著者

Hironobu IWABUCHI Nurfiena Sagita PUTRI Masanori SAITO Yuka TOKORO Miho SEKIGUCHI Ping YANG Bryan A. BAUM

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.96B, pp.27-42, 2018 (Released:2018-03-16)

参考文献数

35

被引用文献数

44

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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

Xinyue Wang Hironobu Iwabuchi Naoya Takahashi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.137-142, 2019 (Released:2019-06-27)

参考文献数

21

被引用文献数

1 2

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Using several cloud properties retrieved from the Himawari-8 satellite, combined with the best track storm center information, the temporal-spatial features of tropical cyclone (TC) diurnal pulses in 2015 Super Typhoon Atsani (T1516) are coherently depicted. To demonstrate the radially outward transition processes of the diurnal pulses from one cloud type to another, we divided high clouds into three types: opaque high cloud (OHC), cirrostratus (Cs), and cirrus (Ci). Two alternatively appeared peaks in cloud top height (CTH) within the storm central area and their corresponding outward pulses are identified. The first pulse covers a 24-hour period, it starts at ∼0500-0700 local solar time (LST), with a gradual transition from OHC to Cs, then ends in Ci at around 0400 LST. The second pulse lasts for half a day and limited within 1000 km from the storm center. When the first CTH pulse ends in OHC, Cs, and Ci, their cloud fractional coverage and the outward expansion of large cloud optical thickness also reach maximum accordingly.

著者

Pradeep Khatri Hiroaki Ooashi Hironobu Iwabuchi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.228-232, 2020 (Released:2020-12-05)

参考文献数

39

被引用文献数

5

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Aerosol effects on deep convective cloud (DCC) have been recognized as one of the complex subjects in climatic studies because of the difficulty in quantifying the sole effect of aerosols on DCC. The complexity further arises if the atmosphere has very strong temporal and spatial variations such as that of Indo-Pacific Warm Pool (IPWP) region. Considering the strong influence of IPWP region on global climate change and water circulation, we investigated aerosol effects on DCC over this region by using data of 2015-2016 El Niño and the 2017-2018 La Niña events. We developed a spectral analysis based framework to identify and decouple the influences of major external factors on aerosol-DCC relationship. We found that temporal variations of aerosols, clouds, and meteorology longer than 2 days' time scale can have larger influences than their diurnal and spatial variations on aerosol-DCC relationship. By removing the effects of those spatial and temporal variations of different scales, the study suggests that aerosols of IPWP region can affect DCC properties with time lags less than ∼5 hours and by increasing cloud-top height, cloud coverage, and DCC number concentration with the increase of aerosols.

著者

Pradeep Khatri Hiroaki Ooashi Hironobu Iwabuchi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2020-038, (Released:2020-10-22)

被引用文献数

5

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Aerosol effects on deep convective cloud (DCC) have been recognized as one of the complex subjects in climatic studies because of the difficulty in quantifying the sole effect of aerosols on DCC. The complexity further arises if the atmosphere has very strong temporal and spatial variations such as that of Indo-Pacific Warm Pool (IPWP) region. Considering the strong influence of IPWP region on global climate change and water circulation, we investigated aerosol effects on DCC over this region by using data of 2015-2016 El Niño and the 2017-2018 La Niña events. We developed a spectral analysis based framework to identify and decouple the influences of major external factors on aerosol-DCC relationship. We found that temporal variations of aerosols, clouds, and meteorology longer than 2 days' time scale can have larger influences than their diurnal and spatial variations on aerosol-DCC relationship. By removing the effects of those spatial and temporal variations of different scales, the study suggests that aerosols of IPWP region can affect DCC properties with time lags less than ∼5 hours and by increasing cloud-top height, cloud coverage, and DCC number concentration with the increase of aerosols.

著者

Alessandro Damiani Hitoshi Irie Tamio Takamura Rei Kudo Pradeep Khatri Hironobu Iwabuchi Ryosuke Masuda Takashi Nagao

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.198-204, 2019 (Released:2019-09-27)

参考文献数

39

被引用文献数

4

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We used observations recorded at Chiba University in November 2018 to examine the variability in cloud optical depth (COD) under overcast conditions. First, we conducted a careful evaluation of four COD datasets retrieved from three types of surface observations: i) zenith radiance recorded by two sky radiometers; ii) solar radiation data collected by a pyranometer; and iii) spatial distribution of radiance recorded using a sky camera system. Although the COD retrieved from the pyranometer (camera) slightly (moderately) overestimated the COD from zenith radiance, we found a satisfactory correlation among all surface estimates. This result suggests the efficacy of both pyranometer- and camera-based approaches and supports their broader use when dedicated cloud observations are not available. We then assessed satellite-based COD estimates retrieved from the recently launched Advanced Himawari Imager (AHI) aboard Himawari-8 (H-8) and Second-generation Global Imager (SGLI) on the Global Change Observation Mission for Climate (GCOM-C). Overall, we found good agreement between ground and satellite estimates; their correlation and root mean square error were virtually equivalent to values reported for co-located surface-based instruments. Nevertheless, the AHI-based COD was found to be slightly positively biased with respect to surface datasets.

著者

Shogo Sakai Hironobu Iwabuchi Feng Zhang

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.57-61, 2019 (Released:2019-03-16)

参考文献数

16

被引用文献数

1

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We have developed a rapid simplified algorithm to retrieve cloud optical thickness and cloud-top height from measurements of the infrared split-window bands of Himawari-8. The method is based on a rapid calculation model for clear-sky brightness temperatures and empirical equations for cloud, for which the coefficients are determined by a fit to a more rigorous radiative-transfer model. This method can be applied regardless of regions excluding the polar regions and season by taking into account the temperature, humidity, sea surface temperature, and surface emissivity. In this study, we have demonstrated that this method captures well the diurnal cycle of cloud amounts of different cloud types in the warm-pool region around Indonesia. With an accelerated retrieval process by a factor of around 1,000 compared with the the physics-based retrieval, our rapid cloud retrieval algorithm yielded cloud amounts that agree quantitatively with those from a more rigorous, physics-based cloud retrieval method.

著者

Miho SEKIGUCHI Hironobu IWABUCHI Takashi M. NAGAO Teruyuki NAKAJIMA

出版者

Meteorological Society of Japan

雑誌

Journal of the Meteorological Society of Japan. Ser. II (ISSN:00261165)

巻号頁・発行日

pp.2018-007, (Released:2017-12-08)

被引用文献数

2

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We developed an atmospheric gas absorption table for the Advanced Himawari Imager (AHI) based on the correlated k-distribution (CKD) method with the optimization method, which was used to determine quadrature weights and abscissas. We incorporated the table and band information of the AHI into a multi-purpose atmospheric radiative transfer package, Rstar. We updated the package so that users could easily specify the satellite and band number. Use of this update made it possible for the optimized CKD method to carry out calculations rapidly and accurately. Rstar is easy for beginners to use and facilitates comparison of results. Cloud retrieval tests using different numbers of quadrature points showed that cloud retrievals could be significantly affected by the accuracy of the CKD model.

著者

Kyohei Yamada Tadahiro Hayasaka Hironobu Iwabuchi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.8, pp.94-97, 2012 (Released:2012-08-21)

参考文献数

20

被引用文献数

4 4

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To estimate contributions of water vapor (WV), carbon dioxide (CO2), and clouds to longwave radiation, surface downward longwave irradiance (DLI) was evaluated by comparing observations with values calculated using data from vertical profiles of WV and clouds obtained from radiosonde observations at five Baseline Surface Radiation Network (BSRN) sites. The observed DLI was reproduced by calculation with an accuracy of 3.9 ± 4.4 W m-2 for clear-sky conditions at all sites, but the accuracy was -7.7 ± 8.6 W m-2 for overcast conditions. The individual contributions of WV, CO2, and clouds to DLI were evaluated by removing these factors one by one from the normal condition including all of the factors (removal method) and by removing all factors except for one particular factor (addition method). The results indicate that the contributions of WV and clouds are relatively large, whereas the contribution of CO2 is relatively small.