Shedding Light Upon The Dark Continent

Estimating population, GDP, and CO2 emissions of African countries using DMSP night light data

Benjamin IgnacDigital Image ProcessingDr. Kirsten de BeursUniversity of Oklahoma

The distribution, presence, and

absence of night light in Africa can tell us a story about social and

environmental phenomena

Correlation between night light and POPULATION

TEMPORAL change of night light in

Africa

Correlation between night light and GDP

Correlation between night light and CO2

EMISSIONS

DMSP offers free Stable Light data on an annual basis from

1992 to 2013Satellites: Defense Meteorological Satellite Program (DMSP)

Sensor: Operational Linescan System (OLS)

Swath: 3000km

Spatial resolution: 2.8km (smoothed)

Temporal resolution: sunsynchronous – between 20:30 and 21:30 each night

Spectral resolution: two broadband sensors, one in the visible/near-infrared (VNIR, 0.4 – 1.1μm) and thermal infrared (10.5 – 12.6μm)

Composite: 30 arc second grids, spanning -180 to 180 degrees longitude and -65 to 75 degrees latitude

DN: Frequency of light detected per pixel (0-63)

Subset: 10,000x10,000 pixels (Africa)

CompositesF101992F101993F101994F121995F121996F121997F121998F121999F142000F142001F142002F142003F152004F152005F152006F152007F162008F162009F182010F182011F182012F182013

Ancillary data

World Bank: Population and GDP midyear estimates by country (1981-2015)European Commission: CO2 time series by country (1970-2014)

http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html

http://data.worldbank.org/indicator/SP.POP.TOTL http://data.worldbank.org/indicator/NY.GDP.MKTP.CD http://edgar.jrc.ec.europa.eu/overview.php?v=CO2ts1990-2014&sort=des9

F18 2013 Nighttime Lights Composite

Methods

1. Download DMSP data2. Create GIF using TIFFs from all 21 years of data (1992-2013)3. Create Africa subsets in ENVI for 1992 and 20134. Open subsets ArcGIS

Spatial Analyst>Zonal>Zonal Statistics As Table5. Join zonal statistics to African country shape file6. Attribute GDP, population and CO2 data7. Create maps and scatterplots, calculate correlations

Compared to other continents Africa is less lit at night and has been developing slower over time

+92% total night lights

+33% per capita

Negative change in lights per capita (2013-1992):

NigeriaCentral African RepublicLibyaGabonZimbabwe

1000 10000 100000 1000000300

3000

30000

300000f(x) = 0.904879986968124 x^0.858701197791254R² = 0.881925667264371

Relationship between night light and GDP

Total night light (DN_SUM)

GDP

(in

mill

ion

USD

)

1000 10000 100000 100000079999.9999999999

799999.999999999

7999999.99999999

79999999.9999999f(x) = 13711.1580538128 x^0.585944330468512R² = 0.479974208791063

Relationship between night light and total population

Total night light (DN_SUM)

tota

l pop

ulati

on

1000 10000 100000 100000050

500

5000

50000

f(x) = 0.124672423579276 x^0.930187401998754R² = 0.884521991502267

Relationship between night light and CO2 emissions

Total night light (DN_SUM)

Tota

l CO

2 em

issi

ons (

Kilo

tons

)

Night-time lights in Africa are an adequate estimator for GDP and CO2 Emissions but less

accurate for population estimates due to Africa’s high rural population

Conclusions

R² = 0.48 (60% of Africa is rural)

R² = 0.8819

R² = 0.8845

+92% total night lights+33% per capita (1992-2013)

sources

Data:• http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html• http://data.worldbank.org/indicator/SP.POP.TOTL • http://data.worldbank.org/indicator/NY.GDP.MKTP.CD • http://edgar.jrc.ec.europa.eu/overview.php?v=CO2ts1990-2014&sort=des9 • https://giphy.com/gifs/l3V0lh7j34jKrshos

Literature:• Huang, Q., Yang, X., Gao, B., Yang, Y., & Zhao, Y. (2014). Application of DMSP/OLS Nighttime

Light Images: A Meta-Analysis and a Systematic Literature Review. Remote Sensing, 6(8), 6844-6866.

• Doll, C. N. (2008). CIESIN Thematic Guide to Night-time Light Remote Sensing and its Applications. CIESIN Thematic Guide. Retrieved from: http://sedac.ciesin.columbia.edu/binaries/web/sedac/thematic-guides/ciesin_nl_tg.pdf