A Caltech Library Service

Intensive studies of Sierra Nevada cloudwater chemistry and its relationship to precursor aerosol and gas concentrations

Collett, Jeffrey L., Jr. and Daube, Bruce C., Jr. and Gunz, Dieter and Hoffmann, Michael R. (1990) Intensive studies of Sierra Nevada cloudwater chemistry and its relationship to precursor aerosol and gas concentrations. Atmospheric Environment Part A-General Topics, 24 (7). pp. 1741-1757. ISSN 0960-1686. doi:10.1016/0960-1686(90)90507-J.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


Measurements of inorganic aerosol and gas phase species are presented for three sites in central California during a 4 day period in April 1988. The measurement sites were located along an east-west transect at Visalia, Ash Mountain, and Lower Kaweah, with elevations of 90, 550 and 1900 m, respectively. Aerosol compositions were nearly neutral at all locations, however large concentrations of NH_3 at Visalia contributed significant excess alkalinity to the air mass sampled there. Concentrations of all major species were observed to decrease with elevation during most of the sampling periods. Concentrations at the upper two sites exhibited diurnal fluctuations, with peaks in the late afternoon, consistent with the transport of pollutants from San Joaquin Valley sources by daytime upslope winds. Concentrations of most of these species reached a maximum at the elevated sites on 28 April, as a weak cold front approached, reducing the atmospheric stability over the valley floor. Concentrations at Visalia on this day were somewhat lower than those observed earlier in the week. Clouds intercepting the mountain slopes on 28 April were sampled at two locations. The coudwater pH at both sites was observed to fall throughout the event, dropping as low as 4.34. Precursor concentrations of aerosol NO_3^−, SO_4^(2-) and NH_4^+, and gas phase HNO_3 and NH_3, were sufficient to account for the observed cloudwater loadings of NO_3^−, SO_4^(2-) and NH_4^+. In-cloud measurements made near the cloud base indicated a considerable S(IV) oxidation potential in the form of H_2O_2, but only low S(IV) concentrations. Cloudwater concentrations of formic acid were approximately three times acetic acid concentrations. Carbonyl concentrations were dominated by formaldehyde and glyoxal.

Item Type:Article
Related URLs:
URLURL TypeDescription
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 1990 Pergamon Press. First received 5 August 1989 and in final form 8 December 1989. We are grateful to the National Park Service, particularly the research staff at Sequoia National Park, for granting us access to sites within the Park. We gratefully acknowledge the California Air Resources Board for providing access to the sampling site in Visalia, for supplying meteorological data, and for providing financial support for this project (CARB contract # A6-185-32).
Funding AgencyGrant Number
California Air Resources Board (CARB)A6-185-32
Subject Keywords:Aerosol, aerosol scavenging, aerosol-gas equilibrium, ammonia, ammonium, California, cloudwater chemistry, hydrogen peroxide, nitrate, nitric acid, organic acids, organic carbonyl compounds, Sequoia National Park, Sierra Nevada, sulfate, sulfite
Issue or Number:7
Record Number:CaltechAUTHORS:20150813-105953574
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59486
Deposited By: Ruth Sustaita
Deposited On:14 Aug 2015 00:24
Last Modified:10 Nov 2021 22:21

Repository Staff Only: item control page