Daniel Hernandez-Deckers

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations of two cases during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) near Houston, Texas, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, leading to more lightning. Polluted thermals initiate at slightly higher altitudes, and are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, but fewer isolated cells, since convection is more aggregated and intense, especially near the end of the 24 h simulation. Non-linear mesoscale feedback likely triggered by temperature and moisture responses to aerosol-thermal interactions causes the aggregation. Time-lagged aerosol-reinitialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

In cumulus clouds, aerosol concentrations control cloud droplet concentrations, modifying cloud radiative properties, precipitation processes, and cloud electrification. However, mechanisms of aerosol-deep convection interactions are not well understood due to complex cloud dynamics and microphysics. We investigate the interaction of aerosols with isolated deep convection using Large Eddy Simulations during the TRacking Aerosol Convection interactions ExpeRiment (TRACER) in the Houston area, using a joint cell-thermal tracking algorithm. Cumulus thermals are droplet generators, since supersaturation and droplet nucleation coincide with thermal centers, where the strongest updrafts occur. Primary ice crystal formation does not take place inside thermals, but at layers where previous thermals detrained moisture. As subsequent thermals containing supercooled droplets penetrate these layers, hail and graupel form at or near these thermals. Higher aerosol concentrations result in higher droplet concentrations that suppress drizzle, delay warm rain processes, and transport more moisture aloft. This increases snow and ice amount, as well as graupel and hail, also associated with more lightning. Also, thermals initiate slightly higher, are slightly larger and faster, suggesting a weak invigoration. We also find more thermals per cell, albeit fewer isolated cells. Convection aggregates more, explaining the lower isolated cell count, and enhancing convection, especially near the end of the 24-hour integration. This non-linear mesoscale feedback is likely triggered by temperature and moisture responses due to aerosol-thermal interactions. Additional time-lagged aerosol-reinialization experiments show that the mesoscale response is the predominant forcing for the invigoration. These changes happen within one day, on a smaller scale than previously suggested.

Improving parameterizations of convective microphysics in Earth system models (ESMs) requires well-constrained cases suitable for scaling between cloud-resolving models and ESMs. We propose a benchmark large eddy simulation (LES) cumulus congestus case study from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP²Ex) and demonstrate its observational constraints using novel polarimetric retrievals and in situ cloud microphysics measurements. Simulations using bulk and bin microphysics with observed aerosol input are compared to cloud-top retrievals of cloud droplet effective radius (R_eff) and number concentration (N_d) from the airborne Research Scanning Polarimeter (RSP). The bulk scheme reasonably reproduces characteristic profiles of cloud-top N_d that decrease with altitude, while the bin simulation realizes greater discrepancies due to weaker precipitation formation. The N_d profile is strongly sensitive to the collision-coalescence process and the vertically resolved aerosol distribution, but appears well-constrained, whereas a persistent low-bias in R_eff is evident in both schemes. Comparison of simulated and in situ droplet size distributions (DSDs) show that low-biased R_eff originates from a cloud droplet mode that is too narrow relative to observations. Finally, a thermal-tracking framework demonstrates that the dilution of N_d throughout a thermal's lifetime is heavily determined by collision-coalescence and the height-varying aerosol distribution, and that in the absence of these, the impact of entrainment on diluting N_d is largely offset by continuous aerosol activation. Implications for developing warm-phase convective microphysics schemes for ESMs, evaluation of cumulus congestus using single column model versions of ESMs, and translating results to global, space-based polarimetry platforms are discussed.