Literature Review Stolz D C S A Rutledge

Literature Review: Stolz, D. C. , S. A. Rutledge, and J. R. Pierce (2015), Simultaneous influences of thermodynamics and aerosols on deep convection and lightning in the tropics, J. Geophys. Res. Atmos. , 120, doi: 10. 1002/2014 JD 023033. Kyle Hilburn AT 740 April 16, 2019 1

Overview Subject: – – – • Thermodynamics Aerosols Deep Convection Lightning Tropics Datasets: – TRMM CF (PR + LIS) • 2004 -2011 • Version 7 – GEOS-Chem-TOMAS • GFED 3 biomass burning inventory • GEOS-Chem transport • TOMAS aerosol microphysics module – ERAi • Thermodynamic environment • Inflow swath to CFs • Main conclusions: – Higher CCN and NCAPE lead to stronger convection – WCD modules relationship High Flash Density 10, 000 N 40 (cm-3) • WCD 4. 5 -5 km 1, 000 100 WCD 2 -3. 5 km 10 0. 1 0. 2 0. 3 NCAPE (J kg-1 m-1) My cartoon summary of the paper, based on Figure 3 High Flash Density > 0. 005 fl min-1 km-2 High FD area shifts right and gets smaller with increasing WCD Median WCD is 4. 2 km • Inverse: greater TLD and H 30 with shallower WCD 2

Thermodynamic Hypothesis • Variability in lightning and convective intensity over continental and oceanic regions of tropics can be explained by differences in thermodynamic instability – Rutledge et al. 1992; Williams et al. 1992, 2002; Williams and Stanfill 2002; Williams and Sátori 2004 • Tropical land surfaces respond strongly to solar radiation; more energetic parcels ascend through deep BL and have less dilution via entrainment • Would expect more robust mixed phase microphysics and NIC over land 3

Aerosol Hypothesis • Number of CCN significantly influences microphysical properties and vertical development – Rosenfeld and Lensky 1998; Rosenfeld 1999; Rosenfeld et al. 2008; … and many more • Aerosol-induced convective invigoration – High CCN environment hinders collision-coalescence warm rain process • Less offloading of condensate – More cloud water transported to mixed phase region – Latent heat release provides increased buoyancy and greater charge separation 4

Warm Cloud Depth Hypothesis • WCD: distance between LCL and FL • WCD determines duration of ascent through warm phase region and time for collisioncoalescence to operate • Deeper WCD: cloud liquid lost before reaching mixed phase region • Shallow WCD: more cloud liquid reaches mixed phase region • Very shallow WCD (outside tropics): time for aerosols to impact collision-coalescence too short to see sensitivity to aerosols 5

Spatial Patterns Cloud Features Lightning Producing CFs All cloud features looks like precip map Many LPCFs but low FD over Amazon ”Green Ocean” Good correlation between H 30 and FD …. Price and Rind not looking so bad! S. Hem. FD hotspots for southern S. Am. and Africa, Australia with few LPCFs - high flash rate storms Aerosol ocean land H 30 FD CAPE Aerosol WCD NCAPE about same for ocean/land Strong mean spatial correlation between N 40 and FD High WCD over Amazon, central Africa; lower over southern S. Am. and Africa, SE US, and Australia 6

Lightning/Height vs NCAPE, N 40, and WCD • Results for lightning (left) and H 30 (above) similar • Highest TLD for N 40 > 1000 cm-3 and NCAPE > 0. 15 J kg-1 m-1 • High FD retreats to highest NCAPE and N 40 at deep WCD 7

Land vs Ocean • Same WCD effect over land ocean • Greater FD (left) and H 30 (above) over land than ocean 8

Partial Sensitivities • TLD has greater variability with N 40 than NCAPE (except over oceans) • Slope with NCAPE roughly constant, but variable for N 40 • Steepest slope for shallow WCD • Slope negative for low NCAPE, deep WCD, and high N 40 9

Shallow vs Deep Differences • Difference for shallow minus deep • Differences mostly > 0 • Maximum increases for higher NCAPE and higher N 40 10

Lightning/Reflectivity versus Aerosol • FD increases with H 30 (below) • FD greater for greater N 40 • Sensitivity decreases with decreasing N 40 • VPRR vs CAPE, WCD, N 40 (right) • Increase in reflectivity at given altitude for larger N 40 • Largest change in VPRR for shallower WCD 11

Summary and Conclusions • Highest flash rates (and highest 30 d. BZ echo heights) associated with combination of high NCAPE, high N 40, and shallower WCD • Reflectivity in mixed phase region 5. 0 -5. 6 d. B greater in polluted environment • Merged hypothesis for simultaneous roles of thermodynamics and aerosols influencing deep convection in tropics – Modulated by warm cloud depth 12

BACKUP SLIDES 13

Land/Ocean Cloud/Lightning Histograms N 40 different land/ocean, but NCAPE and WCD about the same 14

Tables 15