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Proceedings Paper

Relationship between cloud base height retrieved from lidar and downward longwave irradiance
Author(s): Kyohei Yamada; Tadahiro Hayasaka; Nobuo Sugimoto
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Paper Abstract

Downward longwave radiation is a key process to understand the climate change, energy budget, and water cycle at the earth’s surface. Cloud is a dominant factor to determine the intensity of longwave radiation. It is widely known that cloud cover and cloud base height (CBH) have strong effects on the downward longwave radiation, however there are not so many studies regarding the quantitative evaluation of relationship between cloud properties and downward longwave radiation. The intent of the present study is to quantify the impact of cloud property on the downward longwave irradiance (DLI). We used the data obtained with CGR-4 pyrgeometer at Tateno, Japan for the period from January 2002 to December 2011. Cloud radiative contribution fraction (CRC) is evaluated with a ratio of the difference of DLI between observation under cloudy sky without precipitation and calculation assumed clear-sky condition to the observed DLI. The difference between calculation and observation is -4.60±3.00 W/m2, and the calculation method reproduced to observation. Cloud is classified into three types by CBH, low (CBH<2000 m), middle (2000≥CBH<5000 m), and high (CBH≥5000 m). In the results, CRC is almost proportional and inverse proportional to cloud cover (CC) and CBH in the average, respectively. However, CRC for low cloud shows proportion to CBH because existence of low altitude cloud is related to large precipitable water (PW).

Paper Details

Date Published: 8 November 2012
PDF: 6 pages
Proc. SPIE 8523, Remote Sensing of the Atmosphere, Clouds, and Precipitation IV, 85231Q (8 November 2012); doi: 10.1117/12.977270
Show Author Affiliations
Kyohei Yamada, Tohoku Univ. (Japan)
Tadahiro Hayasaka, Tohoku Univ. (Japan)
Nobuo Sugimoto, National Institute for Environmental Studies (Japan)

Published in SPIE Proceedings Vol. 8523:
Remote Sensing of the Atmosphere, Clouds, and Precipitation IV
Tadahiro Hayasaka; Kenji Nakamura; Eastwood Im, Editor(s)

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