著者

Hideo Shiogama Noriko N. Ishizaki Naota Hanasaki Kiyoshi Takahashi Seita Emori Rui Ito Toshiyuki Nakaegawa Izuru Takayabu Yasuaki Hijioka Yukari N. Takayabu Ryosuke Shibuya

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.57-62, 2021 (Released:2021-04-03)

参考文献数

20

被引用文献数

1 16

---

Climate change impact assessment studies often use future projections of only a few global climate models (GCMs) due to limited research resources. Here we develop a novel method to select a small subset of GCMs that widely capture the uncertainty range of large ensemble. By applying this method, we select a subset of five GCM projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) ensemble for impact and adaptation studies in Japan. At first, we omit GCMs whose global warming projections have been evaluated to be overestimated in the recent literature. Then, we select a subset of five GCMs that widely captures the uncertainty ranges for 8 climate variables and have good performances in present-climate simulations. These selected GCM simulations will be used to provide better climate scenarios for impact and adaptation studies than those in the previous impact assessment project.

著者

Qoosaku Moteki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15A, pp.37-42, 2019 (Released:2019-07-10)

参考文献数

21

被引用文献数

13

---

Heavy rain in western Japan was broadly induced by the stagnation of the Baiu front during 5-7 July 2018. This study hypothesizes that cold air advection over the Sea of Japan intensified by Typhoon Prapiroon (Typhoon No. 7) was one of the triggering factors for the formation process of the Baiu front over western Japan. Typhoon Prapiroon passed over the Sea of Japan on 4 July and became extratropical at approximately 40°N on 5 July. During its passage, the strong southward pressure gradient force to the north of Typhoon Prapiroon broke down the convergence line of the Baiu front that remained at approximately 45°N before 4 July and thick cold air from the Okhotsk High flowed over the Sea of Japan. The Okhotsk High expanded toward the Sea of Japan and enhanced cold air advection to the north of western Japan. As a result, the Baiu front was stationary at approximately 35°N after 5 July. In addition, the westerly jet in the east of an upper-level trough deepened along the typhoon track was associated with the adiabatic component of the ascending motion over the isentropic upslope and was suggested to contribute to the maintenance of Baiu frontal convection.

著者

Saori Nakashita Takeshi Enomoto

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17A, no.Special_Edition, pp.33-37, 2021 (Released:2021-04-20)

参考文献数

14

被引用文献数

2

---

The predictability of Typhoon Hagibis in October 2019 is examined with ensemble forecasts from four major operational numerical weather prediction centers. From six to four days before the landfall, the forecast from the Japan Meteorological Agency was the best among the four centers. However, the error increased sharply three days before the landfall. Consistent with the westward track error, a northwestward bias is found in the environmental winds. The ensemble sensitivity analysis for the landing region indicates a large sensitivity to a ridge located to the southeast of the typhoon. The member with the largest track error has perturbations that act to weaken the ridge. A low-pressure disturbance to the southeast of the ridge is found to migrate westward faster than the member with the smallest track error. Therefore, the typhoon is advected westward by the easterlies associated with the low. These results indicate a significant influence of the tropical disturbance on the predictability of Hagibis.

著者

Seika Tanji Masaru Inatsu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.32-36, 2019 (Released:2019-02-13)

参考文献数

31

被引用文献数

2 4

---

Blowing snow potential is diagnosed for typical cases around Sapporo, Japan, as snow concentration and visibility based on dynamically downscaled data with 1-km resolution. The results are consistent with the blowing-snow records on time and place of traffic disruption, when the dynamical downscaling (DDS) reproduced wind speed well for a case. The diagnosis with mesoscale model analysis with 5-km resolution does not reproduce the blowing snow events in most area, however. Hence, the DDS potentially, not perfectly, adds the value to estimate blowing snow potential, despite a large scale-gap from an explicit representation of small-scale turbulence related to blowing snow. Sensitivity tests clarify that blowing snow requires strong wind and freezing temperature at the surface.

著者

Yu Someya Yukio Yoshida Shamil Maksyutov

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.157-161, 2020 (Released:2020-08-25)

参考文献数

33

被引用文献数

2

---

Although wetlands are the largest natural source of atmospheric methane, the amount and variability of methane emissions from wetlands still have large uncertainty. We investigated the local growth rate of the column-averaged methane dry air mole fraction (XCH4) in Siberia where wetlands are widely abundant using 11-year (2009-2019) Greenhouse gases Observing SATellite (GOSAT) data. While the mean growth rate during the summer from the GOSAT observations is 7.2 ppb yr−1 globally, that in West Siberia is 8.4 ppb yr−1. In particular, the growth rates in West Siberia after 2013 is much larger in July and August than in the other months. Moreover, the growth of XCH4 in West Siberia appears to larger than in the other boreal areas. These results imply that methane emissions from wetlands in West Siberia increased during the summer in recent several years.

著者

Narihiro Orikasa Masataka Murakami Takuya Tajiri Yuji Zaizen Taro Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.185-191, 2020 (Released:2020-10-17)

参考文献数

22

被引用文献数

2

---

Aircraft observations were conducted over the eastern mountainous areas of the United Arab Emirates (UAE) in September 2017 to characterize the microphysical properties of diurnal convective clouds. Aerosol particle and cloud condensation nuclei (CCN) measurements indicate that the air mass had a continental nature, resulting in high cloud droplet concentrations of 600-800 cm−3. Two case studies were undertaken to obtain the vertical profiles of hydrometeors up to the cloud top. The ice particle number concentrations in the updraft core were a few particles L−1, which is similar to the primary ice nucleating particle (INP) number concentrations estimated from immersion freezing of high concentration dust particles in the convectively mixed boundary layer. The ice particle number concentrations were several tens of particles L−1 outside the updraft core in the upper levels. INP measurements and the observed cloud microphysical structure suggest that drizzles, frozen via the immersion freezing nucleation of dust particles, formed graupel embryos and ice particles, with concentrations of one to two orders of magnitude greater than those of the primary INPs, which may be generated via secondary ice production and/or ice particle accumulation from primary ice nucleation in clouds with relatively warm cloud top temperatures (approximately −12°C).

著者

Shuhei Matsugishi Hiroaki Miura Tomoe Nasuno Masaki Satoh

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16A, no.Special_Edition, pp.12-18, 2020 (Released:2020-06-27)

参考文献数

38

被引用文献数

6

---

We show that a modification to the latent heat flux (LHF) formulation in Non-hydrostatic Icosahedral Atmospheric Model (NICAM) impacts the representation of a Madden–Julian oscillation (MJO) event during the Pre-Years of the Maritime Continent (Pre-YMC) field campaign in 2015. First, we compare the LHFs computed by the standard NICAM setting with those estimated from the ship observation during Pre-YMC. In this comparison, the NICAM LHF is smaller than observation in the low wind speed region and larger in the high wind speed region. Consequently, the MJO signal weakens when it passes over the Maritime Continent (MC). Next, sensitivity experiments are conducted with a modification to the threshold minimum wind speed in the bulk formula, to enhance the LHFs in the low wind speed region. With this modification, propagation of the MJO is better simulated over the MC, although a bias still remains without corrections in the high wind speed regions. This result indicates that increasing the LHF in the low wind speed region likely contributes to a more effective accumulation of moisture over the eastern MC region and consequently allows the MJO to pass over the MC in the model.

著者

Hideo Shiogama Rui Ito Yukiko Imada Toshiyuki Nakaegawa Nagio Hirota Noriko N. Ishizaki Kiyoshi Takahashi Izuru Takayabu Seita Emori

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.16, pp.75-79, 2020 (Released:2020-05-01)

参考文献数

22

被引用文献数

5

---

The ensemble average projections of the Coupled Model Inter-comparison Project Phase 5 (CMIP5) ensemble show future increases in shortwave radiation at the surface (SW) in Japan. We reveal that the Arctic Oscillation-like atmospheric circulation trends cause cloud cover decreases around Japan, leading to increases in the SW.In many cases, impact assessment studies use the outputs of only a few models due to limited research resources. We find that the four climate models used in the Japanese multisector impact assessment project, S-8, do not sufficiently capture the uncertainty ranges of the CMIP5 ensemble regarding the SW projections. Therefore, the impact assessments using the SW of these four models can be biased. We develop a novel method to select a better subset of models that are more widely distributed and are not biased, unlike the S-8 models.

著者

Nobuo Sugimoto Yoshitaka Jin Atsushi Shimizu Tomoaki Nishizawa Keiya Yumimoto

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.257-261, 2019 (Released:2019-12-26)

参考文献数

19

被引用文献数

1 7

---

Mineral dust transported from Africa and Middle East was observed with the Asian Dust and aerosol lidar observation Network (AD-Net). In March 2018, the dense Sahara dust, reported by mass media as that snow in Sochi, Russia stained into orange, was transported to Sapporo in 4 days from Sochi and observed by the lidar. In April 2015, dust from Middle East was transported to Nagasaki passing across the Taklamakan desert. Dust source areas and transport paths were studied with the global aerosol transport model MASINGAR mk-2 separately calculated for different dust sources regions. The results showed that dust from Sahara and Middle East was transported to East Asia and sometimes mixed with dust from the Gobi desert and the Taklamakan desert. The analysis of recent AD-Net data after 2015 showed such long-range transport cases were observed every year in March or April. The transport path often led over the Caspian Sea, Kazakhstan, and Russia. Sahara dust transported north and reached around the Black Sea was transported long range by strong westerly in springtime.

著者

Tetsuya Takemi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.125-131, 2019 (Released:2019-05-30)

参考文献数

32

被引用文献数

23

---

This study investigated the impacts of global warming on extreme rainfall produced by a slow-moving typhoon by conducting pseudo-global warming (PGW) experiments. We examined Typhoon Talas (2011) that caused long-lasting heavy rainfall exceeding 2000 mm over the Kii Peninsula. The experiments successfully captured the track and translation speed of the actual typhoon, which enabled to quantitatively assess the climate change impacts. The PGW experiments indicated that the extreme rainfall is intensified in the future climates than in the present climate. Especially, the higher extremes of the accumulated rainfall are projected to be more severe in the future climate scenario. The analysis on the environmental factors showed that the cases with increased precipitable water lead to the increases in rainfall in future climates, despite the stabilized atmospheric conditions. Among the PGW experiments, the most increased amount of rainfall was found not to be produced by the most intensified typhoon.

著者

Ryo Onishi Daisuke Sugiyama Keigo Matsuda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.178-182, 2019 (Released:2019-09-05)

参考文献数

21

被引用文献数

24

---

We propose a super-resolution (SR) simulation system that consists of a physics-based meteorological simulation and an SR method based on a deep convolutional neural network (CNN). The CNN is trained using pairs of high-resolution (HR) and low-resolution (LR) images created from meteorological simulation results for different resolutions so that it can map LR simulation images to HR ones. The proposed SR simulation system, which performs LR simulations, can provide HR prediction results in much shorter operating cycles than those required for corresponding HR simulation prediction system. We apply the SR simulation system to urban micrometeorology, which is strongly affected by buildings and human activity. Urban micrometeorology simulations that need to resolve urban buildings are computationally costly and thus cannot be used for operational real-time predictions even when run on supercomputers. We performed HR micrometeorology simulations on a supercomputer to obtain datasets for training the CNN in the SR method. It is shown that the proposed SR method can be used with a spatial scaling factor of 4 and that it outperforms conventional interpolation methods by a large margin. It is also shown that the proposed SR simulation system has the potential to be used for operational urban micrometeorology predictions.

著者

Akifumi Nishi Hiroyuki Kusaka Lidia Lazarova Vitanova Yuma Imai

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.132-136, 2019 (Released:2019-06-20)

参考文献数

27

被引用文献数

5

---

We quantitatively evaluated the contributions of foehn winds and the urban heat island (UHI) effect to an extreme high-temperature nocturnal event at Niigata city on 23-24 August 2018. During this event, southeasterly winds blew continually across the Niigata Plain and temperatures on the plain were higher than those in the windward region of the mountain range. Back-trajectory analysis and numerical simulations with and without topography showed that the southeasterly winds were foehn winds that caused precipitation and latent heating on the windward slope of the mountain range. The foehn winds and UHI contributed about 2.8°C and 1.9°C, respectively, to the extreme high-temperature of 31.0°C at 2100 JST in Niigata city. The combined impact of the foehn winds and the UHI at Niigata was about 4.0°C during the night. The contribution of the foehn winds was greater at around midnight, whereas that of the UHI was greater during the early night.

著者

Kentaro Araki Masataka Murakami Hiroshi Ishimoto Takuya Tajiri

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.11, pp.108-112, 2015 (Released:2015-08-11)

参考文献数

45

被引用文献数

7

---

Ground-based microwave radiometer (MWR) has been used for high-frequency retrievals of thermodynamic environments. However, raindrops on the radome of MWR and in the air cause errors in retrievals during precipitation events. Although a recent study has noted that off-zenith observations with neural networks (NN) reduce the retrieval errors, the effect of off-zenith observations with one-dimensional variational (1DVAR) technique, which is known to be more accurate than other methods, has not been studied. We developed a new 1DVAR technique that considers the effect of cloud liquid water. We statistically investigated the accuracy of vertical profiles of atmospheric temperature and water vapor retrieved by NN and 1DVAR techniques by using zenith and off-zenith observation at 15° elevation angle under no-rain and rainy conditions and compared them with results of radiosonde observations. The results showed that the 1DVAR technique outperforms NN and numerical model simulation in the estimation of thermodynamic profiles under no-rain conditions. The results also indicated that the error in retrieved profiles in the low-level troposphere can be reduced by the 1DVAR technique by using off-zenith observations even under rainy conditions with rainfall rate less than 1.0 mm h−1, especially when the environment cannot be accurately reproduced by a numerical model.

著者

Tomoro Yanase Tetsuya Takemi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.14, pp.116-120, 2018 (Released:2018-08-21)

参考文献数

29

被引用文献数

4

---

This study investigates the representation of the diurnal variation of cumulus convection in radiative-convective equilibrium states in an area of 200 km by 200 km without large-scale forcing by using a non-hydrostatic model with sub-kilometer horizontal resolutions. The experiment with the horizontal resolution of 200 m successfully reproduced the diurnal variability of the trimodal characteristics of cumulus convection. We demonstrated that the horizontal resolution dependence largely affects the trimodal structure of clouds and the characteristics of precipitation and its diurnal variation. With the coarse resolution of 1600 m, a signature of convective aggregation appeared and the diurnal variation of convection was not clearly seen. We further examined the mechanisms for the diurnal variation of cumulus convection by focusing on the temporal and vertical variations of radiative and latent heating anomalies. The diurnal variability of the static stability caused by both radiative and latent heating plays a role in characterizing the diurnal variation of the cumulus convection.

著者

Masatake E. Hori Jun Inoue Takashi Kikuchi Meiji Honda Yoshihiro Tachibana

出版者

(公社)日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.7, pp.25-28, 2011 (Released:2011-02-10)

参考文献数

12

被引用文献数

16 35

---

In the winter of 2009/2010, Japan and the East Asian region experienced a frequent occurrence of cold air outbreaks. Although the winter average temperature in the Japan main islands was slightly positive (+0.81°C for DJF average and +0.71°C for NDJFM average), repeated decline in temperature was notable throughout the season. One explanation for this abnormal winter season is the extremely negative condition of the Arctic Oscillation (AO) that persisted from December to mid-January. However, AO alone does not provide sufficient explanation for the cold air outbreak during November or its intraseasonal periodicity. A case study of the cold air outbreak that reached Japan on Dec. 18 reveals an anomalous ridge forming over the Barents-Kara Sea, which leads to the cold air accumulation over western Siberia. The pressure anomaly subsequently shifted westward to mature into a blocking high which created a wave-train pattern downstream, advecting the cold air eastward towards East Asia and Japan. The sequence of events was also apparent in multiple cases throughout the season. This study suggests that there is a strong and systematic linkage in the intraseasonal timescale between the atmospheric condition over the Barents-Kara Sea and the cold air accumulation over the Eurasian continent, leading to the anomalous cold air outbreak over East Asia and Japan. The mechanism may also provide explanation to extreme winter conditions such as those observed during the winter of 2010/2011.

著者

Kenji Kai Kei Kawai Kazuma Ohara Yuki Minamoto Yoshitaka Jin Teruya Maki Jun Noda Tatsuo Shiina Enkhbaatar Davaanyam

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19, pp.269-273, 2023 (Released:2023-11-03)

参考文献数

17

---

The mass concentration of Asian dust in the atmosphere is an essential parameter of the atmospheric environment in East Asia. In April 2016, we conducted simultaneous observations using an optical particle counter (OPC) installed on a tethered balloon and a ceilometer in the Gobi Desert. We estimated the mass-extinction conversion factor MECF (gm−2) from the relationship between the dust extinction coefficient and dust mass concentration obtained by simultaneous observations. The MECF at Dalanzadgad in the Gobi Desert is 2.16 gm−2 at 910 nm and 1.91 gm−2 at 532 nm. A previous study on Asian dust showed that the values of the MECF were 1.78 gm−2 in Beijing, 1.40 gm−2 in Seoul, 1.18 gm−2 in Tsukuba (Japan), and 1.04 gm−2 at averaged AD-Net lidar stations in Japan. The MECF values decreased from the Asian dust source to the lee-side areas. This result suggests that the MECF depends on the size distribution of the dust.

著者

Daisuke Sugiyama Ryo Onishi Hironori Fudeyasu

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19, pp.246-252, 2023 (Released:2023-10-21)

参考文献数

13

---

This study proposes a deep learning approach called SolaCam to accurately estimate solar radiation from the images captured by cameras. The proposed SolaCam performs deep learning by utilizing both image features and theoretical maximum solar radiation that vary with time and location. The trained model is capable of accurately estimating solar radiation on the ground surface from sky images captured by smartphones, fixed-point cameras, and other devices. The developed SolaCam can use a remote sensing function, which estimates solar radiation, on inexpensive camera-equipped devices.

著者

Kenji Suzuki Yurika Hara Takuji Sugidachi Kensaku Shimizu Masatomo Fujiwara

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19, pp.261-268, 2023 (Released:2023-10-31)

参考文献数

28

被引用文献数

1

---

A new particle imaging radiosonde “Rainscope” has been developed, and for the first time, particle fall velocity measurement functionality was added to a balloon-borne device. Rainscope can capture a clear still image of precipitation particles in a cloud when they interrupt an infrared beam, using a CMOS camera equipped with an electronic shutter. It can also record the time when a particle passes the upper and lower built-in infrared sensors, enabling measurement of the velocity of falling precipitation particles. For ground testing in rain and snow, a ground-based Rainscope showed raindrop/snowflake size-fall velocity distributions similar to those obtained in previous studies. In a comparison with a Parsivel2 disdrometer in rain, the Rainscope results were in good agreement with the distributions obtained by an adjacent Parsivel2. In a test flight of Rainscope into a stratiform cloud, raindrops, mostly melted particles, snowflakes in the process of melting, graupel, and snowflakes were observed. It was observed that the fall velocity varied depending on the type of solid precipitation particles.

著者

Sachie Kanada Akira Nishii

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19, pp.70-77, 2023 (Released:2023-04-19)

参考文献数

18

被引用文献数

2

---

Ground-based radar observations of the concentric eyewalls (CEs) of supertyphoon Hinnamnor (2022) showed that CEs evolved as follows: (Stage 0) development of a distinct stationary band complex (SBC) downshear in moderate south-southeastward vertical wind shear (VWS), (Stage 1) maturity of the secondary eyewall (SE), (Stage 2) contraction of the SE, and (Stage 3) decay of the CE structures. From Stage 0 to Stage 1, the SBCs transitioned into an axisymmetric SE, and moats appeared a few hours after SE formation. Outer rainbands formed successively in the down-to-left shear quadrants and developed wide stratiform regions with a vast anvil cloud extending outward as they moved upshear. When the anvil cloud covered the right-shear quadrants, the stratiform regions started contracting. Evolutions of the doppler velocity fields were detected under the anvil and stratiform regions of each rainband. An intense convection developed at the inner edge of the contracting SE as regions with relatively high doppler-velocity merged. When the core region was surrounded by multiple well-developed rainbands, the inner eyewall weakened rapidly. The radar observations revealed the importance of moderate-to-weak VWS and development of a SE as a rainband complex during evolution of CEs.

著者

Takeshi Horinouchi Taiga Mitsuyuki

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2023-008, (Released:2023-03-10)

被引用文献数

1

---

The use of massive sailing ships has been proposed as a means of acquiring renewable energy. It has also been proposed that such ships can be used to reduce the intensity of tropical cyclones (TCs). Here we propose a basis for evaluating the dynamical impacts of numerous sailing ships on the atmosphere. The key parameter is the total sail area per unit horizontal area (referred to as β), which is proportional to the number of ships in the region of interest. From β, the enhancement in the effective surface drag can be evaluated. The maximum potential intensity theory for TCs predicts that, under ideal environmental conditions, the steady-state TC intensity decreases inversely to the drag enhancement if the ship-induced change in the effective enthalpy transfer is much weaker. For example, if β is 0.04%, the potential intensity in terms of squared maximum wind can be decreased by around 10%. The effect of the directional drag from the use of aerodynamic lift in sail operations is also formulated, and its impact on TCs is evaluated by using a slab boundary-layer approximation. Sails' effects on air-sea interaction are briefly discussed, and further studies needed are envisioned.