Research

Stratocumulus cloud response to climate change

How will stratocumulus clouds respond dynamically to increased concentrations of atmospheric CO2?

  • Stratocumulus clouds are sustained through cloud-top longwave cooling that drives their unique upside-down convection.
  • They are prevalent only in certain regions (e.g. off the coast of California) because they exist through a delicate balance of cool ocean temperatures below and a strong temperature inversion at the top of the boundary layer created from subsiding free-tropospheric air.
  • Increasing CO2 concentrations will lead to weaker cloud-top cooling, increased surface temperatures and latent heat fluxes, and changing large-scale circulation and subsidence. All of these impact the dynamics of stratocumulus clouds.
  • We are developing a theoretical model to explain the breakup of stratocumulus clouds to increased CO2.

Read the preprints here:

3D cloud radiative effects

How large is the albedo bias in climate models resulting from 1D radiative transfer assumptions?

Read the paper here: https://doi.org/10.1175/JAS-D-21-0032.1

Fig 1. Top-of-atmosphere flux (a) and albedo (b) bias as a function of solar zenith angle for various cloud types: shallow cumulus (BOMEX and RICO), stratocumulus (DYCOMS-II RF01), deep convection (TRMM-LBA and TRMM-LBA agg.).

Fig 2. Zonal-mean and map of annual-mean flux bias inferred from ISCCP cloud water path. Bias is smallest over stratocumulus regions and largest over the ITCZ and storm tracks, areas with deep clouds and persistent cloudiness.

In collaboration with: Ignacio Lopez-Gomez, Sally Zhang, and Tapio Schneider

Aerosol-cloud interactions

What is the importance of aerosol hygroscopicity in cloud dynamics?

  • I am quantifying the impact of aerosol hygroscopicity using large-eddy simulations (LES) with Lagrangian particle-based microphysics (superdroplets).
  • This research is being done using the University of Warsaw Lagrangian Cloud Model.
  • This research has implications for understanding the efficacy of and optimal seeding strategies for Marine Cloud Brightening.
  • In collaboration with Anna Jaruga and John Seinfeld.

Open-source tools for particle-based microphysics modeling

  • I am a contributor to PySDM and PySDM-examples, an open-source microphysics code with examples that uses particle-based methods.
  • I am developing and using this tool to investigate rarely included effects of surface-partitioning by organic aerosol on droplet activation.
  • This work is being done with collaborators Sylwester Arabas and Ryan Ward.

The Climate Modeling Alliance (CliMA)

I am the main developer of Insolation.jl, a planet-agnositic insolation code used by CliMA.

Convective transport in the Asian Summer Monsoon (ASM)

What is the role of convection within the ASM on stratophseric composition? To what extent does the ASM govern exchange between the troposphere and stratosphere?

  • Our group used water vapor isotopes (HDO/H2O) to quantify the role of convection on transport to the UTLS in the ASM.
  • This research was done as part of the StratoClim aircraft campaign in summer 2017, with 8 research flights based out of Kathmandu, Nepal.
  • I led the intercomparison of three in-situ water vapor measurements (doi: 10.5194/amt-15-4767-2022).
  • Collaborators led complementary studies on the role of hydration/dehydration (doi: 10.5194/acp-22-3169-2022) and the use of isotopes as tracers of convection.

In collaboration with: Dr. Ben Clouser and Dr. Liz Moyer