Daytime Populations Research Articles

Daily Diversity Flows: Racial and Ethnic Context Between Home and Work.

The racial and ethnic diversification of the U.S. population has transformed the demographic makeup of communities and rapidly increased exposure to diversity in American neighborhoods. Although diversity exposure occurs throughout people's daily lives, the conventional approach to describing diversity only at places of residence potentially understates the full extent of this phenomenon. In this study, we explore short-term, within-day changes in the diversity of different neighborhoods by considering U.S. workers' work and residential locations. Using estimates for daytime and nighttime populations among metropolitan census tracts, our empirical analyses investigate the extent to which the process of daytime mobility for work relates to changes in the racial and ethnic diversity of different spaces. Our results indicate widespread daily shifts toward diversity for most neighborhood types, especially those with residential (nighttime) populations that are predominantly Black, Latino, or Asian. We find that patterns of intraday diversification experienced minor declines across recent decades but are present in most metropolitan areas. Our findings also show that intraday changes in racial and ethnic diversity overlap with nonracial forms of daily diversity change. Further, average within-day changes in diversity are more pronounced in areas with greater residential segregation.

Using heat map data to measure population development trends and urban disparities of large-scale affordable communities in China

Over the past decade, large-scale affordable communities have proliferated in the suburban areas of major Chinese cities. Most of the housing in these communities consists of affordable housing provided by the government and constructed by developers, targeted at middle to low-income individuals through restricted-price sales and rentals. With more than a decade of occupancy, it is crucial to examine the development status of these communities. This study employs regular collection of heat map data to observe the population density trends in communities from 2020 to 2024. By analyzing population density and its derived variables, the study examines changes in daytime and nighttime populations during weekdays, as well as the differences between the Spring Festival period and regular population data. Combining urban context, we use both quantitative and qualitative methods to analyze population quantity and structure trends and further explore the development disparities among cities. The study reveals a widespread increase in population across 35 communities in five cities from 2020 to 2021, peaking in 2021 and 2022, with differentiation among cities after 2023. Before 2022, there was a pattern in the development of community population quantity and structure: communities with faster population growth exhibited a simultaneous increase in commuter proportions. The impetus for community population changes is largely attributed to the varying attractiveness of cities to the floating population, with the five cities demonstrating distinct patterns. The method used in this study to collect population data, as opposed to traditional questionnaire surveys, presents advantages in terms of real-time, efficiency, convenience, and high sensitivity. This approach can offer feasible insights for establishing a real-time monitoring system for the development of large-scale affordable communities in China in the future.

Methodology to incorporate seismic damage and debris to evaluate strategies to reduce life safety risk for multi-hazard earthquake and tsunami

This paper presents a methodology to evaluate life safety risk of coastal communities vulnerable to seismic and tsunami hazards. The work explicitly incorporates two important aspects in tsunami evacuation modeling: (1) the effect of earthquake-induced damage to buildings on building egress time, (2) the effect of earthquake-induced debris on horizontal evacuation time. The city of Seaside, Oregon, is selected as a testbed community. The hazard is based on a megathrust earthquake and tsunami from the Cascadia Subduction Zone that was defined in a previous study. The built environment consists of buildings and the transportation network for the city. Fragility analysis is used to estimate the seismic damage to buildings and resulting debris that covers portions of the road network. The horizontal evacuation time is determined based on the shortest path to shelters, including the increased travel time due to the earthquake-generated debris. The effects of different mitigation strategies are quantified. Results indicate the fatality and life safety risk of a near-field tsunami increases by 4.2–8.3 times when the effects of building egress and earthquake-induced debris are considered. The choice of population layer affects the life safety risk and thus the maximum risk is obtained when daytime populations are considered. Use of mitigation strategies result in a significant decrease in the number of fatalities. For hazards with recurrence intervals larger than 500- to 1000-years, the seismic retrofit is comparable to vertical evacuation and an effective strategy in reducing fatalities and associated risks. Implementing all mitigation strategies reduces the life safety risk by 90%.

Working from home in Australian cities as a catalyst for place-making?

ABSTRACT As more people work from home, the distribution of daytime populations will change across cities. This will lead to some households relocating, as well as a redistribution of the places of congregation and consumption. This paper analyses changes of population distribution based on occupations that can be worked from home, the spatial distribution of the suitability of housing, and access to amenity and services. The method applied is geo-spatial, mapped to local government areas across Sydney, Australia’s largest city. The redistribution of populations indicates a potential rationalisation of CBD environments but also shows opportunities for local governments to embrace middle and outer suburb regeneration, as well as strategic planning opportunities to capitalise on the higher levels of foot-traffic. We argue that with adapted urban planning and design, and if appropriate infrastructure investments are made, then WFH practices are likely to lead to beneficial sustainability and equity outcomes.

Working from Home as a Catalyst for Urban Regeneration

Since the COVID-19 pandemic, working from home has become normalised and is likely to continue to gather pace. The adjustment in daytime population that this creates has implications for urban planning, as it can drive greater levels of localization and less car-dependent cities. In this paper, we describe how this shift changes urban daytime population density, a significant predictor of most measures of amenity, walkability, and liveability. First, we define a method for mapping access to amenity, applied to two cities: Melbourne and Sydney. Secondly, we analyse the two-way causal relationship between population density and amenity based on bivariate spatial mapping. Thirdly, we provide a method for estimating changes in daytime populations. Finally, the article provides a taxonomy of telework regeneration potential for different parts of the city based on the level of amenity and expected changes in daytime population (average changes in high job-density areas −14%, CBDs −30%, and +54% in residential areas). We argue that, if used as a catalyst within strategic planning, and for urban regeneration, increases could create higher levels of amenity in suburban areas, which can lead to improved sustainability outcomes, specifically greater levels of walkability, liveability, and reduced car dependence. We have calculated that opportunity areas account for 89% of the greater urban area and cover 49% of the population, which may well grow as the WFH trend continues. As such, and in conclusion, we outline a set of site-specific opportunities and challenges relevant to urban planners that aim for urban regeneration.

Relationship between Urban Three-Dimensional Spatial Structure and Population Distribution: A Case Study of Kunming’s Main Urban District, China

The three-dimensional (3D) spatial structure within cities can reveal more information about land development than the two-dimensional spatial structure. Studying the relationship between the urban 3D spatial structure and the population distribution is a crucial aspect of the relationship between people and land within cities. However, a few relevant studies focus on the differences between employment population and night population distribution in relation to urban 3D spatial structure. Therefore, this study proposes a new concept of 3D space-filling degree (3DSFD), which is applicable to evaluate the city’s 3D spatial structure. We took 439 blocks in Kunming’s Main Urban District as a sample and analyzed the 3D spatial structure based on geographic information data at the scale of a single building. The characteristics and differences of the daytime and night population distribution in Kunming’s Main Urban District were identified using cell phone signaling big data. Accordingly, a cross-sectional dataset of the relationship between the city’s 3D spatial structure and the population distribution was constructed, with the 3D space-filling degree of the block as the dependent variable, two indicators of population distribution (daytime and night population density) as the explanatory variables, and seven indicators of distance from the city center, and building, road, and functional place densities, proportion of undevelopable land area, housing prices, and land use type as the control variables. We used spatial regression models to explore the significance, strength, and direction of the relationship between urban 3D spatial structure and population distribution. We found that the spatial error model (SEM) was the most effective. The results show that only night population distribution is significantly and positively related to 3DSFD. Every 1% increase in night population density in a block will increase the value of 3DSFD by 2.8307%. The night population distribution is the core factor affecting the 3D spatial structure of Kunming’s Main Urban District. The correlation between daytime population distribution and 3DSFD is not significant. This variability has been ignored in previous studies. The findings are informative for further understanding of the relationship between urban 3D space and population distribution, especially the difference between night and daytime populations. This study can help city managers reasonably plan urban land development intensity and construction height, guide the population layout and formulate management policies to improve urban population and space matching, enhancing the livability and attractiveness of cities.

Visualizing Social and Behavior Change due to the Outbreak of COVID-19 Using Mobile Phone Location Data

We visualize the rates of stay-home for residents by region using the difference between day-time and night-time populations to detect residential areas, and then observing the numbers of people leaving residential areas. There are issues with measuring stay-home rates by observing numbers of people visiting downtown areas, such as central urban shopping centers and major train stations. The first is that we cannot eliminate the possibility that people will avoid areas being observed and go to other areas. The second is that for people visiting downtown areas, we cannot know where they reside. These issues can be resolved if we quantify the degree of stay-home using the number of people leaving residential areas. There are significant differences in stay-home levels by region throughout Japan. By this visualization, residents of each region can see whether their level of stay-home is adequate or not, and this can provide incentive toward compliance suited to the residents of the region.

Effect of population inflow and outflow between rural and urban areas on regional antimicrobial use surveillance.

Regional-level measures can complement national antimicrobial stewardship programs. In Japan, sub-prefectural regions called secondary medical areas (SMAs) provide general inpatient care within their borders, and regional antimicrobial stewardship measures are frequently implemented at this level. There is therefore a need to conduct antimicrobial use (AMU) surveillance at this level to ascertain antimicrobial consumption. However, AMU estimates are generally standardized to residence-based nighttime populations, which do not account for population mobility across regional borders. We examined the impact of population in/outflow on SMA-level AMU estimates by comparing the differences between standardization using daytime and nighttime populations. We obtained AMU information from the National Database of Health Insurance Claims and Specific Health Checkups of Japan. AMU was quantified at the prefectural and SMA levels using the number of defined daily doses (DDDs) divided by (a) 1,000 nighttime population per day or (b) 1,000 daytime population per day. We identified and characterized the discrepancies between the two types of estimates at the prefectural and SMA levels. The national AMU was 17.21 DDDs per 1,000 population per day. The mean (95% confidence interval) prefectural-level DDDs per 1,000 nighttime and daytime population per day were 17.27 (14.10, 20.44) and 17.41 (14.30, 20.53), respectively. The mean (95% confidence interval) SMA-level DDDs per 1,000 nighttime and daytime population per day were 16.12 (9.84, 22.41) and 16.41 (10.57, 22.26), respectively. The nighttime population-standardized estimates were generally higher than the daytime population-standardized estimates in urban areas, but lower in the adjacent suburbs. Large differences were observed in the main metropolitan hubs in eastern and western Japan. Regional-level AMU estimates, especially of smaller regions such as SMAs, are susceptible to the use of different populations for standardization. This finding indicates that AMU standardization based on population values is not suitable for AMU estimates in small regions.

A trip to work: Estimation of origin and destination of commuting patterns in the main metropolitan regions of Haiti using CDR

The rapid, unplanned urbanisation in Haiti creates a series of urban mobility challenges which can contribute to job market fragmentation and decrease the quality of life in the city. Data on population and job distributions, and on home-work commuting patterns in major urban centres are scarce. The most recent census took place in 2003 and events such as the 2010 earthquake have caused major redistributions of the population. In this data scarce context, our work takes advantage of nationwide de-identified Call Detail Records (CDR) from the main mobile operator in the country to investigate night and daytime populations densities and commuting patterns. We use a non-supervised learning algorithm to identify meaningful locations for individuals. These locations are then labelled according to a scoring criteria. The labelled locations are distributed in a grid with cells measuring 500 × 500 m in order to aggregate the individual level data and to create origin-destination matrices of weighted connections between home and work locations. The results suggest that labor markets are fragmented in Haiti. The two main urban centres, Port-au-Prince and Cap-Haïtien suffer from low employment accessibility as measured by the percentage of the population that travels beyond their identified home cluster (1 km radius) during the day. The data from the origin-destination matrices suggest that only 42 and 40 percent of the population are considered to be commuters in Port-au-Prince and Cap-Haïtien respectively.

Space-time Clusters of Crime in Stockholm, Sweden

The aim of the study is to detect geographical clustering of offences over time using Kulldorff’s scan test (SaTScan version 9.01; Kulldorff, 2010) and police recorded data over Stockholm city, the capital of Sweden. This technique has a rigorous inference theory for identifying statistically significant clusters. The space–time scan statistics are used in a single retrospective analysis using data from 1st January 2006 to 31st December 2009. A four years’ dataset is collapsed into ‘one year’. All space-time dimensions of the data are kept except ‘year’. Clusters over the hours of the day, weekday and weekend and by seasons were tested. Total population but also day-time and night-time populations were used as reference. Findings show clear distinct patterns of concentration for violence (assault and threat) and property crimes (theft, robbery and burglary) over time and space. Whilst property crimes tend to happen more often in the afternoons in the center and regional commercial centers in the southern and western parts of Stockholm, violence takes place more often in the night, and is heavily concentrated in large parts of the city center. Weekends are more targeted than weekdays for both offences. Regardless of day of the week, the main urban core of the city contains the most likely cluster that extends to commercial and socially disorganized areas in the west and south Stockholm. Whilst property crime levels do not show significant differences over the seasons, violent crimes levels do (winter and summer). The most likely clusters tend to be fairly constant in space over time. The article ends with implications of the results for both research and practice.

Discrete choice in commuter space: Small area analysis of diurnal population change in the Tokyo Metropolitan Region

Considerations of metropolitan commuting have often related to urban space as a continuum, and to commuting itself as a process. This approach has led to escalating complexity in the measurement, modeling and analysis of commuting, often with no commensurate results. The present study extends an alternative approach that considers commuter space of a metropolis as a discrete set of small areas. Each small area throughout the metropolis is a nighttime location of some households and, as a possible discrete destination choice of individuals within households, each subarea is also a daytime location of some persons. Each subarea, therefore, may be thought of as attaining two values, corresponding to its daytime (e.g., noontime) and nighttime (e.g., midnight) populations. The diurnal demographic shift of subareas, as a set of binary events, or toggles, between daytime and nighttime populations, is associated with commuter access throughout the metropolis. Diurnal shift offers structural simplicity aimed at estimating small-area daytime populations across a metropolitan region that might suitably precede and complement conventional continuum considerations of commuting. Using data for the Tokyo Metropolitan Region, we identify average household size as the nighttime indicator of small-areas, and daytime population density as their daytime indicator. The potential for the estimation of daytime populations across metropolitan regions where daytime population data are unavailable, is underscored by the clear tendency towards inverse relation of these two indicators of diurnal shift.

Urban Commuting and Daytime Population in Small Areas of a Metropolis:A Case Study of Brno, Czech Republic

A simplified modelling approach to urban commuting patterns is achieved by focusing on daytime populations rather than on commuters, or on the commuting process itself. Whereas past studies were usually economic in nature, and viewed commuting as a process within the continuum of urban space and time, the approach addressing daytime populations transforms the modelling attempt into a demographic deliberation of a binary situation where switching of values between daytime and night-time indicators in each subarea throughout a metropolis is considered. The present study shows that such a focus on diurnal change as a binary concept offers a new paradigm in conceptualizing metropolitan commuting and transportation. Under certain assumptions, rooted in recent observations of metropolitan areas elsewhere, this study conjectures an analytic function for the estimation of daytime populations in small areas throughout the metropolitan region of Brno, Czech Republic. The conjectured relationship is a logistic function that utilizes as its independent variable the average household size in each of the subareas throughout the metropolitan region. Based on the data from the Czech census of 2001, the distributions of average household size and of residential populations throughout the metropolitan region are applied in a case study illustrating the utility of the proposed approach for the estimation of daytime populations throughout the region. The iterative procedure advanced here offers considerable potential for further applications elsewhere. KEY WORDS: metropolitan commuting, urban transportation, Brno, daytime population, average household size, logistic function, small area demography

Opening a larger window onto forest elephant ecology

AbstractAfrican forest elephants (Loxodonta cyclotis) can be observed reliably in forest clearings but are difficult to observe directly in their otherwise forested habitat. To obtain data on population demography and activity cycles, conservation programmes commit considerable human and financial resources to observations at clearings. However, individual elephants spend only a tiny proportion of their annual activity budget in a particular clearing, and there may be demographic differences between daytime and nighttime populations. Using acoustic monitoring tools to assess elephant numbers continuously for long time periods at multiple clearings, we show that daytime‐only observations are likely to be biased. In this study, (i) 79% of all elephant visitation occurred at night, (ii) sometimes large changes in nocturnal elephant numbers occurred without proportional changes in daytime elephant numbers, and (iii) there were indications that a different demographic of the population visits clearings at night compared with the day. These results suggest that acoustic monitoring should be incorporated into forest elephant monitoring programmes to augment direct observation and that more study is needed to explicitly identify any biases inherent in daytime‐only observation.

The origin-destination matrix as an indicator of intrahousehold travel allocation

Subareas throughout a city may be viewed as both daytime destinations for some persons as well as residence (or nighttime) locations for some households. Associated with the average household in each subarea is the distribution of its members by their daytime destinations. Travel allocation of individuals by their principal subarea of daytime destination can be thus constructed for the average household in each subarea throughout a city. Intrahousehold allocation of daytime destinations can thus be represented in a convenient tabular form, the household composition matrix. Further interpretation shows the household composition matrix to be a special case of an origin-destination (O-D) matrix representing commuter volumes between subareas of nighttime and daytime location. Formal features of the household composition matrix, furthermore, render it equivalent to the Leontief input-output matrix. The relationship between intrahousehold travel allocation and household composition, as an O-D matrix, emerges to be of particular importance within the context of Leontief's input-output concept. Application to the Seoul Metropolitan Area indicates a discernable pattern in intrahousehold travel allocation when ordering of the household composition matrix is based on ratios between daytime and nighttime populations across the city's subareas.

Non-LTE Infrared Emissions of CO 2 in the Atmosphere of Venus

A non-local thermodynamic equilibrium (non-LTE) radiative transfer model previously developed for the martian atmosphere has been applied to the venusian atmosphere to study the CO 2 infrared emissions and its radiative equilibrium temperature profile. The model computes the populations of more than 60 vibrational levels of the four major isotopes of CO 2, and the cooling and heating rates by more than 90 radiative transitions. The departure from LTE of all the CO 2(0,ν 2,0) levels is found to occur around 115 km (or 0.2 μb) during both night and daytime conditions, while it takes place around 105 and 90 km for the (0,0,1) level at night and day, respectively. The daytime populations of the (ν 1,ν 2,1) and high combination levels are very large. The cooling rate due to the 15-μm bands peaks around 125 km (10 nb) and amounts to 130 K/day for the reference nighttime model, being very dependent on the thermal structure. The 15-μm fundamental bands (FB) of the minor isotopes and the first hot bands of the major isotope produce much greater cooling than the FB of the main isotope between 110 and 125 km. The solar heating rate presents a double peak maximum between 120 and 135 km, with a very strong component from the 2.7-μm FB around 130 km. This component is much more important than its martian counterpart, due to the larger relative abundance of atomic oxygen in the thermosphere of Venus. The rate coefficient for collisional activation of CO 2(ν 2) by atomic oxygen used in this work, 3×10 −12cm 3 s −1, coincides with the value currently recommended for the Mars' and Earth's upper atmospheres, although a definitive measurement of this important rate remains to be carried out in the laboratory. Radiative relaxation times have been computed with focus on the 80–130 km region. The relaxation at 15 μm varies from more than an Earth's week around 80 km to a minimum of 6 min around 130 km during daytime. It increases above this altitude, in clear contrast to LTE calculations. Sensitivity studies to evaluate the effects of the current uncertainties in the major rate coefficients and comparisons with previous non-LTE models and data, as well as with similar situations in the atmosphere of Mars, are presented.

Comparison of Daytime and Night-Time Populations Adjacent to Interstate Highways in Metropolitan Areas

AbstractDaytime and night-time population densities bordering Interstate highway routes in metropolitan areas are compared at the traffic analysis zone level. In three of the metropolitan areas studied, histograms of daytime to night-time population density ratios are peaked at 1.0. In a smaller metropolitan area, the peak of the histogram moves to values greater than 1.0 but less than 2.0. In view of the typical uncertainties in calculating radiological transport effects (∼2), this study indicates that a distinction between daytime and night-time transport is not warranted, especially since a typical route includes extensive transport outside metropolitan areas.

On the accuracy of the limb sounding of the atmosphere in the 10.4 μm, 15 μm CO 2 and 9.6 μm O 3 bands with account for non-LTE

Inverse problem of thermal radiation transfer accounting for non-LTE effects has been considered for limb geometry in the spectral region covering 10.4μm, 15μm CO 2 and 9.6μm O 3 bands. Limb radiance has been calculated line-by-line on the basis of the non-LTE model describing day-time non-equilibrium populations of the vibrational states of CO 2 and O 3 molecules which correspond to the bands under consideration. The inverse problem for the satellite limb radiance high resolution measurements in the spectral interval 540–1150 cm −1 has been posed with respect to the simultaneous retrieval of the vertical profiles of pressure, kinetic temperature, number density of main absorbers, and vibrational temperatures of the states mentioned above. For the estimation of the retrieval accuracy the optimal estimation method has been applied, and the calculations of error matrices have been performed. The influence of the spectral resolution of measurements on the retrieval accuracy has been investigated. The conclusion has been done on the applicability of measurements to be performed in future by instruments similar to MIPAS to the investigations of non-LTE effects in the middle atmosphere.

A non‐local thermodynamic equilibrium radiative transfer model for infrared emissions in the atmosphere of Mars: 2. Daytime populations of vibrational levels

A non‐local thermodynamic equilibrium (LTE) radiative transfer model has been applied to study the CO2 and CO emissions in the infrared (1–20 μm) in the atmosphere of Mars during daytime conditions. An extensive set of vibrational‐translational (V‐T) and vibrational‐vibrational (V‐V) collisional exchanges among the vibrational levels responsible for these emissions has been considered. Radiative transfer has been included for most of the transitions and its importance illustrated for some of them. The populations of the most important vibrational levels of GO and of the ν2 and ν3 modes of CO2 are presented. The CO2(0,ν2,0) levels follow LTE up to about 80 km at daytime, some 5 km lower than at nighttime conditions. The absorption of solar radiation at 1.6, 2.0, and 2.7 μm, and subsequent relaxation by V‐V and radiative processes, significantly populates these levels in the lower thermosphere, increasing all their vibrational temperatures with respect to nighttime conditions. Solar excitation and radiative transfer in 4.3 μm constitute the main sources of excitation of the (0,0°,1) level in the thermosphere, where this level shows a very large vibrational temperature. The V‐V transfer from highly excited CO2 levels is even larger than the direct radiative excitation of the (0,0°,1) level in the mesosphere. The model predicts that the known inversion population between this vibrational level and the lower (0,2°,0) and (1,0°,0) levels will occur in the high mesosphere and above. The CO(1) level also shows much larger populations than during nighttime conditions, due to direct solar absorption at 4.7 μm and the role played by radiative transfer. A sensitivity study of the effect of current uncertainties in rate constants on the level populations is also presented. The uncertainties in the rate for ν3 quanta exchange among CO2 levels have significant effects on the deactivation of high energy states, leading to changes of importance in the daytime populations of the 2.7‐μm states in the mesosphere and in the (0,0°,1) level in the lower thermosphere.

Nighttime and Daytime Populations of Large American Suburbs

Nighttime and Daytime Populations of Large American Suburbs

Estimating Daytime Populations

(1956). Estimating Daytime Populations. Journal of the American Institute of Planners: Vol. 22, No. 2, pp. 83-85.