- 著者
- PUTRI Nurfiena Sagita IWABUCHI Hironobu HAYASAKA Tadahiro
- 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.2018-020, (Released:2018-01-23)
- 被引用文献数
- 12
Two case studies of Mesoscale Convective System (MCS) in Indonesian region were conducted by applying an improved GTG tracking algorithm and ICAS algorithm to Himawari-8 AHI infrared data. The first case over Java Island showed a land-originating MCS in the boreal winter, which coincided with a wet phase of Madden-Julian Oscillation (MJO) over the Maritime Continent. The second case showed the evolution of MCS under the influence of a strong vertical wind shear during the boreal summer. The cloud top height (CTH) of deep convective part in the first case was larger than that in the second case, while the temporal evolution of CTH was similar between two cases. For the anvil part, the median CTH of the second case was relatively stable at around 13 km, while that of the first case showed a considerable temporal variation ranging from 14 to 16 km. The cloud-particle effective radius (CER) of anvil increased after the period of maximum deep convective CTH in both cases, although the CER was slightly larger in the second case than in the first case. These differences in cloud properties between two cases were attributable to the background wind profiles.
- 著者
- NUR'UTAMI Murni Ngestu HAYASAKA Tadahiro
- 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.2022-004, (Released:2021-10-04)
The interannual and interdecadal variabilities of Indonesian rainfall in dry seasons (June–November) are investigated by using rainfall data from the Climate Research Unit (CRU) from 1939 to 2016, and from the Global Precipitation Climatology Project (GPCP) from 1979 to 2016. The first principal component (PC1) of both the CRU and GPCP data shows that the canonical El Niño-Southern Oscillation (ENSO), ENSO Modoki, and Indian Ocean Dipole (IOD) are major climate modes influencing the interannual variability of rainfall in Indonesia, and the Interdecadal Pacific Oscillation (IPO) is the major decadal phenomenon affecting the decadal variability of the rainfall. Furthermore, the IPO modulates the influence of IOD on Indonesian rainfall, with a weaker influence during the positive IPO phase during 1979-1997 and a stronger influence during the negative IPO phases during 1939-1978 and 1998-2016. The dependency of Indonesian rainfall response to the canonical ENSO and ENSO Modoki on IPO phases is not significant, although the response to the ENSO Modoki (canonical ENSO) becomes significant (less significant) in the negative IPO phase during 1998-2016 compared with earlier periods.
- 著者
- KHATRI Pradeep HAYASAKA Tadahiro IWABUCHI Hironobu TAKAMURA Tamio IRIE Hitoshi NAKAJIMA Takashi Y.
- 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.2018-036, (Released:2018-04-09)
- 被引用文献数
- 9
The present study implements long-term surface observed radiation data (pyranometer observed global flux and sky radiometer observed spectral zenith transmittance data) of multiple SKYNET sites to validate water cloud optical properties (cloud optical depth COD and effective radius Re) observed from space by MODIS onboard TERRA and AQUA satellites and AHI onboard Himawari-8 satellite. Despite some degrees of differences in COD and Re between MODIS and AHI, they both showed common features when validated using surface based global flux data as well as cloud properties retrieved from sky radiometer observed zenith transmittance data. In general, CODs from both satellite sensors are found to overestimated when clouds are optically thin. Among a number of factors (spatial and temporal variations of cloud, sensor and solar zenith angles), the solar zenith angle (SZA) is found to have an impact on COD difference between reflectance based satellite sensor and transmittance based sky radiometer. The Re values from the sky radiometer and satellite sensor are generally poorly correlated. The difference in Re between the sky radiometer and satellite sensor is negatively correlated with COD difference between them, which is likely due to the inherent influence of Re retrieval precision on COD retrieval and vice versa in transmittance based sky radiometer.
- 著者
- HAYASAKA Tadahiro
- 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.2016-024, (Released:2016-07-13)
- 被引用文献数
- 9
We reviewed the long-term trends and inter-annual variations in surface shortwave irradiance in China and Japan. Pyranometer observations indicated a decrease followed by an increase in shortwave irradiance in China and Japan during the period from the 1960s to 2000s, while obvious long-term trends were not found from satellite observations after 1983. In China, surface shortwave irradiance decreased from 1961 to around 1990, but then began to increase. In Japan, on the other hand, the decreasing trend stopped in the 1960s, with little inter-annual variation during the 1970s and 1980s, and an increase that began around 1990. The causes of the difference in shortwave irradiance trends between China and Japan were ascribed to an increase in light-absorbing aerosols in China since the 1960s and a decrease in absorbing aerosols in Japan since 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 aerosol could have a direct effect 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 phase of the minimum period differed slightly between the two regions. An increase in anthropogenic aerosol was responsible for the variation in shortwave irradiance through the direct radiative effect of aerosol in the polluted area, while an indirect radiative effect, i.e., changes in cloud cover due to an increase in cloud condensation nuclei, dominated in pristine areas. The effect 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.