Simultaneous influences of thermodynamics and aerosols on deep convection and lightning in the tropics

Convective features (CFs) observed by the Tropical Rainfall Measuring Mission satellite between 2004 and 2011 are analyzed to determine the relative roles of thermodynamics and aerosols as they modulate radar reflectivity and lightning. We studied the simultaneous impacts of normalized convective av...

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Bibliographic Details
Published in:Journal of geophysical research. Atmospheres 2015-06, Vol.120 (12), p.6207-6231
Main Authors: Stolz, Douglas C., Rutledge, Steven A., Pierce, Jeffrey R.
Format: Article
Language:English
Subjects:
Aerosols
Air traffic control
Clouds
convection
Geophysics
Lightning
precipitation
Radar
Rainfall measurement
Reflectivity
Thermodynamics
Tropics
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Summary:Convective features (CFs) observed by the Tropical Rainfall Measuring Mission satellite between 2004 and 2011 are analyzed to determine the relative roles of thermodynamics and aerosols as they modulate radar reflectivity and lightning. We studied the simultaneous impacts of normalized convective available potential energy (NCAPE) and warm cloud depth (WCD) as well as cloud condensation nuclei concentrations (D ≥ 40 nm; N40) on total lightning density (TLD), average height of 30 dBZ echoes (AVGHT30), and vertical profiles of radar reflectivity (VPRR) within individual CFs. The results show that TLD increases by up to 600% and AVGHT30 increases by up to 2–3 km with increasing NCAPE and N40 for fixed WCD. The partial sensitivities of TLD/AVGHT30 to NCAPE and N40 separately were comparable in magnitude but account for a fraction of the total range of variability (i.e., when the influences of NCAPE and N40 are considered simultaneously). Both TLD and AVGHT30 vary inversely with WCD such that maxima of TLD and AVGHT30 are found for the combination of high NCAPE, high N40, and shallower WCD. The relationship between lightning and radar reflectivity was shown to vary as a function of N40 for a fixed thermodynamic environment. Analysis of VPRRs shows that reflectivity in the mixed phase region is up to 5.0–5.6 dB greater for CFs in polluted environments compared to CFs in pristine environments (holding thermodynamics fixed). This analysis favors a merged hypothesis for the simultaneous roles of thermodynamics and aerosols as they influence deep convective clouds in the Tropics. Key Points Aerosol‐thermodynamic‐convective cloud interactions are investigated Higher CCN concentrations and greater NCAPE lead to stronger convection Warm cloud depth modulates NCAPE‐CCN‐convection interplay
ISSN:2169-897X
2169-8996
DOI:10.1002/2014JD023033