The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / Entrance Hall (1st floor) , National Institute of Polar Researc

Fumihisa Kobayashi

Makoto Kuji

Masahiro Hori

Naho Nakatsuji

Naoyuki Kurita

Sara Hirose

National Institute of Polar Research Repository

Characteristics of cloud fraction from whole-sky camera and ceilometer observations onboard R/VShirase during JARE 60Makoto KUJI1, Sara Hirose1, Naho Nakatsuji1, Masahiro Hori2, Naoyuki Kurita3 and Fumihisa Kobayashi41Nara Women’s University2Earth Observation Research Center, Japan Aerospace Exploration Agency3Institute for Space-Earth Environmental Research, Nagoya University4Graduate School of Science and Technology, Hirosaki UniversityCloud has opposite effects on the earth climate system: warming and cooling. Their magnitudes depend on cloud fraction,height, and so on. They influence the radiation balance on the earth and they are one of the greatest error sources for the climateprediction [IPCC, 2013]. Nevertheless, it is not easy to make a detailed observation due to their spatial and temporal variability.Furthermore, we do not have enough observation sites over ocean which covers approximately 70% of the earth surface. It is,therefore, important to elucidate their behavior. Thus, we make a periodical shipboard observation to investigate maritime cloudusing whole-sky camera, ceilometer and visual observations onboard R/V Shirase between Japan and Antarctica.Shipboard observations were carried out onboard R/V Shirase (AGB-5003) [Kuji et al., 2016]. The whole-sky camera systemmainly consists of a digital camera (Nikon D7000, Nikon Corporation) and a circular fisheye lens (4.5 mm F2.8 EX DC CircularFisheye HSM, SIGMA Corporation) to take a photo of a whole sky. The observation interval is 5 min. We have 66,529 imagesfrom 21 August 2018 to 11 April 2019 (JARE 60). We investigated the distribution of clouds over ocean by estimating cloudfraction from whole-sky camera images based on a cloud detection method [Yoshimura and Yamashita, 2013]. However, weanalyzed the whole-sky images over sea ice region as a function of solar height because sea surface albedo over sea ice regionsis very different from that over open ocean [Kuji et al., 2018]. The ceilometer is an instrument to determine cloud base heightsby measuring the return time of laser beam (Vaisala CL51). The observation interval is 36 s. We have 558,969 profiles from 21August 2018 to 11 April 2019 (JARE 60). We can obtain up to three cloud base height with the software built in the system.The cloud fraction with the ceilometer as defined as a frequency of cloud appearance, that is, the ratio of cloudy to total effectiveprofiles. In addition, we can use the cloud fraction by visual observation as one of the meteorological datasets. The observationinterval is 1 h. We have 3,267 cloud fractions from 10 November 2018 to 9 April 2019 (JARE 60).Figure 1 illustrates the temporal variation of the cloud fractions resulted from the ceilometer and visual observations during JARE60 from 2 December 2018 to 13 March 2019. It is found that the variation of cloud fractions is generally consistent. As a resultof the initial analysis, the correlation coefficient is very high of 0.84. 0 20 40 60 80 1002018/12/13 2018/12/27 2019/01/10 2019/01/24 2019/02/07 2019/02/21 2019/03/07Cloud fraction (%)Year/Month/DayJ60Figure 1: Temporal variation of daily-averaged cloud fractions during JARE 60 from 1 December 2018 to 13 March 2019. Solidand dashed lines correspond to the ceilometer and the visual observations, respectively.We are going to examine the characteristics of the cloud fraction estimated from the whole-sky camera on the ship tracks.Furthermore, we will make a validation study comparing the cloud fractions from R/V Shirase as well as satellite observations.AcknowledgmentsThe shipborne observation was conducted in cooperation with Japan Aerospace Exploration Agency (JAXA) and National Insti-tute of Polar Research. The authors are grateful to those who related to observations onboard R/V Shirase during JARE 55, 56,57, 58, 59 and 60. The authors are also grateful to Ms. Saori Yamano of Nara Women’s University, Japan, for her kind advices.ReferencesIntergovernmental Panel on Climate Change (IPCC2013), Climate Change 2013.Yoshimura M. and M. Yamashita, Contribution of Ground-Based Cloud Observation to Satellite-Based Cloud Discrimination, J.Environ. Sci. Eng. A, 2, 379-382, 2013.Kuji M., R. Fujimoto, M. Miyagawa, R. Funada, M. Hori, H. Kobayashi, S. Koga, J. Matsushita, and M. Shiobara, Cloudfractions estimated from shipboard whole-sky camera and ceilometer observations, Transactions of the Japan Society forAeronautical and Space Sciences, Aerospace Technology Japan, 14, 7-13, 2016.Kuji, M., A. Murasaki, M. Hori, M. Shiobara, 2018: Cloud Fractions Estimated from Shipboard Whole-Sky Camera andCeilometer Observations between East Asia and Antarctica. J. Meteor. Soc. Japan, 96, 201-214.

Characteristics of cloud fraction from whole-sky camera and ceilometer observations onboard R/V Shirase during JARE 60

https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=15764&item_no=1&attribute_id=16&file_no=1

Characteristics of cloud fraction from whole-sky camera and ceilometer observations onboard R/V Shirase during JARE 60

Abstract

Similar works

Full text

Available Versions

National Institute of Polar Research Repository