Takehiko Mikami

• Tokyo Metropolitan University

European and US ships sailed in the vicinity of Japanese waters before the weather station network was established in Japan during the late Edo period in the 18th and 19th centuries. We focused on the ship log weather records on vessels sailing through Japanese waters during this period. The 18th-century weather records came mostly from expedition...

The East Asian winter monsoon causes orographic snowfall over the windward side of the Japanese islands (facing the Sea of Japan and the northwesterly winter monsoon flow) and negative temperature anomalies around Japan. Daily weather information recorded in old Japanese diaries can provide useful information on the historical occurrences of snowfa...

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 d...

Greening of cities is one of the mitigation strategies for urban hot environments in summer, because green parks in cities have a lower temperature than the surrounding built environment in summer, called cool islands phenomena. This study took the micro-meteorological measurements in an urban park (Shinjyuku Gyoen, Tokyo Japan) and analyzes the ve...

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 s...

This study analyzed precipitation data during the 1860s in Yokohama, Japan, using observations made by an American Christian missionary, J.C. Hepburn. Hepburn's meteorological data included monthly maximum, mean, and minimum temperatures, monthly precipitation, and the number of rain days in each month. The climate during the late 1860s was charact...

Historical documentary sources provide important data for the reconstruction of typhoons before the collection of systematic instrumental records by official government meteorological agencies. In this paper, we describe five sources that we use to provide details about typhoons affecting the four main islands of Japan in 1877. The sources describe...

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 cli...

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...

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 signa...

The Olympic Games will be held in Tokyo in 2020 and the period will be the hottest period of the year in Japan. Marathon is a sport with a large heat load, and it is said that the risk of heat stroke rises more than other sports activities. The thermal environment of the 2020 Tokyo Olympic marathon course is analyzed by using wet-bulb globe tempera...

This chapter discusses climate variations in Tokyo, based on the reconstructed summer temperatures since the eighteenth century and instrumental meteorological data from the nineteenth century to the present. During the Little Ice Age, especially in the eighteenth century, remarkable cool episodes occurred in the 1730s, the 1780s, and the 1830s. Th...

We reconstructed the monthly mean of daily maximum temperature variations for July and August since 1779 in Hiroshima, western Japan, based on the number of rainy days documented in historical records. We investigated the spatial distributions of the correlation coefficients between the number of rainy days and temperatures for June, July, and Augu...

Dominant components of spatio-temporal variations were derived from principal component analysis of spatially high-density data on air temperature and pressure over the Kanto region in summer, obtained from our own observation network. Their connectivity is discussed from the viewpoints of meteorological conditions and diurnal variations. The spati...

We investigate the relationship between sea breeze penetration and anomalously high summer daytime temperatures in the inland suburbs of Tokyo, with consideration of the relative position of sea breeze fronts. We use data from the high‐density temperature observation network (Extended‐ METROS ) established by our research group to clarify in detail...

Interdecadal changes in the relationship between summer rainfall over Japan and the western edge of the North Pacific subtropical high (NPSH) were investigated for the 1901–2000 period. In this study, indices describing the zonal and meridional displacement of the western edge of the NPSH (NPSHI-Z and NPSHI-M, respectively) were used for the analys...

The urban heat island is a well-known phenomenon that impacts a wide variety of city operations. With greater availability of cheap meteorological sensors, it is possible to measure spatial patterns of urban atmospheric characteristics with greater resolution. To develop robust and resilient networks, recognizing sensors may malfunction, it is impo...

The cooling phenomenon brought by a large urban green park in Tokyo to its surrounding town area was evaluated. Micrometeorological measurements conducted during summer nights revealed the heat balance for the park's forest canopy. Highly reliable measurement runs, in which independent evaluations agreed within 20%, showed that the cooling amount w...

City-scale warming is becoming a serious problem in terms of human health. Urban green spaces are expected to act as a countermeasure for urban warming, and therefore better understanding of the micro-climate benefits of urban green is needed. This study quantified the thermal influence of a large green park in Tokyo, Japan on the surrounding urban...

The relationship between long-term variations in summer temperature in Japan since the early 20th century and the large-scale atmospheric circulation field was analysed. The combined influence of various circulation predictors on temperature variations was analysed via a multicomponent canonical correlation analysis (CCA). The positive phase of the...

Climate variations in Tokyo based on reconstructed summer temperatures since the 18th century and instrumental meteorological data from the 19th century to the present are discussed. During the Little Ice Age, especially in the 18th century, remarkably cool episodes occurred in the 1730s, 1780s and 1830s. These cool conditions could be a significan...

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 s...

The long-term variability of the western edge of the North Pacific subtropical high (NPSH) and its relationship to summer temperature variability at 17 weather stations in Japan were investigated for the period from 1901 to 2000. Using the Hadley Center sea level pressure dataset (HadSLP2), we developed NPSH indices (NPSHIs) to describe both the zo...

In the present study, we estimated the winter temperature variations from 1830/31 to 2008/09 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 snowfall rate (percentage ratio of snowfall days to the...

To investigate the spatial and temporal variability of the urban heat island, a high-spatial density meteorological observation system was set up in the Tokyo ward area by Tokyo Metropolitan Research Institute for Environmental Protection (TMRIEP) and Tokyo Metropolitan University from July 2002 to March 2005. The observation system was named Meteo...

We analyze the influence of sea breeze on temperature distribution in the Kanto Plain (central Japan) on a day that a sea breeze front was detected (known as sea-breeze front days) using high-resolution temperature data observed by our research team. The high-temperature area on sea breeze front days moves northwest from central Tokyo, and was loca...

Synchronized kite-balloons measurements revealed the development of a nocturnal stable layer in an urban green park. The vertical structure of the park cool island is discussed. A stable layer developed in the park. In the surrounding urban area, neutral stratification was maintained all night. In spite of different weather conditions on the two ni...

This paper describes our newly developed high-resolution temperature observational system called Extended-METROS, which has been deployed in the Tokyo Metropolitan Area since 2006. Some climatological mean temperature charts using Extended-METROS data are analyzed in terms of urban climatology, and detailed urban heat island temperature patterns ar...

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 18years of pre-1881 data and a continuous series thereafter. The...

General circulation over East Asia and its linkages with sea surface temperature (SST) variability over the tropical Pacific is investigated for the 1958–2000 period. The western edge of the North Pacific subtropical high (NPSH) index (SHI) is defined from pentad 31 (May 31 to June 4) to pentad 49 (August 29 to September 2). A southwestward extensi...

An attempt was made to reconstruct winter climate conditions in Japan for the period 1810/1811 to 1858/1859 on the basis of daily weather records documented in old diaries. Daily weather maps for each winter were drawn using 19th century weather records collected by our research group. Maps were divided into five types by classifying daily snowfall...

The cooling effect of urban green area on the surrounding area has been studied by many researches. Some studies observed seeping-out phenomenon or park breeze where the cooled air in the park flows outward to all direction of urban area. But there have been few studies on the movement of cooled air inside the urban green area when of seeping out p...

The purpose of this study is to clarify the effects after the restoration of Cheonggye stream in Seoul, in order to pursue effective methods to mitigate the summer thermal stress in mega-city. The results of field observation in the summer of 2004 and 2007 summer showed that the stream-effect as a cooling source was confirmed. In the south of the s...

Synchronized kite balloon (kytoon) measurements in an urban park revealed the development of a nocturnal stable layer, which could mitigate urban heat island effects. A stable layer developed from the surface to 71 m above ground level in the park, although neutral stratification lasted throughout the night in the surrounding urban area. Calm, clea...

The urban heat island phenomena in summer over Tokyo Wards was studied by using the data obtained from METROS (Metropolitan Environmental Temperature and Rainfall Observation System), which is the high density heat island phenomena observation network. The observational results clarified the detailed spatial distributions of temperature never known...

The temperature and pressure differences between Tokyo and Nagasaki were applied for reconstruction of the past climate conditions. January and July in each year since the 1820's were divided into several types characterized by sea level pressure patterns. The findings indicated that the warming after 1900 (after the decline of the so-called Little...

On the basis of the pentad rainfall data averaged from 1961 to 2000, the seasonal march of rainfall in the Philippines is analyzed in this study. The relation to the atmospheric circulation at the 850 hPa level is also discussed. To investigate the temporal and spatial features of rainfall, the Empirical orthogonal function (EOF) analysis was appli...

Summary In this study, we have analyzed the temporal oscillations of precipitation in meso-scale zones of Sri Lanka to examine potential existence of periodic oscillatory behavior in rainfall. Only a few statistically significant cycles were identified: a 3.5-year cycle in most of central Sri Lanka during the January–March rainfall regime and a cyc...

This study examined the effects of heat island on the flowering dates of Prunus yedoensis in the wards of Tokyo in 2004. The main results were summarized as follows. 1) The distribution of the flowering dates of P. yedoensis corresponded well with the mean temperatures in March 2004. The flowering dates in the central urban area were earlier than t...

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 from Kobe covering the periods 1869–1871 and 1875–1888. The newly recovered records contain data...

日本の都市ヒートアイランド研究が大きく進展している．東京都心部の年平均気温は過去100年間に3°Cも上昇しており，地球平均気温の5倍の上昇率である．都市高温化の要因としては，第一に人工廃熱の増加による都市大気の直接加熱，第二に都市構造の変化，すなわち地表面の人工化や高層建造物の増加，緑地・水面の減少が挙げられる．最近行われた一連のプロジェクト研究から，都市内大規模緑地のクールアイランド効果や東京湾海風に及ぼす高層ビル群の影響，さらに高密度観測網による都内気温分布の日変化と海風による移流効果などが解明されつつある．今後のヒートアイランド問題の解明には，気候学をはじめ，気象学，建築・土木工学，医学，生態学など多くの分野における学際的な研究が不可欠である．

The cool island intensity（CII）on urban green space was investigated in Shinjyuku-Gyoen, that is one of the largest parks in Tokyo. A through-year measurement of ground level air temperature revealed seasonal variation and relationship to the atmospheric condition of CII. The temperature variation in the park and the reference downtown Tokyo was as...

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 from Kobe covering the periods 1869-1871 and 1875-1888. The newly recovered records contain data...

The present study documents daily and extreme precipitation over the Midwestern United States during El Niño months (WEM) and La Niña months (CEM) using station rainfall and the NCEP/NCAR reanalysis data for the period of 1987-1999 through U-test and composite analysis. The ENSO effect shows less of an influence on extreme precipitation when compar...

The so-called heat island phenomena found over large urban areas are thought to arise due to many causes; one of the major causes of the phenomena is direct heating of the lower atmospheric boundary layer by anthropogenic heat emissions. However, no quantitative assessment of this cause has been reported. Recently developed numerical regional meteo...

Urban Heat Island, a meteorological phenomenon by which the air temperature in an urban area increases beyond that in the suburbs, grows with the progress of urbanization. The difference of air temperatures between city center and suburbs is called Urban Heat Island Intensity (UHII). UHII is usually calculated as a fluctuation of the highest and lo...

The principal objective of this research is to clarify the mitigation effect of heat island and air pollution in Seoul city after the restoration of the Cheong-Gye Stream and green spaces which has been one of the main highway in Seoul. The authors are monitoring several meteorological parameters such as air temperature, humidity, wind speed/veloci...

A method to measure an area-averaged ground air temperature based on the hydrostatic equation is shown. The method was devised to overcome the problem of finding the most representative surface air temperature over a wide region, a problem that has seriously hindered the description of urban heat islands. The vertical pressure gradient is used and...

Green spaces in urban areas as well as water surfaces have been expected to mitigate the urban heat island effect. In the hot and humid summers in Japan, their cooling effect is especially valuable as a natural resource for city planning. In this paper, we show the results of micro-climatologic observations performed in and around the large park Sh...

An observational tower with 15 m high standing on Tokyo Metropolitan University has been providing basic meteorological data since March 1997. Data of air temperature, relative humidity, wind speed and direction, and solar radiation from January 2002 to December 2003 are reported in this paper.

The last 130 years of fluctuations in precipitation associated with the Southwest Monsoon (summer monsoon), Northeast Monsoon (winter monsoon), First Intermonsoon, and Second Intermonsoon seasons have been analysed at 15 climate stations in Sri Lanka. Analyses of trends in the interannual seasonal series indicated statistically significant temporal...

Daily rainfall data for 187 stations in Sri Lanka spanning the period 1960–1996 were analyzed to investigate the spatial and temporal characteristics of the mean rainfall intensity (MRI) through this time interval with special focus on the Southwest Monsoon (May–September). Particular emphasis was laid on temporal changes in the MRI series. The mea...

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 se...

The last 130 years of fluctuations in precipitation associated with the Southwest Monsoon (summer monsoon), Northeast Monsoon (winter monsoon), First Intermonsoon, and Second Intermonsoon seasons have been analysed at 15 climate stations in Sri Lanka. Analyses of trends in the interannual seasonal series indicated statistically significant temporal...

Ministry of Environment (MoE) has started making systematic counteractions against urban heat island (UHI) in Japanese regional autonomies regarding UHI as one of air pollution by heat. Nowadays a viewpoint of thermal environmental protection in urban planning process is still an unfamiliar concept for Japanese urban planners. But thermal stress in...

In order to reconstruct historical climate from daily weather records in old diaries, the method for estimating global solar radiation based on daily weather condition was constructed by Ichino et al. (2001). The most important variable in the formula is the mean daily clearness index (MDCI), which is a quantitative measure of weather condition. Th...

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...

A study of the seasonal structure of rainfall organization in a humid tropical mountain region of West Africa using multivariate classification techniques revealed considerable variations in rainfall regimes from ultra-humid to sub-humid conditions. Principal Component Analysis produced a three-component model which was used to characterize and exp...

1. INTRODUCTION Green space in urban area have been expected to mitigate the urban heat island as well as water surface. In Japan, its cooling effect in hot and humid summer is especially important and it is considered as a natural resource to be available for city planning. In this paper, we show the results of micro-climatological observations pe...

Urban heat island (UHI) phenomenon, as an important environmental issue affecting cities, has received much attentions in the past decades. The spatial structure of UHI, however, is not easy to verify in detail because of the complexity of its mechanism and cost of observations. Many researchers have studied this issue with satellite sensed thermal...

A thermal property parameter for expressing the ground heat flux (cpλ; product of the heat capacity and the thermal conductivity) of urban complex terrain was estimated. The surface temperature time series was observed during nocturnal radiative cooling, and employed in the estimation. The surface temperature was obtained using the airborne-measure...

We examined a hydrothermal structure of the atmosphere on the mountain slope during clear calm nights at southern slope area of Mt. Yatsugatake, central Japan. An observation was carried out in November, 1993 using various meteorological observation methods such as ground surface observations with thermometers and a thermography, and kite-balloon o...

In order to examine the usefulness of thermal images in analysis of thermal belt formation, eleven nocturnal LANDSAT/ TM thermal images of the southern slope of Mt. Akagi at the northern edge of Kanto Plain in central Japan were analyzed. Nine images have the higher LST (land surface temperature) on the mid-slope, which is always accompanied with L...

An observational tower standing on Tokyo Metropolitan University campus has been providing basic meteorological data needed for the satellite remote sensing analysis since April 1997. We will report the characteristics of observed data in terms of seasonal changes of several meteorological elements which are crucial for the energy balance component...

Interannual variations of summer rainfall over Asia and their associations with geopotential heights in the Northern Hemisphere, tropical convective activities and global sea surface temperature (SST) anomalies are investigated. The Empirical Orthogonal Function (EOF) analysis is applied to the summer rainfall data (JJAS) at 220 stations from 1951...

The observation was carried out in Nagahama-city, Shiga-prefecture for two days in the end of July, 1996. Starting from the shore of a lake, in the section of about 3800m to an edge of urban district, we set a self-registering thermometer at nine points along the prefectual road that was vertical to the shore of a lake, and air temperatures were co...

In the beginning of August, 1997 under typical summer pressure patterns, we observed an intensive observation. Using the portable thermal infrared camera, thermal infrared images were taken from Meijishrine/Yoyogi-park of Tokyo that was a large-scale green tract, and its peripheral area. The thermal infrared camera was setted by 1 on top of the Tok...

High negative correlation between summer rainfall anomaly in the Yangtze Valley and the middle reaches of the Yellow River in China is shown. Rainfall Anomaly Index (RAT) and the Student's t-test revealed a decadal fluctuation of RAT in the Yangtze Valley at the end of the 1970s. The results concerning correlation between RAT and atmospheric circul...

The relationships between the summer (June to September) rainfall variability in South and East Asia and the sea level pressure (SLP) field in the tropics are clarified both by principal component analysis (PCA) and by singular value decomposition analysis (SVDA). First, we applied PCA to summer rainfall for detecting temporal and spatial variation...

High negative correlation between summer rainfall anomaly in the Yangtze Valley and the middle reaches of the Yellow River in China is shown. Rainfall Anomaly Index (RAT) and the Student's t-test revealed a decadal fluctuation of RAT in the Yangtze Valley at the end of the 1970s. The results concerning correlation between RAT and atmospheric circul...

We examined a thermal structure on the mountain slope over clean calm nights at the southern Mt. Yatsugatake, central Japan. Meteorological observations showed double thermal inversions over the slope. The upper one appeared between approximately 1800 m and 2000 m a.s.l. (1100 m and 1300 m from surface), and the lower one, between 700 m and 950 m a...