Sign up & Download
Sign in

Characteristics of aerosol and cloud particle size distributions in the tropical tropopause layer measured with optical particle counter and lidar

by S. Iwasaki, K. Maruyama, M. Hayashi, S.-Y. Ogino, H. Ishimoto, Y. Tachibana, A. Shimizu, I. Matsui, N. Sugimoto, K. Yamashita, K. Saga, K. Iwamoto, Y. Kamiakito, A. Chabangborn, B. Thana, M. Hashizume, T. Koike, T. Oki show all authors
Atmospheric Chemistry and Physics ()

Abstract

Abstract. An optical particle counter (OPC) is used in conjunction with lidar measurements to examine the characteristics of the particle size distribution in cirrus cloud in the tropical tropopause layer (TTL) over Thailand where the TTL is defined as the height at which temperature is lower than -75C in this paper. Of 11 OPC launches, cirrus cloud was detected at 10-15 km high on 7 occasions, cirrus was detected in the TTL in 6 cases, and simultaneous OPC and lidar measurements were made on two occasions. Comparison of lidar and OPC measurements reveal that the cloud heights of cirrus in the TTL varies by several hundred meters over distances of tens kilometers; hence the height is not always horizontally uniform. The mode radii of particles constituting the clouds are estimated by lidar and OPC measurements to be less than approximately 10mm. The regression lines of the particle size distribution with and without cirrus cloud exhibit similar features at equivalent radii of <0.8mm. Enhancement in the integrated number concentration at radii greater than 0.8mm indicates that liquid particles tend to be frozen at a radius of 0.8mm, with cirrus clouds above 10 km exhibiting similar features. On the other hand, enhancement in the particle size distribution at radii greater than 0.9mm and a peak at around 0.8mm in the ratio of the standard deviation of count values to that of the Poisson distribution of the averaged count values are common features of cirrus clouds in the TTL, where the ratio shows the vertical homogeneity of the particle number. These typical features suggest that the transition from liquid, sulfuric acid aerosol, to ice is more observable in the TTL and the timing of freezing may vary with height in the TTL.

Cite this document (BETA)

Readership Statistics

7 Readers on Mendeley
by Discipline
 
 
 
by Academic Status
 
43% Ph.D. Student
 
29% Researcher (at an Academic Institution)
 
14% Student (Bachelor)
by Country
 
14% United States

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Already have an account? Sign in