著者

Nurfiena Sagita PUTRI Tadahiro HAYASAKA Kim Dionne WHITEHALL

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

vol.95, no.6, pp.391-409, 2017 (Released:2017-11-14)

参考文献数

30

被引用文献数

11

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A mesoscale convective system (MCS) is organized thunderstorms with connected anvils, which has a significant impact on the global climate. By focusing on MCSs over the Maritime Continent of Indonesia, this study aims to gain a better understanding on the properties of the MCSs over the study area. The “Grab ‘em Tag ‘em Graph ‘em” (GTG) tracking algorithm is applied to hourly Multi-functional Transport Satellite-1R data for two years to observe the distribution of MCSs and the evolution of MCSs along their lifetime. The results of MCS identification by using GTG are combined with CloudSat data products to study the vertical structure of the MCSs at various MCS life stages: developing, mature, and dissipating. The distribution of MCSs over Indonesia has a seasonal variation and distinct diurnal cycle. The life stages of the observed MCSs are characterized by distinct cloud microphysics at each stage. In the developing stage, the upper level of the MCS raining region shows the presence of precipitating ice particles. As the MCS progresses to the mature stage, the proportion of the raining area becomes small and the intensity of rain is reduced, accompanied by increasing occurrence of small-sized ice particles at the upper level. In the dissipating stage, large hydrometeors no longer exist at the upper part of the raining region. Within the MCS anvils, the dissipating stage shows a more uniform distribution of ice-particle effective radius compared to that shown by the developing and mature stages. MCS characteristics over the land and ocean differ on the basis of the minimum brightness temperature, the equivalent radius, the maximum rain rate, and the rain fraction that varies along the MCS evolution.

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.

著者

Tadahiro HAYASAKA

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

vol.94, no.5, pp.393-414, 2016 (Released:2016-10-31)

参考文献数

111

被引用文献数

9

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We reviewed the long-term trends and inter-annual variations in the surface shortwave irradiance in China and Japan. Pyranometer observations revealed decreases followed by increases in the shortwave irradiance in China and Japan between the 1960s and 2000s, while obvious long-term trends were not evident in the satellite observations after 1983. In China, surface shortwave irradiance decreased from 1961 until around 1990, but then began to increase. In Japan, on the contrary, the decreasing trend stopped in the 1960s, with little inter-annual variation during the 1970s and 1980s, and an increase began around 1990. The causes of the differences between the shortwave irradiance trends in China and Japan were ascribed to an increase in light-absorbing aerosols in China that began in the 1960s and a decrease in absorbing aerosols in Japan that began in the late 1970s. Absorbing aerosols decrease both direct and diffuse radiation, while non-absorbing aerosols decrease direct radiation but increase diffuse radiation. Although these aerosol influences are generally found under clear sky conditions, absorbing aerosols could have direct effects even under cloudy sky conditions. The trends of surface shortwave irradiance in China and Japan are in line with the so-called global dimming and brightening dimming processes, although the phases of the minimum periods in the two regions slightly differed. An increase in anthropogenic aerosol was responsible for the variation in the shortwave irradiance through the direct radiative effect of aerosol in the polluted area, while indirect radiative effects, i.e., changes in cloud cover due to an increase in cloud condensation nuclei, dominated in pristine areas. The effects of other factors, such as variations in water vapor and natural aerosol levels, appear to be small compared to the effects of cloud and anthropogenic aerosols.

著者

Naoya Takahashi Tadahiro Hayasaka Hajime Okamoto

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.12, pp.91-95, 2016 (Released:2016-04-05)

参考文献数

34

被引用文献数

1

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We revealed the difference in the ice cloud microphysical properties of high clouds between the western Pacific (WP) and eastern Pacific (EP) regions, based on satellite retrievals. The effective particle radius (re) was analyzed by using active sensors on board the CloudSat and CALIPSO satellites. We focused on ice clouds, defined as clouds with cloud top temperatures of less than 0°C. These ice clouds are classified into five types defined by the cloud optical thickness (COT). Mean cloud top heights of high cloud in WP were higher than those in EP by about 2km. The re of optically thin clouds (0 < COT < 0.3) showed weak temperature dependency over both regions. For optically thick clouds (3 < COT), re increases with temperature (T). In the WP, re at lower temperatures (T < −40°C) is larger than that in the EP, whereas in the EP, re at higher temperatures (T > −40°C) is larger than that in the WP. The difference in re may be caused by differences in moisture convergence and upward motion.