If you have any problems related to the accessibility of any content (or if you want to request that a specific publication be accessible), please contact (firstname.lastname@example.org). We will work to respond to each request in as timely a manner as possible.
Measurement comparisons towards improving the understanding of aerosol-cloud processing
AuthorNoble, Stephen R.
AdvisorHudson, James G
StatisticsView Usage Statistics
Cloud processing of aerosol is an aerosol-cloud interaction that is not heavily researched but could have implications on climate. The three types of cloud processing are chemical processing, collision and coalescence processing, and Brownian capture of interstitial particles. All types improve cloud condensation nuclei (CCN) in size or hygroscopicity (κ). These improved CCN affect subsequent clouds. This dissertation focuses on measurement comparisons to improve our observations and understanding of aerosol-cloud processing.Particle size distributions measured at the continental Southern Great Plains (SGP) site were compared with ground based measurements of cloud fraction (CF) and cloud base altitude (CBA). Particle size distributions were described by a new objective shape parameter to define bimodality rather than an old subjective one. Cloudy conditions at SGP were found to be correlated with lagged shape parameter. Horizontal wind speed and regional CF explained 42%+ of this lag time. Many of these surface particle size distributions were influenced by aerosol-cloud processing. Thus, cloud processing may be more widespread with more implications than previously thought.Particle size distributions measured during two aircraft field campaigns (MArine Stratus/stratocumulus Experiment; MASE; and Ice in Cloud Experiment-Tropical; ICE-T) were compared to CCN distributions. Tuning particle size to critical supersaturation revealed hygroscopicity expressed as κ when the distributions were overlain. Distributions near cumulus clouds (ICE-T) had a higher frequency of the same κs (48% in ICE-T to 42% in MASE) between the accumulation (processed) and Aitken (unprocessed) modes. This suggested physical processing domination in ICE-T. More MASE (stratus cloud) κ differences between modes pointed to chemical cloud processing. Chemistry measurements made in MASE showed increases in sulfates and nitrates with distributions that were more processed. This supported chemical cloud processing in MASE. This new method to determine κ provides the needed information without interrupting ambient measurements. MODIS derived cloud optical thickness (COT), cloud liquid water path (LWP), and cloud effective radius (re) were compared to the same in situ derived variables from cloud probe measurements of two stratus/stratocumulus cloud campaigns (MASE and Physics Of Stratocumulus Tops; POST). In situ data were from complete vertical cloud penetrations, while MODIS data were from pixels along the aircraft penetration path. Comparisons were well correlated except that MODIS LWP (14-36%) and re (20-30%) were biased high. The LWP bias was from re bias and was not improved by using the vertically stratified assumption. MODIS re bias was almost removed when compared to cloud top maximum in situ re, but, that does not describe re for the full depth of the cloud. COT is validated by in situ COT. High correlations suggest that MODIS variables are useful in self-comparisons such as gradient changes in stratus cloud re during aerosol-cloud processing.
Showing items related by title, author, creator and subject.
.Gao, Lan (2018)Cumulus clouds are generally optically thick and shallow, exerting a net cooling impact on the climate system. Changes in atmospheric aerosol conditions, especially aerosol concentration increased by anthropogenic activity, ...
Calculation of Cloud Reflectivity in Rain In Cloud over the Ocean: A Study of the First Aerosol Indirect Effect Noble, Stephen R. (2009)The first indirect aerosol effect creates large uncertainty in climate change. Hudson et al. (2009) showed that more cloud droplets exist when there are more cloud condensation nuclei. By increasing cloud droplet ...
.Al Kiswani, Jalal Hasan Ahmed (2019)The development of modern software applications requires the adoption of cutting-edge techniques, technologies, frameworks, tools, and infrastructure. Even though there are many options to choose in every category, the ...