Research On Population Mobility In Liaoning Province Based On Nighttime Light Data

The problem of population is one of the important matters in today's society.With the continuous development of urbanization,more and more people choose to work and live in cities,thus the population flow statistics has become a hot research content.The method of extracting population data based on the old night light data is not high in spatial resolution,which is difficult to reflect the actual situation of population distribution in the urban built-up area,and the spatial visualization analysis and application accuracy of population data are limited.Compared with DMSP / OLS nighttime lighting data,NPP-VIIRS nighttime lighting data,as the latest nighttime lighting data,contains the basic characteristics of DMSP / OLS nighttime lighting data,and improves the resolution to 500 m.It also includes daily data,monthly composite data and annual composite data in the time span,which provides a new way for studying population flow based on nighttime lighting data Basics.Therefore,it is of great practical significance to improve the spatial resolution of population migration and refine the research time unit with NPP-VIIRS nighttime lighting data.This paper takes Liaoning Province as the research object,fully considering the characteristics of the source data,selects the NPP-VIIRS night light data from April2012 to April 2019(excluding May,June and July of each year).In this paper,the threshold method is used to extract the built-up areas of 14 cities,and a linear model is established based on the statistical population data.The spatial and temporal characteristics of population flow in Liaoning Province are analyzed by using the population flow trend,population flow speed,population flow scale and other indicators.The results show that:(1)The population of Liaoning Province is decreasing year by year,and the population of Shenyang and Dalian is increasing slowly.According to the annual population of each city in Liaoning Province,Chaoyang City has the largest extreme difference of population,with 23.91 k people;Benxi City has the smallest extreme difference of population,with 4.67 k people.Except Shenyang and Dalian,the minimum population of other cities is in 2017,2018 and 2019,and the maximum population is in 2012 and 2013.(2)The trend of population flow is seasonal.The research time is divided into Autumn(August-October),Winter(November-January)and Spring(February-April).Fitting the monthly average population of 14 cities in Liaoning Province in the eight years(2012 – 2019),the monthly population change curve analysis is obtained.(3)The urban population inflow trend of the high level is large,while the urban population outflow situation of the low level is large.The population flow rate of prefecture-level cities is 2,300-6,900 people / month.In the eight years,the monthly population flow scale indexes are negative,among which the monthly population flow scale index of Fushun City is-0.47%,and the monthly population flow scale index of Dalian City is-0.05%.It can be seen from the analysis of population flow trend and population flow speed that,the sub provincial cities are ahead of other prefecture-level cities in terms of population flow and population flow expansion increment.(4)The population flow into the central area and the loss central area gradually revealed.Through the analysis of population spatial concentration degree,it is found that the population inflow center of Liaoning province is concentrated in Shenyang and Dalian Cities,especially Dalian City;In addition to the two sub provincial cities(Shenyang and Dalian Cities),the population inflow scale of Eastern Liaoning is also high;In the eight years,the center of population loss has spread from inside to outside,and then gradually turned to the west of Liaoning Province,and the north of Liaoning Province has a trend of backflow.