection in climate simulations with idealized forcing of CO2 increment at a rate of 1% year-1 starting from a present-day condition (367 p.p.m.) until quadrupling. We find a monotonous weakening of the ENSO-monsoon teleconnection with the increase in CO2. Increased co-occurrences of El Niño and positive Indian Ocean Dipoles (pIODs) in a warmer climate weaken the teleconnection. Co-occurrences of El Niño and pIOD are attributable to mean sea surface temperature (SST) warming that resembles a pIOD-type warming pattern in the Indian Ocean and an El Niño-type warming in the Pacific. Since ENSO is a critical precursor of the strength of the Indian monsoon, a weakening of this relation may mean a less predictable Indian monsoon in a warmer climate.}, author = {Goswami, Bidyut B and An, Soon Il}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, publisher = {Springer Nature}, title = {{An assessment of the ENSO-monsoon teleconnection in a warming climate}}, doi = {10.1038/s41612-023-00411-5}, volume = {6}, year = {2023}, }