Global mean and extreme tropical cyclone (TC) precipitation has been increasing and is expected to continue to increase into the future due to climate change. While climate models project that precipitation will increase mainly in the TC inner core, data from satellite observations show a decrease in mean TC inner core precipitation over time and an increase in the outer rainbands since 1998. This work uses convection-permitting Weather Research and Forecasting (WRF) model simulations to investigate if this discrepancy between models and observations is related to coarse model resolutions used in past studies. The simulations are idealized, with single TCs initialized from weak vortices over domain-constant sea surface temperatures (SSTs). In these simulations, TC intensity and inner core precipitation greatly increase with SST warming while outer rainband precipitation increases slightly. More of the inner core is occupied by convection more frequently in the warmer simulations, while the convective activity remains constant with warming in the TC outer region. Mixing ratios of hydrometeors and cloud ice increase with warming in both the inner core and outer rainbands, while the TCs’ vertical circulations deepen and mean upward velocities strengthen. Results suggest that even convection-permitting models do not capture a decrease in TC inner core precipitation with warming, albeit in an idealized model set-up. This work demonstrates how analysis of three-dimensional storm mode structures can provide insight into processes that change TC precipitation in different regions of the storm, and future work will include applying this analysis to more realistic convection-permitting simulations.

NASA’s Investigations of Convective Updrafts (INCUS) mission aims to document convective updraft mass flux through changes in the radar reflectivity (ΔZ) in convective cores captured by a constellation of three Ka-band radars sampling the same convective cells over intervals of 30, 90 and 120 s. Here, high spatiotemporal resolution observations of convective cores from surface-based radars that use agile sampling techniques are used to evaluate aspects of the INCUS measurement approach using real observations. Analysis of several convective cells confirms that large coherent ΔZ structure with measurable signal (> 5 dB) can occur in less than 30 s and are correlated with underlying convective motions. The analysis indicates that the INCUS mission radar footprint and along track sampling are adequate to capture most of the desirable ΔZ signals. This unique demonstration of reflectivity time-lapse provides the framework for estimating convective mass flux independent from Doppler techniques with future radar observations.

Hazards from convective weather pose a serious threat to the continental United States (CONUS) every year. Previous studies have examined how future projected changes in climate might impact the frequency and intensity of severe weather using simulations with both convection-permitting regional models and coarser climate and Earth system models. However, many of these studies have been limited to single representations of the future climate state with little insight into the uncertainty of how the population of convective storms may evolve. To thoroughly explore this aspect, a large ensemble of Earth system model simulations was implemented to investigate how forced responses in large-scale convective environments might be modulated by internal climate variability. Daily data from an ensemble of 50 simulations with the most recent version of the Community Earth System Model was used to examine changes in the severe weather environment over the eastern CONUS during boreal spring from 1870-2100. Results indicate that forced changes in convective environments were small between 1870 and 1990, but throughout the 21st century, convective available potential energy and atmospheric stability (convective inhibition) is projected to increase while 0-6 km vertical wind shear decreases. Internal climate variability can either significantly enhance or suppress these forced changes. The time evolution of bivariate distributions of convective indices illustrates that future springtime convective environments over the eastern CONUS will be characterized by relatively less frequent, less organized, but deeper, more intense convection. Future convective environments will also be less supportive of the most severe convective modes and associated hazards.

Continued climate warming, together with the overall evaluation and implementation of a range of climate mitigation and adaptation approaches, has prompted increasing research into proposed solar climate intervention (SCI) methods, such as stratospheric aerosol injection (SAI). SAI would use aerosols to reflect a small amount of incoming solar radiation away from Earth to stabilize or reduce future warming due to increasing greenhouse gas concentrations. Research into the possible risks and benefits of SAI relative to the risks from climate change is emerging. There is not yet, however, an adequate understanding of how SAI might impact human and natural systems. For instance, little to no research to date has examined how SAI might impact environmental conditions critical to the formation of severe convective weather over the United States (U.S.). This study uses ensembles of Earth system model simulations of future climate change, with and without hypothetical SAI deployment, to examine possible future changes in thermodynamic and kinematic parameters critical to the formation of severe weather during convectively active seasons over the U.S. Results show that simulated forced changes in thermodynamic parameters are significantly reduced under SAI relative to a no-SAI world, while simulated changes in kinematic parameters are more difficult to distinguish. Also, unforced internal climate variability is likely to significantly modulate the projected forced climate changes over large regions of the U.S.