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Condensation nuclei (CN) and ultrafine CN in the free troposphere to 12 km: A case study over the Jungfraujoch High‐Alpine Research Station
Author(s) -
Nyeki S.,
Kalberer M.,
Lugauer M.,
Weingartner E.,
Petzold A.,
Schröder F.,
Colbeck I.,
Baltensperger U.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900473
Subject(s) - troposphere , atmospheric sciences , altitude (triangle) , humidity , relative humidity , condensation , atmosphere (unit) , environmental science , physics , meteorology , geometry , mathematics
Condensation nuclei (CN) were measured in the free troposphere (FT) above the Jungfraujoch (JFJ) high‐alpine research station (3454 m; Switzerland) from 4.5 to 12 km asl in a case study on July 30, 1997. Vertical profiles of CN concentration for d ≥ 5 nm ( N ≥5 ), d ≥ 15 nm ( N ≥15 15) were measured, and indicated that ultrafine CN (UCN; 5 ≤ d ≤ 15 nm; N 5‐15 ) exhibited a distinct increase with altitude. Some evidence for near‐constant values of d(logCN)/dz within discrete layers was found, which generally coincided with different airmasses as delineated by changes in the lapse rate dθ/dz at ∼ 5.5, 6.4, 9.0 and 10.6 km asl. In addition, CN concentration was mapped over a 40 × 75 km horizontal domain at 8.0 km asl centered above the JFJ. A pronounced variation in N ≥5 , N ≥15 and specific humidity, but not in UCN, exhibited quasi‐stationary 2‐D features and was attributed to the chance encounter of a mountain wave. The case study provides further evidence that the upper FT may be a source of new particles.