著者

YUMIMOTO Keiya TANAKA Taichu Y. YOSHIDA Mayumi KIKUCHI Maki NAGAO Takashi M. MURAKAMI Hiroshi MAKI Takashi

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2018-035, (Released:2018-04-08)

被引用文献数

21

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The Japan Meteorological Agency (JMA) launched a next-generation geostationary meteorological satellite (GMS), Himawari-8, on October 7, 2014 and began its operation on July 7, 2015. The Advanced Himawari Imager (AHI) onboard Himawari-8 has 16 observational bands that enable the retrieval of full-disk maps of aerosol optical properties (AOPs), including aerosol optical thickness (AOT) and the Ångström exponent (AE) with unprecedented spatial and temporal resolution. In this study, we combined an aerosol transport model with the Himawari-8 AOT using the data assimilation method, and performed aerosol assimilation and forecasting experiments on smoke from an intensive wildfire that occurred over Siberia between May 15 and 18, 2016. To effectively utilize the high observational frequency of Himawari-8, we assimilated 1-h merged AOTs generated through the combination of six AOT snapshots taken over 10-min intervals, three times per day. The heavy smoke originating from the wildfire was transported eastward behind a low-pressure trough, and covered northern Japan from May 19 to 20. The southern part of the smoke plume then traveled westward, in a clockwise flow associated with high pressure. The forecast without assimilation reproduced the transport of the smoke to northern Japan; however, it underestimated AOT and the extinction coefficient compared with observed values, mainly due to errors in the emission inventory. Data assimilation with the Himawari-8 AOT compensated for the underestimation and successfully forecasted the unique C-shaped distribution of the smoke. In particular, the assimilation of the Himawari-8 AOT during May 18 greatly improved the forecast of the southern part of the smoke flow. Our results indicate that the inheritance of assimilation cycles and the assimilation of more recent observations led to better forecasting in this case of a continental smoke outflow.

著者

OKAMOTO Kozo ISHIBASHI Toshiyuki ISHII Shoken BARON Philippe GAMO Kyoka TANAKA Taichu Y. YAMASHITA Koji KUBOTA Takuji

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2018-024, (Released:2018-02-05)

被引用文献数

8

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This study evaluated the impact of a future space-borne Doppler wind lidar (DWL) on a super-low-altitude orbit using an observing system simulation experiment (OSSE) based on a sensitivity observing system experiment (SOSE) approach. Realistic atmospheric data, including wind and temperature, was provided as “pseudo-truth” (PT) to simulate DWL observations. Hourly aerosols and clouds that are consistent with PT winds were also created for the simulation. A full-scale lidar simulator, which is described in detail in the companion paper, simulated realistic line-of-sight wind measurements and observation quality information, such as signal-to-noise-ratio (SNR) and measurement error. Quality control (QC) procedures in the data assimilation system were developed to select high-quality DWL observations based on the averaged SNR from strong backscattering in the presence of aerosols or clouds. Also, DWL observation errors used in the assimilation were calculated using the measurement error estimated by the lidar simulator. The forecast impacts of DWL onboard polar- and tropical-orbiting satellites were assessed using the operational global data assimilation system. Data assimilation experiments were conducted in January and August in 2010 to assess overall impact and seasonal dependence. It is found that DWL on either polar- or tropical-orbiting satellites is overall beneficial for wind and temperature forecasts, with greater impacts for the January experiments. The relative forecast error reduction reaches almost 2 % in the tropics. An exception is a degradation in the southern hemisphere in August, suggesting a need to further refine observation error assignment and QC. A decisive conclusion cannot be drawn of the superiority of polar- or tropical-orbiting satellites due to their mixed impacts. This is probably related to the characteristics of error growth in the tropics. The limitations and possible underestimation of the DWL impacts, for example due to a simple observation error inflation setting, in the SOSE-OSSE are also discussed.

著者

KOSAKA Yuki KOBAYASHI Shinya HARADA Yayoi KOBAYASHI Chiaki NAOE Hiroaki YOSHIMOTO Koichi HARADA Masashi GOTO Naochika CHIBA Jotaro MIYAOKA Kengo SEKIGUCHI Ryohei DEUSHI Makoto KAMAHORI Hirotaka NAKAEGAWA Tosiyuki TANAKA Taichu Y. TOKUHIRO Takayuki SATO Yoshiaki MATSUSHITA Yasuhiro ONOGI Kazutoshi

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2024-004, (Released:2023-11-02)

被引用文献数

4

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The Japan Meteorological Agency (JMA) has developed the third Japanese global atmospheric reanalysis, the Japanese Reanalysis for Three Quarters of a Century (JRA-3Q). The objective of JRA-3Q is to improve quality in terms of issues identified in the previous Japanese 55-year Reanalysis (JRA-55) and to extend the reanalysis period further into the past. JRA-3Q is based on the TL479 version of the JMA global Numerical Weather Prediction (NWP) system as of December 2018 and uses results of developments in the operational NWP system, boundary conditions, and forcing fields achieved at JMA since JRA-55. It covers the period from September 1947, when Typhoon Kathleen brought severe flood damage to Japan, and uses rescued historical observations to extend its analyses backwards in time about 10 years earlier than JRA-55. This paper describes the data assimilation system, forecast model, observations, boundary conditions, and forcing fields used to produce JRA-3Q as well as the basic characteristics of the JRA-3Q product. The initial quality evaluation revealed major improvements from JRA-55 in the global energy budget and representation of tropical cyclones (TCs). One of the major problems in JRA-55—global energy imbalance with excess upward net energy flux at the top of the atmosphere and at the surface—has been significantly reduced in JRA-3Q. Another problem—a trend of artificial weakening of TCs—has been resolved through the use of a method that generates TC bogus based on the JMA operational system. There remain several problems such that volcanic-induced stratospheric warming is smaller than expected. This paper discusses the causes of such problems and possible solutions in future reanalyses.