NASA Logo, External Link
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed AddThis share icon
 

Record Details

Record 1 of 10080
Physical and Optical/Radiative Characteristics of Aerosol and Cloud Particles in Tropical Cirrus: Importance in Radiation Balance
Author and Affiliation:
Pueschel, R. F.(NASA Ames Research Center, Moffett Field, CA United States)
Howard, S. D.(Synernet Corp., Fremont, CA United States)
Foster, T. C.(California Polytechnic State Univ., San Luis Obispo, CA United States)
Hallett, J.(Desert Research Inst., Reno, NV United States)
Arnott, W. P.(Desert Research Inst., Reno, NV United States)
Condon, Estelle P. [Technical Monitor]
Abstract: Whether cirrus clouds heat or cool the Earth-atmosphere system depends on the relative importance of the cloud shortwave albedo effect and the cloud thermal greenhouse effect. Both are determined by the distribution of ice condensate with cloud particle size. The microphysics instrument package flown aboard the NASA DC-8 in TOGA/COARE included an ice crystal replicator, a 2D Greyscale Cloud Particle Probe and a Forward Scattering Spectrometer Aerosol Probe. In combination, the electro-optical instruments permitted particle size measurements between 0.5 micrometer and 2.6 millimeter diameter. Ice crystal replicas were used to validate signals from the electrooptical instruments. Both optical and scanning electron microscopy were utilized to analyze aerosol and ice particle replicas between 0.1 micrometer and several 100 micrometer diameter. In first approximation, the combined aerosol-cloud particle spectrum in several clouds followed a power law N alpha D(sup -2.5). Thus, large cloud particles carried most of the condensate mass, while small cloud and aerosol particles determined the surface area. The mechanism of formation of small particles is growth of (hygroscopic, possibly ocean-derived) aerosol particles along the Kohler curves. The concentration of small particles is higher and less variable in space and time, and their tropospheric residence time is longer, than those of large cloud particles because of lower sedimentation velocities. Small particles shift effective cloud particle radii to sizes much smaller than the mean diameter of the cloud particles. This causes an increase in shortwave reflectivity and IR emissivity, and a decrease in transmissivity. Occasionally, the cloud reflectivity increased with altitude (decreasing temperature) stronger than did cloud emissivity, yielding enhanced radiative cooling at higher altitudes. Thus, cirrus produced by deep convection in the tropics may be critical in controlling processes whereby energy from warm tropical oceans is injected to different levels in the atmosphere to subsequently influence not only tropical but mid-latitude climate.
Publication Date: Jan 01, 1996
Document ID:
20020041043
(Acquired May 03, 2002)
Subject Category: METEOROLOGY AND CLIMATOLOGY
Document Type: Preprint
Meeting Information: 14th International Conference on Nucleation and Atmospheric Aerosols; 26-30 Aug. 1996; Helsinki; Finland
Financial Sponsor: NASA Ames Research Center; Moffett Field, CA United States
Organization Source: NASA Ames Research Center; Moffett Field, CA United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: AEROSOLS; CIRRUS CLOUDS; OPTICAL PROPERTIES; CLOUD PHYSICS; ATMOSPHERIC RADIATION; CLIMATOLOGY; PARTICLE SIZE DISTRIBUTION; SCANNING ELECTRON MICROSCOPY; ALBEDO; ELECTRO-OPTICS; TEMPERATE REGIONS; EMISSIVITY; EARTH ATMOSPHERE
Availability Source: Other Sources
Availability Notes: Abstract Only
› Back to Top
Find Similar Records
NASA Logo, External Link
NASA Official: Gerald Steeman
Site Curator: STI Program
Last Modified: August 22, 2011
Contact Us