- 著者
- IWABUCHI Hironobu PUTRI Nurfiena Sagita SAITO Masanori TOKORO Yuka SEKIGUCHI Miho YANG Ping BAUM Bryan A.
- 出版者
- (公社)日本気象学会
- 雑誌
- 気象集誌. 第2輯 (ISSN:00261165)
- 巻号頁・発行日
- pp.2018-001, (Released:2017-09-15)
- 被引用文献数
- 44
An algorithm for retrieving the macroscopic, physical and optical properties of clouds from thermal infrared measurements is applied to the Himawari-8 multiband observations. A sensitivity study demonstrates that the addition of the single CO2 band of Himawari-8 is effective for the estimation of cloud top height. For validation, retrieved cloud properties are compared systematically with collocated active remote sensing counterparts with small time lags. While retrievals agree reasonably for single-layer clouds, multilayer cloud systems with optically thin upper clouds overlying lower clouds are the major source of error in the present algorithm. Validation of cloud products is critical for identifying the characteristics, advantages and limitation of each product and should be continued in the future. As an application example, data are analyzed for eight days in the vicinity of the New Guinea to study the diurnal cycle of the cloud system. The present cloud property analysis investigates cloud evolution through separation of different cloud types and reveals typical features of diurnal cycles related to the topography. Over land, middle clouds increase from 0900 to 1200 local solar time (LST), deep convective clouds develop rapidly during 1200–1700 LST with a subsequent increase in cirrus and cirrostratus cloud amounts. Over the ocean near coastlines, a broad peak of convective cloud fraction is seen in the early morning. The present study demonstrates the utility of frequent observations by Himawari-8 for life cycle study of cloud systems, owing to the ability to capture their continuous temporal variations.
- 著者
- 齊藤 雅典 岩渕 弘信 Yang Ping Tang Guanglin King Michael Sekiguchi Miho
- 出版者
- 日本地球惑星科学連合
- 雑誌
- JpGU-AGU Joint Meeting 2017
- 巻号頁・発行日
- 2017-03-10
Microphysical properties and ice particle morphology of cirrus clouds are important for estimating the radiative forcing associated with these clouds. Many satellite measurements allow us to estimate the cloud optical thickness (COT) and cloud-particle effective radius (CER) of cirrus clouds over the globe via multiple retrieval methods such as the bi-spectral method using visible and near-infrared cloud reflectivities, the split-window method using thermal infrared brightness temperatures and the unconstrained method using lidar signals. However, comparisons among these retrievals exhibit discrepancies in some cases due to particular error sources for each method. In addition, methods to infer ice particle morphology of clouds from satellite measurements are quite limited. To tackle these current problems, we develop an optimal estimation based algorithm to infer cirrus COT, CER, plate fraction including horizontally oriented plates (HOPs) and the degree of surface roughness from the Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and the Infrared Imaging Radiometer (IIR) on the Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) platform. A simple but realistic ice particle model is used, and the bulk optical properties are computed using state-of-the-art light-scattering computational capabilities. A rigorous estimation of the uncertainties related to the surface properties, atmospheric gases and cloud heterogeneity is performed. A one-month global analysis for April 2007 with a focus on HOPs shows that the HOP fraction has significant temperature dependence and therefore latitudinal variation. Ice particles containing many HOPs have small lidar ratio due to strong backscattering. The lidar ratio of cirrus clouds has a negative correlation with the temperature where the cloud temperature is warmer than −40℃, for which the median HOP fraction is larger than 0.01%.