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Jean Garling - personal papers, 1897-1998, together with associated papers, 1823-1998

Series 1: Frederick Rose General Correspondence, [ca. 1930]-1991

The advent of the Visible Infrared Imager Radiometer Suite (VIIRS) on board the Suomi NPP (SNPP) satellite made it possible to retrieve a new class of convective cloud properties and the aerosols that they ingest. An automated mapping system of retrieval of some properties of convective cloud fields over large areas at the scale of satellite coverage was developed and is presented here. The system is named Automated Mapping of Convective Clouds (AMCC). The input is level-1 VIIRS data and meteorological gridded data. AMCC identifies the cloudy pixels of convective elements; retrieves for each pixel its temperature T and cloud drop effective radius re
; calculates cloud-base temperature Tb
based on the warmest cloudy pixels; calculates cloud-base height Hb
and pressure Pb
based on Tb
and meteorological data; calculates cloud-base updraft Wb
based on Hb
; calculates cloud-base adiabatic cloud drop concentrations Nd,a
based on the T–re
relationship, Tb, and Pb; calculates cloud-base maximum vapor supersaturation S based on Nd,a
and Wb
; and defines Nd,a
/1.3 as the cloud condensation nuclei (CCN) concentration NCCN
at that S. The results are gridded 36 km × 36 km data points at nadir, which are sufficiently large to capture the properties of a field of convective clouds and also sufficiently small to capture aerosol and dynamic perturbations at this scale, such as urban and land-use features. The results of AMCC are instrumental in observing spatial covariability in clouds and CCN properties and for obtaining insights from such observations for natural and man-made causes. AMCC-generated maps are also useful for applications from numerical weather forecasting to climate models.

Journal of applied meteorology and climatology, 2019-04, Vol.58 (4), p.887-902

Automated Mapping of Convective Clouds (AMCC) Thermodynamical, Microphysical, and CCN Properties from SNPP/VIIRS Satellite Data

Aerosol–cloud interactions contribute to the large uncertainties in current
estimates of climate forcing. We investigated the effect of aerosol particles
on cloud droplet formation by model calculations and aircraft measurements
over the Amazon and over the western tropical Atlantic during the
ACRIDICON–CHUVA campaign in September 2014. On the HALO (High
Altitude Long Range Research) research aircraft,
cloud droplet number concentrations (Nd) were measured near the
base of clean and polluted growing convective cumuli using a cloud combination
probe (CCP) and a cloud and aerosol spectrometer (CAS-DPOL). An adiabatic
parcel model was used to perform cloud droplet number closure studies for
flights in differently polluted air masses. Model input parameters included
aerosol size distributions measured with an ultra-high sensitive aerosol
spectrometer (UHSAS), in combination with a condensation particle counter
(CPC). Updraft velocities (w) were measured with a boom-mounted Rosemount
probe. Over the continent, the aerosol size distributions were dominated by
accumulation mode particles, and good agreement between measured and modeled
Nd values was obtained (deviations ≲ 10 %)
assuming an average hygroscopicity of κ∼0.1, which is consistent
with Amazonian biomass burning and secondary organic aerosol. Above the
ocean, fair agreement was obtained assuming an average hygroscopicity of
κ∼0.2 (deviations ≲ 16 %) and further
improvement was achieved assuming different hygroscopicities for Aitken and
accumulation mode particles (κAit=0.8, κacc=0.2; deviations ≲ 10 %), which may reflect
secondary marine sulfate particles. Our results indicate that Aitken mode
particles and their hygroscopicity can be important for droplet formation at
low pollution levels and high updraft velocities in tropical convective
clouds.

Atmospheric chemistry and physics, 2021-12, Vol.21 (23), p.17513-17528

Cloud droplet formation at the base of tropical convective clouds: closure between modeling and measurement results of ACRIDICON–CHUVA

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Jean Garling - personal papers, 1897-1998, together with associated papers, 1823-1998

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Series 1: Frederick Rose General Correspondence, [ca. 1930]-1991

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Automated Mapping of Convective Clouds (AMCC) Thermodynamical, Microphysical, and CCN Properties from SNPP/VIIRS Satellite Data

Export this record

Export record to excel

Cloud droplet formation at the base of tropical convective clouds: closure between modeling and measurement results of ACRIDICON–CHUVA

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