Masumi Zaiki

<title>Abstract</title>Tropical cyclone (TC) activities over the western North Pacific (WNP) and TC landfall in Japan are investigated by collecting historical TC track data and meteorological observation data starting from the mid-nineteenth century. Historical TC track data and TC best track data are merged over the WNP from 1884 to 2018. The quality of historical TC data is not sufficient to count the TC numbers over the WNP due to the lack of spatial coverage and different TC criteria before the 1950s. We focus on TC landfall in Japan using a combination of TC track data and meteorological data observed at weather stations and lighthouses from 1877 to 2019. A unified TC definition is applied to obtain equivalent quality during the whole analysis period. We identify lower annual TC landfall numbers during the 1970s to the 2000s and find other periods have more TC landfall numbers including the nineteenth century. No trend in TC landfall number is detected. TC intensity is estimated by an annual power dissipation index (APDI). High APDI periods are found to be around 1900, in the 1910s, from the 1930s to 1960s, and after the 1990s. When we focus on the period from 1977 to 2019, a significant increasing trend of ADPI is seen, and significant northeastward shift of TC landfall location is detected. On the other hand, TC landfall location shifts northeastward and then southwestward in about 100-year interval. European and US ships sailed through East and Southeast Asian waters before the weather station network was established in the late nineteenth century. Then, we focus on TC events in July 1853 observed by the US Naval Japan Expedition of Perry’s fleet and August 1863 by a UK Navy ship that participated in two wars in Japan. A TC moved slowly westward over the East China Sea south of the Okinawa Islands from 21 to 25 July 1853. Another TC was detected in the East China Sea on 15–16 August 1863 during the bombardment of Kagoshima in southern Japan. Pressure data are evaluated by comparing the observations made by 10 naval ships in Yokohama, central Japan during 1863–1864. The deviation of each ship pressure data from the 10 ships mean is about 2.7–2.8 hPa.

Thunderstorm and cloud activities sometimes show a 27-day period, and this has long been studied to uncover a possible important link to solar rotation. Because the 27-day variations in the solar forcing parameters such as solar ultraviolet and galactic cosmic rays become more prominent when the solar activity is high, it is expected that the signal of the 27-day period in meteorological phenomena may wax and wane according to the changes in the solar activity level. In this study, we examine in detail the intensity variations in the signal of the 27-day solar rotational period in thunder and lightning activity from the 18th to the 19th centuries based on 150-year-long records found in old diaries kept in Japan and discuss their relation with the solar activity levels. Such long records enable us to examine the signals of solar rotation at both high and low solar activity levels. We found that the signal of the solar rotational period in the thunder and lightning activity increases as the solar activity increases. In this study, we also discuss the possibility of the impact of the long-term climatological conditions on the signals of the 27-day period in thunder/lightning activities.

Debris avalanches caused by volcano sector collapse often form characteristic depositional landforms such as hummocks. Sedimentological and geomorphological analyses of debris avalanche deposits (DADs) are crucial to clarify the size, mechanisms, and emplacement of debris avalanches. We describe the morphology of hummocks on the northeastern flank of Mt. Erciyes in Kayseri, central Turkey, likely formed in the late Pleistocene. Using a remotely piloted aircraft system (RPAS) and the structure-from-motion and multi-view stereo (SfM-MVS) photogrammetry, we obtained high-definition digital elevation model (DEM) and orthorectified images of the hummocks to investigate their geometric features. We estimated the source volume of the DAD by reconstructing the topography of the volcano edifice using a satellite-based DEM. We examined the topographic cross sections based on the slopes around the scar regarded as remnant topography. Spatial distribution of hummocks is anomalously concentrated at a certain distance from the source, unlike those that follow the distance-size relationship. The high-definition land surface data by RPAS and SfM revealed that many of the hummocks are aligned toward the flow direction of the debris avalanche, suggesting that the extensional regime of the debris avalanche was dominant. However, some displaced hummocks were also found, indicating that the compressional regime of the flow contributed to the formation of hummocks. These indicate that the flow and emplacement of the avalanche were constrained by the topography. The existing caldera wall forced the initial eastward flow to move northward, and the north-side caldera wall forced the flow into the narrow and steepened outlet valley where the sliding debris underwent a compressional regime, and out into the unconfined terrain where the debris was most likely emplaced on an extensional regime. Also, the estimated volume of 12-15 × 108 m3 gives a mean thickness of 60-75 m, which is much deeper than the reported cases of other DADs. This suggests that the debris avalanche must have flowed further downstream and beyond the current DAD extent. Assessments of the DAD incorporating the topographic constraints can provide further insights into the risk and mitigation of potential disasters in the study area.

<p> Past meteorological records are important for improving our understanding of past, present, and future climates. Imaging and digitization of historical paper-based instrumental meteorological records must be carried out before these records are lost to decay. This kind of activity called "data rescue" is now taking place at many institutions around the world. A data rescue project is underway to preserve Japanese instrumental meteorological records from the 19th century. These data were collected by foreign residents and visitors, Japanese scientists influenced by Dutch science, and by Japanese merchants. Recently, meteorological measurements taken at Mito from 1852 to 1868, and at Yokohama in 1872 and 1873 have been found. Based on instrumental records collected through this data rescue project, a warmer climate in the 1840s and 1850s around the South-eastern Kanto Region has been identified. Large year-to-year variations of winter temperatures have also been detected. </p>

<p> Climate variations in East Asia during the Little Ice Age are reconstructed using wind records together with chronicles of weather disasters in Japan and China, as well as weather observations from Okinawa in the 1850s. The results of analyses are as follows: (1) On the basis of numerous records that remain for the southern coast of Japan and the south-eastern coast of China, it appears that many rainstorm disasters occurred during the summer period in both Japan and China. They usually took place one or two months later in Japan than in China; (2) Observations in Naha show that, when air pressure drops considerably, wind speed is very high and its direction rotates. Following unusual air pressure falls in Naha, strong winds caused disasters in China or in Japan. It is thought that these events are linked to movements of typhoons; (3) Increases in windstorm damage occurred during different periods in Japan and China. This may be related to changes in atmospheric circulation. Cool summer periods are observed around 1705, 1740, 1765, 1785, 1830, and 1845. The year 1855 marks a turning point between periods with prevailing cool states and periods with prevailing warm states.</p>

<p> Father Louis Théodore Furet (1816-1900) was a missionary of the Société des Missions étrangères de Paris (Paris Foreign Missions Society) who was posted in the Far East from 1853 to 1869. The discovery of his manuscript of meteorological observations undertaken at Naha, Okinawa, Ryukyu Islands, Japan, opens up new perspectives on the historical climatology of 19^th century Japan. Furet arrived at Naha (spelled Nafa in the 19^th century literature), the main port of Okinawa, on 26 February 1855. From December 1856 to September 1858, he carried out meteorological observations five times a day: at 6 and 10 am, 1, 4 and 10 pm. The hydrological engineer Alexandre Delamarche (1815-1884) calibrated the meteorological instruments entrusted to Father Furet by the French Dépôt de la Marine. The observations were carried out following the meteorological procedures in use in France in the 1850s. The atmospheric pressure data are given by the barometer readings, the barometer-temperature readings and the computed temperature-corrected atmospheric pressure. The pressure data are controlled and corrected, where necessary, using the Delcros and Haeghens formula which was in use in the 1850s. The historical atmospheric pressure observations are compared to the present-day long-term averages at Naha. During his observation period a typhoon was witnessed by Father Louis Furet on 18 May 1857. Other low atmospheric pressure observations probably correspond to extra-tropical storms. In such an event, the Dutch ship van Bosse was wrecked near the island Tarama but the captain, his wife and the whole crew survived. They were helped by the inhabitants of the island and were later transferred to Naha, Okinawa, where they met the three French missionaries and finally got a passage from the Dutch trading post at Decima to Batavia (present-day Jakarta).</p>

This study employs Geographical Information Systems software to develop a classification system for typhoons (TYs) affecting Japan (1951-2011) and uses that system to investigate the spatial and temporal variations of storm tracks and their connection to the location and strength of the North Pacific subtropical high (NPSH). TYs coming within a 300-km buffer zone around the four main islands of Japan (JZOI) are grouped into two main types: those that remain on the Pacific Coast (PC) and those that enter the Japan Sea (JS). Results indicate that fewer TYs enter the JZOI when the NPSH extends strongly to the west and more reach Japan when it extends to the northwest. The winds around the periphery of the NPSH affect the recurvature of TYs directing them either west towards the China Mainland or around the western edge of the high towards Japan. More importantly, during periods when greater numbers of TYs affect the PC side of Japan (PC+), the NPSH extends to the southwest. However, during periods when greater numbers of TYs affect JS side of Japan (JS+), the NPSH extends to the northwest closer to Japan. The southwest extension of the NPSH enables TYs to recurve and pass to the eastern side (PC) of Japan while the northwest extension forces TYs around or across Japan into the JS. An important finding is that the moderately different positions of the NPSH change the atmospheric circulation around Japan dramatically and affect whether TYs pass over the PC side or the JS coast side of Japan. At the interannual time scale, increased JS+ years were observed since 1980 because of the frequent occurrence of the Pacific-Japan pattern. We also found that at the interdecadal time scale, PC+ years have increased due to the southwestward extension of the NPSH since 1980.

In the present study, we estimated the July maximum temperature variations from 1830 to 2011 in the town of Kawanishi in the southern part of Yamagata prefecture using daily weather reports and observations documented in an old personal diary. Using historical weather reports, we computed the number of “fine-weather” days for each July during the study period. Then, July maximum temperatures in Kawanishi were estimated using a simple linear regression analysis based on the relationship between the July maximum temperature and number of “fine-weather” days, computed from historical weather reports. By comparing the time series of estimated temperatures with those of historical instrumental temperature data in the late 19th century, we found that the variation in the estimated temperature correlated well with that of the instrumental temperature data. This indicates that the estimated results in the present study are highly reliable. The results of this analysis showed that there were cool periods in the 1830s, 1860s, 1900s, and a period extending from the 1980s to the early 1990s. Those cool periods in the 1830s, 1860s, and 1900s coincided with poor rice harvests and severe famines in northern Japan. Warm summers were observed in the 1850s, a period extending from the 1870s to 1880s, and 1920s. We found that temperatures in the early 1850s were similar to those of warm summers in the late 20th century.

The temperature and pressure differences between Tokyo and Nagasaki were used to reconstruct past climate conditions. January and July in each available year since the 1820s were classified into several types with characteristic sea level atmospheric pressure patterns. This results in 18 years of pre-1881 data and a continuous series thereafter. The series indicate that the warming after 1900 (after the end of the so-called Little Ice Age) and again after 1960 can at least partly be attributed to an increase in the frequency of warm circulation pattern types at the expense of cold types. The difference in nature of the shifts in circulation types that occurred in the late nineteenth century compared with that in the late twentieth centuries suggests that the mechanism behind the warming in the late nineteenth century differs from that in the late twentieth century.

This paper outlines some characteristics of the academic activity in the Japanese colonial setting, with special reference to meteorology on the southern colonial frontier of Japan's Empire, through the works of Ogasawara Kazuo at Taihoku Imperial University. We first review the establishment of Japan's overseas meteorological network and the corresponding institutionalization of meteorology in that period. We will then consider Ogasawara's academic works at Taihoku Imperial University, and analyse how a pure scientist shifted to colonial management and justified Japan's expansion as far as Australia and New Zealand. We will examine his moral dilemma, how he wrote his work on tropical climate, and his interpretation of Huntingtonian environmental determinism. Through the analysis of Ogasawara's works, we are able to see at least one aspect of Japan's colonial science, its syncretic nature and pragmatism.

We have recovered instrumental temperature and pressure observations from Tokyo covering the periods 1825-1828. 1839-1855, and 1872-1875; from Yokohama covering the periods 1860-1871 and 1874; from Osaka covering the periods 1828-1833 and 1869-1871; and front Kobe covering the periods 1869-1871 and 1875-1888. The newly recovered records contain data before the 1870s, which is a period where, until recently, no instrumental data in Japan were believed to exist. Their addition to the previous backward extension of Japanese series, as based on the recently recovered intermittent Dejima/Nagasaki series 1819-1878, implies that the nineteenth-century extension of the Japanese instrumental record no longer contains major temporal gaps. The recovered data were used for a preliminary calculation of the west-Japan temperature (WJT) series, which is a representative temperature series for the area. The existence of a warm epoch in the 1850s over W-Japan and a downward temperature trend till the early twentieth century, as previously inferred from documentary data, is confirmed from the WJT data. The pressure data implies that the temperature differences between the nineteenth and twentieth Centuries are at least partly caused by a change in atmospheric circulation. Copyright (c) 2006 Royal Meteorological Society.

Instrumental observations from Dejima (Nagasaki), Japan, taken under the responsibility of the Dutch, covering the periods 1819-28, 1845-58, and 1871-78, have been recovered. The Dejima series overlaps by six months the modern Nagasaki Observatory series, which covers 1878-present. The recovered data extend the start of the instrumental Japanese series back from 1872 to 1819, leaving major gaps during 1829-44 and 1859-71.

[1] When a study is made of past climatic variations, it is preferable to obtain as long an instrumental record as possible. In Japan, the earliest official meteorological observations by JMA (Japan Meteorological Agency) date back to Hakodate in 1872. For about 130 years, the frequency and time of daily observation has varied. This is one of the major factors in creating data inhomogeneity. Accordingly, statistical estimation has been attempted to bridge the gap in daily mean temperatures caused by the limited number of daily observations. A Multiple Linear Regression Analysis was practically applied in the estimation of the daily mean temperature. The true value obtained from 24 hourly observational values (real daily mean temperature) was compared to a derived result using only three to four plus maximum and minimum daily observed temperatures. A high correlation between real values and estimated values was proven to exist.