著者

Anu Gupta Jun Matsumoto

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.18, pp.211-217, 2022 (Released:2022-09-28)

参考文献数

19

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This study investigated the spatial and temporal modulation of aerosol species by monsoon intraseasonal oscillation (MISO) using the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations from 2003 to 2019. The climatological spatial distribution of aerosol species showed long-range transport of sea-salt and dust to Indian landmass from the Arabian Sea and desert regions of the Arabian Peninsula, respectively. While organic matter, black carbon, and sulfate originated mainly in India. In the eight MISO phases, southwesterly/westerly strengthening/weakening was responsible for aerosol species transport and spatial distribution. During MISO break to active transition phases 2-5, strong southwest monsoon winds transported sea-salt aerosols from the Arabian Sea to the Indian region. In the active-to-break transition phases 5-7, dust transport strengthened from the Arabian Peninsula. The dust aerosols over the Indian subcontinent peaked in phases 6 and 7. In phases 2-5 (6-8, 1), direction of strong winds along the Indo-Gangetic Plain influenced increased levels of organic matter, sulfate, and black carbon aerosols in the western/northwestern (eastern/northeastern) regions of India. These dynamic spatial changes in aerosols caused by MISO over the Indian region influence the shortwave and longwave radiation balances that can influence monsoon circulation.

著者

Amane Nakamura Tsubasa Kohyama

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.18, pp.236-242, 2022 (Released:2022-10-31)

参考文献数

18

---

Analysis of the El Niño-Southern Oscillation (ENSO) phenomena has conventionally been performed using deviations from the mean. However, the question remains as to whether the mean is appropriate as the reference state, since it is sensitive to the existence of a few extreme events. In this study, the validity of the mean and mode as a reference is compared using an idealized simulation model. We show that the mode is not affected by the asymmetry of El Niño and La Niña and is more stable as a reference than the mean. Then, this result is also demonstrated using observed data. Observations also show that the relationship between the ENSO amplitude and the zonal shifts of the ENSO anomalies is more emphasized if the mode is employed. For the variables in the ocean interior, differences between the mode-based and mean-based methods appear throughout all seasons.

著者

Takashi Maki Taichu Y. Tanaka Tsuyoshi Koshiro Atsushi Shimizu Tsuyoshi T. Sekiyama Mizuo Kajino Yasunori Kurosaki Toshiya Okuro Naga Oshima

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.2022-035, (Released:2022-09-06)

被引用文献数

1

---

Ensemble future climate projections were performed using the Meteorological Research Institute Earth System Model version 2.0 (MRI-ESM2.0) for sand and dust storms (SDS), which have a significant social, economic, and climatic impact on East Asia. A past replication experiment using MRI-ESM2.0 reproduced the decreasing trend of SDS in the Gobi Desert in the early 21st century. Prediction experiments by MRI_ESM2.0 in CMIP6 future scenarios indicated no significant differences in the total amount of SDS emissions in the Gobi Desert for 2015-2100; however, SDS emissions increased with warmer scenarios in spring and autumn. In particular, March in the highest warming scenario (SSP5-8.5) exhibited an annual increase rate in SDS emissions of 3.0% for 2015-2100. Friction velocity was the factor most highly correlated with SDS emissions, with a correlation generally higher than 0.6 for all climate scenarios throughout the year. In spring and autumn, snow cover exhibited a low negative correlation with SDS emissions, while ground temperature exhibited a positive correlation. The increase in SDS emissions and subsequent dust transport by midlatitude westerlies in spring and autumn in the accelerated warming scenarios is likely due to the changes in friction velocity and erodibility due to the decrease in snow accumulation.

著者

Masashi Niwano Masami Suya Koichi Nagaya Satoru Yamaguchi Sumito Matoba Ikuo Harada Nozomu Ohkawara

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.18, pp.193-198, 2022 (Released:2022-09-07)

参考文献数

34

被引用文献数

3

---

Despite the importance of seasonal snow in Japan, quantitative information on seasonal snow mass in the whole area is lacking. To understand the current mass balance of seasonal snow cover, we develop a method to quantify the mass balance of seasonal snow all over Japan using the Japan Meteorological Agency's operational regional atmospheric model, Local Forecast Model (LFM), as well as the snow physics model, Snow Metamorphism and Albedo Process (SMAP). Our model simulations using the LFM-SMAP model chain show that the seasonal snow water equivalent (SWE) evolution is mostly controlled by snowfall and runoff. It is estimated that the seasonal peak area-integrated SWE in Japan reaches 42.2 Gt on average during the 2017-2022 winters, and 60.1 Gt (+43% with respect to the average) and 22.0 Gt (−48%) during relatively heavy (2017-2018) and relatively light (2019-2020) snow years, respectively. The ratios between seasonal peak area-integrated SWE and winter-accumulated (November to February) snowfall amounts for the heavy, average, and light snow years are 83%, 74%, and 59%, respectively.

著者

Takehiko Kobori Masayuki Maki Yasushi Fujiyoshi Masato Iguchi Seiji Fukushima

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.2022-037, (Released:2022-09-09)

被引用文献数

1

---

We developed a method for estimating the height and growth rate of volcanic eruption columns, at high-temporal resolution, by processing vertical cross-sectional images of areas around the crater obtained with a marine radar tilted on its side. We applied our method to 127 eruptions occurring at Sakurajima (Kagoshima, Japan) from June to December 2019 and successfully estimated the time-series height of the eruption column and its growth rate every 2.5 seconds. In 48 cases, we obtained the maximum height of the eruption column and confirmed that these results were consistent with those estimated using meteorological radar. Although the maximum height estimated with our method tended to be lower than that observed by monitoring cameras, results could be obtained even when observations were difficult due to cloud effects, etc.

著者

Keita Fujiwara Ryuichi Kawamura

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.18, pp.181-186, 2022 (Released:2022-08-31)

参考文献数

32

被引用文献数

2

---

This study investigated a recent tendency of interannual precipitation variations during the Baiu season (June–July) in southern Kyushu, Japan. Long-term satellite precipitation observations revealed a significant amplification of the interannual variability of Baiu precipitation after the beginning of this century and the appearance of a quasi-quadrennial variation (QQV). Composite analyses with respect to the unstable regime of Baiu activity when the QQV prevailed suggested a possible link between the Indo-western Pacific Ocean Capacitor (IPOC) mode and the QQV. Regression analyses with an IPOC index showed the dominance of an anomalous anticyclone in the lower troposphere centered over the South China Sea and the Philippine Sea and enhanced poleward moisture transport along its western periphery. The interdecadal shift in remote IPOC influence seen around the year 2000 featured the westward (northward) extension of the low-level anomalous anticyclone toward the Bay of Bengal (southern Japan); consequently, the significant moisture flux convergence area covered southern Kyushu during the unstable Baiu regime, consistent with the QQV appearance during the same period. It is also inferred that the IPOC mode modulation may come from the increased impact of central Pacific El Niño/Southern Oscillation on the IPOC in recent decades.

著者

Masashi Niwano Masami Suya Koichi Nagaya Satoru Yamaguchi Sumito Matoba Ikuo Harada Nozomu Ohkawara

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.2022-031, (Released:2022-08-11)

被引用文献数

3

---

Despite the importance of seasonal snow in Japan, quantitative information on seasonal snow mass in the whole area is lacking. To understand the current mass balance of seasonal snow cover, we develop a method to quantify the mass balance of seasonal snow all over Japan using the Japan Meteorological Agency's operational regional atmospheric model, Local Forecast Model (LFM), as well as the snow physics model, Snow Metamorphism and Albedo Process (SMAP). Our model simulations using the LFM-SMAP model chain show that the seasonal snow water equivalent (SWE) evolution is mostly controlled by snowfall and runoff. It is estimated that the seasonal peak area-integrated SWE in Japan reaches 42.2 Gt on average during the 2017-2022 winters, and 60.1 Gt (+43% with respect to the average) and 22.0 Gt (−48%) during relatively heavy (2017-2018) and relatively light (2019-2020) snow years, respectively. The ratios between seasonal peak area-integrated SWE and winter-accumulated (November to February) snowfall amounts for the heavy, average, and light snow years are 83%, 74%, and 59%, respectively.

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

Yasutaka Hirockawa Teruyuki Kato

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.2022-027, (Released:2022-06-23)

---

The procedures for identifying and classifying heavy rainfall areas of linear-stationary type (LS-HRAs) from the distributions of radar/raingauge-analyzed precipitation amounts (RAP) were improved to extract “senjo-kousuitai” with elongated and stagnant characteristics that causes localized heavy rainfall in Japan. The improved procedures were verified based on subjective judgments (‘certainty’, ‘doubtful’, and “suspect’) whether LS-HRAs possess the characteristics of typical senjo-kousuitai. Criteria for excluding LS-HRAs judged to be ‘suspect’, mainly associated with tropical cyclones (TCs) and non-stationary mesoscale convective systems, were introduced to optimally extract senjo-kousuitai events. The criteria were determined by the distance between LS-HRAs and TC centers (DLT), the maximum total RAP of LS-HRA (total RAP), and the properties of each RAP distribution at every hour during the LS-HRA extraction period, e.g., DLT ≤ 500 km and total RAP < 200 mm. By applying these criteria, 372 senjo-kousuitai events were extracted from 452 LS-HRAs during the warm seasons (April–November) in 2009-2020, although approximately 35% of the LS-HRAs judged to be ‘suspect’ were not excluded. The criteria associated with TCs excluded them more effectively than the other factors. The improved procedures for extracting senjo-kousuitai events are expected to be used effectively for their statistical analyses.

著者

Michiya Hayashi Hideo Shiogama

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.18, pp.96-103, 2022 (Released:2022-05-17)

参考文献数

47

被引用文献数

4

---

The technique for composing a small subset of global climate models is critical to provide climate scenarios for impact and adaptation studies of regional climate changes. A recent study developed a novel statistical method for selecting a mini-ensemble of five climate models from the Coupled Model Intercomparison Project Phase 6 for widely capturing different future projections of Japanese climate across eight atmospheric variables at the surface. However, it remains unclear which mini-ensemble model contributes to efficiently covering the full projection ranges. Here, we rank each mini-ensemble projection around Japan among a full ensemble, showing that the selected five models capture the full ranges without systematic biases, except for relative humidity. Furthermore, we find that the widespread global warming level contributes to covering well the projection uncertainties in the daily-mean, maximum and minimum air temperatures and downward longwave radiation but not in precipitation, solar radiation, relative humidity, or wind speed. As the last four variables are sensitive to various factors, such as large-scale circulation and aerosol-forcing changes, rather than global-mean temperature changes, the model selection method featured here is preferable for capturing the wide future projection ranges in Japan.

著者

Yukie Moroda Kazuhisa Tsuboki Shinsuke Satoh Katsuhiro Nakagawa Tomoo Ushio Hiroshi Kikuchi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2022-018, (Released:2022-04-15)

被引用文献数

1

---

A rapid rise of the lightning activity center in the upper part of a cloud is called a lightning bubble (LB). It remains unclear how LBs occur in thunderstorm clouds. Recently, high-spatiotemporal resolution data obtained by a phased array weather radar enabled observation of temporal changes in the three-dimensional structure of precipitation cores in a precipitation cell. To understand the mechanism by which LBs occur, we examined the relationship between the time-evolution of precipitation cores and the flash initiation points.After a precipitation core developed in an isolated thundercloud, the top height of the core reached its highest altitude and then started to descend. Meanwhile, the echo tops above the core continued to rise, which is termed an upward reflectivity pulse (URP). Over an hour, nine URPs were successively observed in the thundercloud. The average tracking period of the URPs was 3.9 minutes. Flash initiation points appeared near the highest points of the URPs and continued to rise with time. These observational results suggest that URPs cause LBs by enhancing the electric field, via the separation of graupel and ice crystals near the highest points of ascending URPs.

著者

Kei Kawai Hitoshi Matsui Reiji Kimura Masato Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.239-245, 2021 (Released:2021-12-18)

参考文献数

41

被引用文献数

4

---

The emission of Asian dust in arid regions of East Asia is controlled by many land surface parameters such as snow cover, soil moisture, and vegetation. In climate models, these factors are represented by the threshold friction velocity u*t, but its treatment has large uncertainties. Here we show that the treatment of u*t is important for estimating the emissions, transport, and climate impacts of Asian dust. Our global aerosol model simulates dust event frequencies that better agree with observations in East Asia when u*t over a smooth surface is changed from the default value of 0.23 m s−1 to an observation-based value of 0.40 m s−1. Also, seasonal Asian dust emissions become more variable, increasing by 31% in spring and decreasing by 46% in summer and fall, and the annual amounts of Asian dust transported and deposited over the North Pacific (Arctic) increase by 43% and 49% (130% and 73%), respectively. Our results demonstrate that better representation of u*t in climate models is necessary to improve estimates of the emissions and transport of Asian dust and better understand its roles in the Earth system, such as its interactions with radiation, clouds, snow/ice albedo, and land and ocean biogeochemistry.

著者

Yasutaka Hirockawa Teruyuki Kato

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2022-003, (Released:2021-12-28)

被引用文献数

4

---

We propose a new application method in which radar/raingauge-analyzed precipitation amounts (RAP) produced by the Japan Meteorological Agency are spatially converted into 5km-resolution data, in addition to a three-hourly accumulation procedure, in order to statistically analyze localized heavy rainfall areas (HRAs) for a long period. A long-term trend and homogeneity in the appearance frequency of RAP with 5km-resolution converted by several methods, including the conventional method, are statistically evaluated in comparison with rain-gauge observations. The results indicate that the following application method is the most suitable to represent long-term variations in the appearance frequency of HRAs; (1) the converted value of RAP from 1 km to 5 km resolution is set to the 90th percentile value in 30 segments with 1km-resolution included in a grid with 5km-resolution, and (2) this spatial conversion is conducted after accumulating original RAP with 1km-resolution for three hours. Statistical analyses were performed for the appearance frequency of HRAs extracted from 5km-resolution RAP that were produced by the new application method, which indicates that the number of HRAs of the linear-stationary type could be increased without compromising the characteristics of HRAs extracted by the conventional method.

著者

Kazuya Yamazaki

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.224-227, 2021 (Released:2021-12-16)

参考文献数

11

---

A novel lightweight and high-accuracy variant of the image pan-sharpening technique is designed for Himawari-8 multispectral images. This method, named Additive Template Sharpening, injects higher-wavenumber components of the highest-resolution Band 3 images into lower-resolution visible or shortwave infrared images, thereby providing multispectral high-resolution images. This injection is realized by adding inter-band differential field to the high-resolution band, making use of the specific pixel arrangement of the Himawari-8 imager for simple and accurate coordinate transformations. Both subjective inspection of RGB composite images and objective evaluation of the upsampling indicate that Additive Template Sharpening exhibits higher accuracy than existing methods for Bands 1-6 of Himawari-8. This technique not only enables operational forecasters to diagnose atmospheric conditions in more details using higher-resolution RGB composites, but also provides higher-quality true-color imagery for the public.

著者

Kei Kawai Hitoshi Matsui Reiji Kimura Masato Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-042, (Released:2021-11-02)

被引用文献数

4

---

The emission of Asian dust in arid regions of East Asia is controlled by many land surface parameters such as snow cover, soil moisture, and vegetation. In climate models, these factors are represented by the threshold friction velocity u*t, but its treatment has large uncertainties. Here we show that the treatment of u*t is important for estimating the emissions, transport, and climate impacts of Asian dust. Our global aerosol model simulates dust event frequencies that better agree with observations in East Asia when u*t over a smooth surface is changed from the default value of 0.23 m s−1 to an observation-based value of 0.40 m s−1. Also, seasonal Asian dust emissions become more variable, increasing by 31% in spring and decreasing by 46% in summer and fall, and the annual amounts of Asian dust transported and deposited over the North Pacific (Arctic) increase by 43% and 49% (130% and 73%), respectively. Our results demonstrate that better representation of u*t in climate models is necessary to improve estimates of the emissions and transport of Asian dust and better understand its roles in the Earth system, such as its interactions with radiation, clouds, snow/ice albedo, and land and ocean biogeochemistry.

著者

Kazuto Takemura Hitoshi Mukougawa

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-029, (Released:2021-08-20)

被引用文献数

4

---

This study presents a possible large-scale factor of tropical cyclogenesis over the western North Pacific, which is triggered by Rossby wave breaking to the east of Japan. More than half of the wave breaking cases is accompanied by the tropical cyclogenesis. Results from a composite analysis for the wave breaking cases indicate that the genesis and development of tropical cyclones are dominant over the southwest quadrant of the wave breaking center, where an intrusion of the upper-level potential vorticity caused by the wave breaking and the consequent enhanced convection are seen. The number of tropical cyclones in the wave breaking cases exponentially increases in time during the developing stage of the wave breaking. The results of composite analysis further indicate that lower-level strong wind convergence and the associated enhanced convection, which are resulting from the wave breaking, is favorable conditions for the tropical cyclogenesis. An enhanced monsoon trough accompanied by the Pacific–Japan pattern resulting from the enhanced convection can regulate tracks of the tropical cyclones. These results show that the Rossby wave breaking can trigger the tropical cyclogenesis over the western North Pacific, through the southwestward intrusion of the upper-level potential vorticity and the consequent enhanced convection.

著者

Masaya Kuramochi Hiroaki Ueda Chiaki Kobayashi Youichi Kamae Koutarou Takaya

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.17B-001, (Released:2021-08-05)

被引用文献数

7

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The anomalous warm winter from December 2019 to February 2020 over East Asia, particularly the anticyclonic anomaly around Japan, was examined from the teleconnection perspective anchored by a warmed Indian Ocean and the El Niño Modoki. In the upper troposphere, high–low–high wave patterns progressing from the Arabian Sea toward Japan via the southern region of China, coupled with the wave-activity flux diagnosis, implicate the propagation of stationary Rossby waves caused by enhanced convection in the western Indian Ocean and suppressed convection around the Maritime Continent. These anomalous convective activities could be responsible for the northward displacement of the subtropical jet and the ensuing warm conditions over East Asia. The atmospheric response to the observed diabatic heating by means of the linear baroclinic model well reproduced the observations. Moreover, sensitivity experiments of the atmospheric general circulation model to sea surface temperature (SST) anomalies, especially in the warmed western Indian and central Pacific oceans, can help understand the anomalous subsidence over the Maritime Continent sector and subsequently weakened convection. The warmer SST observed around the Maritime Continent alone reproduces the enhancement of rainfall and subsequent cold anomalies around Japan, suggesting the importance of trans-basin interaction for teleconnection towards East Asia.

著者

Pin-Ying Wu Tetsuya Takemi

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-024, (Released:2021-06-23)

被引用文献数

1

---

Identical twin experiments with and without topography are conducted with the Weather Research and Forecasting (WRF) model in an idealized framework to investigate the impact of topography on the initial error growth associated with moist convection. A topography is set as a single Gaussian shape mountain with a peak height of about 1000 m. Both experiments show clear diurnal cycles, while moist convection develops earlier and organizes to a larger size in the experiment with topography. To evaluate the initial error growth, a metric referred to as moist difference total energy (MDTE) is proposed to represent the differences between the two simulations in twin experiments. The horizontal spatial distribution, temporal evolution, and horizontal wavenumber space of the MDTE suggest that the error growth is greatly dominated by the different features of convection development between the two experiments. The analysis based on individual cloud areas shows that the convective clouds developing over the mountain have smaller MDTE at the early stage of development.

著者

Long Trinh-Tuan Jun Matsumoto Fredolin T. Tangang Liew Juneng Faye Cruz Gemma Narisma Jerasorn Santisirisomboon Tan Phan-Van Dodo Gunawan Edvin Aldrian Thanh Ngo-Duc

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.1-6, 2019 (Released:2019-01-19)

参考文献数

38

被引用文献数

7 27

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The Quantile Mapping (QM) bias correction (BC) technique was applied for the first time to address biases in the simulated precipitation over Vietnam from the Regional Climate Model (RegCM) driven by five Coupled Model Intercomparison Project Phase 5 (CMIP5) Global Climate Model (GCM) products. The QM process was implemented for the period 1986-2005, and subsequently applied to the mid-future period 2046-2065 under both Representative Concentration Pathway (RCP) 4.5 and RCP 8.5. Comparison with the original model outputs during the independent validation period shows a large bias reduction from 45% to 3% over Vietnam and significant improvements in representing precipitation indices (PI) after applying the QM technique. Moreover, the ensemble average of the BC products generally performed better than an individual BC member in capturing the spatial distribution of the PIs. A drier condition with a longer rainfall break, and shorter consecutive rainfall events are anticipated over Northern and Central Vietnam during their respective wet seasons in the mid-future. Furthermore, this study showed that the QM method minimally modified the future changes in PIs over most of Vietnam; thus, these corrected projections could be used in climate impacts and adaptation studies.

著者

Yuta Katsuyama Masaru Inatsu

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-006, (Released:2021-01-27)

被引用文献数

2

---

This study developed a volume scan-type disdrometer and investigated the size distribution of solid-precipitation particles observed by flux- and volume-scan type disdrometers, installed in 2016-2017 winter in Sapporo, Japan. The former disdrometer detected particles, by line sensors, of which frequency is proportional to the particle number per area. On the other hand, the latter directly observed the particle number per volume using an image sensor. The flux-scan data are known to have the bias of more frequency in higher-speed (or larger-size) particles, but this bias was hardly corrected due to the error of estimated particles' velocity. It was first validated that the volume scan-type disdrometer could observe particle size between 0.5 mm and 13 mm, consistently with the flux scan-type one. Then, we examined how many events showed the difference of the size distribution between the two disdrometers with the Kolmogorov-Smirnov test. The result showed that 84% of the total events examined fell into the class where they were significantly different, partially due to fast-falling graupels.