This study aimed to understand the characteristics of transnational migrants and their behaviors in global cities using the examples of three Koreatowns in the New York metropolitan area. The fieldwork conducted in 2012 and 2013 was based on qualitative research methods such as participant observation in Korean church communities and in-depth interviews with 42 migrants selected by snowball sampling. The results suggested the following two conclusions.

First, Korean immigrants in the New York area can be classified into two groups, old-timers and newcomers, who migrated at different times and show contrasting characteristics. While old-timers in New York comprises permanent residents who settled by the end of the 1980s and have run ethnic businesses for decades, the newcomers are young, well-educated transmigrants who arrived in New York after the 1990s as a global city to start professional careers.

Second, behavioral differences can be seen between old-timers and newcomers in terms of residence location and use of Koreatowns, which caused the formation of various types of Koreatowns in the New York metropolitan area. Old-timers, who are deeply dependent on the Korean community, relocated from the inner city to suburbs forming Koreatowns in each area including residential and commercial functions. On the other hand, newcomers’ places of residence are dispersed and they visit the Koreatown in Manhattan as a center of Korean human networks and an ethnic commercial district.

These aspects are the results of political and economic phenomena, including the paradigm shift to neoliberalism, changes in the US immigration policy, and economic progress in newly developing countries. These phenomena changed the characteristics of migrants to global cities, which influenced the formation of ethnic enclaves in urban areas.

We investigated nocturnal vertical potential temperature profiles under clear and weak wind conditions in central urban Tokyo, Japan, using air temperature data from 2001 to 2010 observed at five heights (4, 64, 169, 205, and 250m) at Tokyo Tower. Although the surface layer vertical potential temperature profile was expected to be neutral under strong wind conditions, the potential temperature based on the dry adiabatic lapse rate at a specific height was about 0.5°C higher than at other heights in the top 2% of wind speeds. In this study, we statistically corrected potential temperature at each height, assuming that the vertical potential temperature profile becomes neutral with sufficiently strong winds.

Cluster analysis was applied to the potential temperature gradient vertical distribution below 250m each hour from 18:00 Japanese Standard Time (JST) to 8:00 JST the next day under clear and weak wind speed conditions. We separated the temperature distribution into five categories. Atmospheric stability was neutral from the surface to the upper layer in cluster A and stable below and neutral above 64m in cluster B. Atmospheric stability was weakly stable from the surface to the upper layer in cluster C, stable from the surface to the upper layer in cluster D, and extremely stable from 205m to the upper layer and weakly stable below 205m in cluster E. From November to February, cluster D and E frequency increased before midnight, with the highest frequency at around sunrise. On the contrary, neither cluster D nor E appeared at all from May to August. The extremely stable layer in cluster E is thought to be the stable layer base over the urban area. The nocturnal mixing layer height was about 200m or above in winter, and the ratio of its height and average building height around Tokyo Tower was greater than in other cities. The increase in stable layer base height compared with that observed in the 1960s can be attributed to verticalization in central Tokyo. In addition, it was suggested that enhancement or restraint of vertical mixing and vertical displacement of the stable layer base contribute to temporal transitions in the vertical potential temperature profile at night.

We carried out ground-penetrating radar (GPR) soundings and geodetic surveys in four perennial snow patches in the northern Japanese Alps and considered the possibility that they were active glaciers. The Kakunezato and Ikenotan perennial snow patches had large ice masses (>30m thick), and the ice masses had flowed for more than 2m/a. Hence, we regarded both snow patches as active glaciers. Since the Kuranosuke perennial snow patch also had a large ice mass (25m thick) and the ice mass had flowed only 3cm/a, we regarded the snow patch as an active glacier that had been transforming into a perennial snow patch. The Hamaguriyuki perennial snow patch was not considered to be a glacier because it exhibits no flow at present.

We also examined the climate conditions, mass balance, and surface area changes of active glaciers in the northern Japanese Alps based on field measurement data. The climate conditions in the alpine zone in the Tateyama Mountains, the northern part of the northern Japanese Alps, were similar to those at the equilibrium-line altitude (ELA) of the Nisqually Glacier, Cascade Range, USA. This indicates that active glaciers could form and be preserved under the current climatic conditions in the Tateyama Mountains. Since there was a difference of more than 900m in the ELA between the Kuranosuke and Kakunezato perennial snow patches (glaciers), the ELAs of the glaciers in this region are likely to vary greatly in the narrow region. The Kakunezato and Ikenotan perennial snow patches (glaciers) lost only 12% and 16% of their surface areas between 1955 and 2016, respectively. Hence, the recent retreat of the glaciers in this region should be slow.

Severe debris flows caused by a localized torrential downpour, attacked residential areas in the outskirt of Hiroshima City before the dawn on August 20, 2014. Seventy-four people caught by the debris flows were killed. Houses of the victims were commonly located on gentle slopes formed by older debris flows at the foot of mountains. The area called as Yagi-sanchome was most heavily damaged by the debris flows, and forty-one people lost their lives. Many reports described that sprawling of residential area during the period of high economic growth (1955–1973) in the post-WWII period of Japan, could be one of the reasons for the severe damage.

We identified construction period of the houses in Yagi-sanchome based on photogrammetric analysis of aerial photographs taken six times since 1947, and counted the number of houses built during each period. For easier and more efficient identification of houses built between consequent periods, we carried out a residual analysis of digital surface model (DSM) processed by Structure-from-Motion (SfM) software using aerial photographs.

We also counted numbers of the houses in the debris flow area, and the demolished houses by debris flow, and the houses victims lived. The results showed that the ratio of demolished houses and houses victims lived were higher among the houses built after the economic growth period than those built during the period.

Photographs taken by unmanned aerial vehicle (UAV) taken before after the debris occurred in Yagi-sanchome by one of the authors, reveals one of the typical examples of human neglect of potential debris flow hazards that resulted in unnecessary loss lives.

The purposes of this paper were to clarify the backgrounds of internal structure models of US cities proposed around the World War II period, i.e., Hommer Hoyt’s sector model and Chauncy Harris and Edward Ullman’s multiple nuclei model, and to examine the changes occurring after the war in this research area. The author not only analyzed papers and books on Hoyt, Harris, and Ullman, but also followed their careers because they engaged in nonacademic work such as business and wartime service during the era of the Great Depression and World War II.

Hoyt joined the Federal Housing Administration (FHA) soon after acquiring his Ph.D. in 1934 with a doctoral dissertation titled “One hundred years of land values in Chicago.” One of the most important tasks of the FHA was to establish a highly stable mortgage system. For this purpose, Hoyt and his colleagues, as FHA researchers, analyzed huge amounts of data collected from several land-use surveys conducted by the Works Progress Administration. Using those research results, Hoyt crystallized his sector model.

Both Harris and Ullman followed the typical careers of academic geographers, but they also served in the military during World War II. Harold Mayer, a good friend from their graduate student years and another famous Chicago urban geographer, also seemed to have made critical contributions to their paper titled “The nature of cities,” describing their multiple nuclei model. Mayer served as a research planner for the Chicago Planning Commission under the directorship of Hoyt. During this period, Mayer gained considerable knowledge and learned many research skills from Hoyt and other land economists and urban planners.

Next, the author examined Eshref Shevky and Wendy Bell’s social area analysis, the first epochmaking postwar work in this field, to identify what changes the end of the war brought to research in this area. Their research methods were applicable to many US cities for which census tract (CT) statistics were available. CT statistics were produced as early as 1910, but it was only after the 1940 census that the US federal government assumed responsibility for producing CT statistics for major cities. Their study marked an important landmark in clearing various research constraints during World War II.

The findings of this study illustrate the importance of nonacademic practices for research developments in US urban studies around the World War II period. Later, Hoyt and Mayer enthusiastically promoted effective cooperation and codevelopment between the nonadacemic and academic worlds.

Population censuses are the only surveys that have been conducted for all residents across Japan, and the data have often been used in geographic studies for creating sociodemographic indices at the neighborhood level (cho-cho aza). However, there have been concerns about the increase in “not reported” cases in recent population censuses, which are nonresponses due to a refusal to complete the survey. In this study, we aimed to: 1) examine geographical patterns of the not reported cases at the small area level; 2) discuss their influence on regional analysis; and 3) explore some ways to deal with this problem. Using the 2010 population census, percentages of not reported cases were calculated for the five variables of age, marital status, labor force status, education, and past residence that have been repeatedly used in geographic studies. We then aggregated the percentages of not reported cases by the degree of urbanization on multiple scales and visualized their geographic distribution using maps. Finally, multilevel negative binominal regression models were used to estimate incidence rate ratios of the number of not reported cases in neighborhoods using the degree of urbanization on multiple scales as independent variables and municipalities as a group variable. The results showed that there were clear urban–rural gradients in the distribution of the not reported cases, with the highest percentages in urban areas and the lowest in rural areas. We also found significant municipality-level variance (spatial clustering) in the not reported cases as a result of the multilevel analysis. This may suggest that the survey methods and resources utilized by municipalities, which are in charge of conducting census surveys, could influence the survey responses of residents and potentially introduce systematic errors into the data. These results emphasize the necessity of taking into account the bias caused by the not reported cases when conducting small area analysis using population censuses. Exploring the determinants of the not reported cases by conducting social surveys independently from the census as well as considering statistical methods of adjustment for the missing cases are also required.