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MODIS Black-Sky Albedo Climatology (2013-2022)
Giulia Roccetti1, 2 , Luca Bugliaro3, Felix Gödde2, Claudia Emde3, 2, Ulrich Hamann4, Mihail Grigorov Manev2, Michael Fritz Sterzik1, and Cedric Pascal Wehrum2
1European Southern Observatory
2Ludwig-Maximilians-Universität München
3German Aerospace Center
4Federal Office of Meteorology and Climatology MeteoSwiss
First published:
July 8, 2024
DOI: 10.57970/pt52a-nhm92
Keywords:
albedo
MODIS
energy budget
radiative transfer
seasonal variability
climatology

Roccetti, G., Bugliaro, L., Gödde, F., Emde, C., Hamann, U., Manev, M., G., Sterzik, M., F., and Wehrum, C., P. (2024): MODIS Black-Sky Albedo Climatology (2013-2022). LMU Munich, Faculty of Physics. (Dataset). DOI: 10.57970/pt52a-nhm92

wget and curl are the two standard tools that are available on most Linux and macOS computers. wget contains a feature for downloading a list of files: 
wget -x -nH -i 'https://opendata.physik.lmu.de/pt52a-nhm92/?list'
curl is missing a feature like that, but the same functionality can be created by combining curl and xargs: 
curl 'https://opendata.physik.lmu.de/pt52a-nhm92/?list' | xargs -I URL -n1 bash -c 'curl --create-dirs -o ${1:31} ${1}' -- URL
Abstract
This dataset contains a climatological average of Earth's surface black-sky albedo, constructed by averaging the MODIS Surface Reflectance dataset MCD43D (version 6.1) over a period of ten years (from 2013 to 2022). In particular, we used the products MCD43D42 to MCD43D48, corresponding to seven MODIS spectral bands in the visible and the near-infrared. The dataset contains the climatological albedo maps for all seven spectral bands, as well as the origin of every pixel for each band. The dataset consists of 365 files, one for each day of the year, with a spatial resolution of 30 arc seconds in latitude and longitude. The details of the climatological average are discussed in the paper "HAMSTER: Hyperspectral Albedo Maps dataset with high Spatial and TEmporal Resolution" (Roccetti et al., 2024, https://doi.org/10.5194/egusphere-2024-167).
README.md

MODIS Black-Sky Albedo Climatology (2013-2022)

Authors: Giulia Roccetti, Luca Bugliaro, Felix Gödde, Claudia Emde, Ulrich Hamann, Mihail Manev, Michael Fritz Sterzik, Cedric Wehrum

Contact: giulia.roccetti@eso.org giuli.roccetti@gmail.com

Related publication: HAMSTER: Hyperspectral Albedo Maps dataset with high Spatial and TEmporal Resolution, Roccetti et al., 2024, https://doi.org/10.5194/egusphere-2024-167

The dataset has 365 files, each corresponding to a day of the year (DOY), containing the seven MODIS climatology spectral bands.

Spectral bands of MODIS in the VIS/NIR providing information about surface albedo.

band    wavelength [nm]
1 645
2 858
3 469
4 555
5 1240
6 1640
7 2130

For each pixel we provide the values of the black-sky albedo for the seven MODIS spectral bands, as well as a flag indicating at which step of the climatological average the pixel has been filled.

Flag values and corresponding meaning:

0 - Missing pixel

1 - 41 - Filled with the mean value between (DOY - n) and (DOY + n), if both values are present

42 - Filled with the mean over 10 days around the DOYs before and after the current DOY with filled values until local solar zenith angle of 90°

43-46 - Filled with a spatial average over a square of side length m = [3,5,7,9] pixels

47 - Filled with the mean over all longitudes and a latitude band of 2° around the actual latitude

48 - Filled with the mean over all DOYs for that pixels

49 - Ocean

Description of the variables in the netCDF4 files:

variable name                  dimension      resolution                      
Latitude (lat) 21600 30 arcsec
Longitude (lon) 43200 30 arcsec
Albedo_BSA_Band1      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band1      lat, lon 30 arcsec x 30 arcsec
Albedo_BSA_Band2      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band2      lat, lon 30 arcsec x 30 arcsec
Albedo_BSA_Band3      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band3      lat, lon 30 arcsec x 30 arcsec
Albedo_BSA_Band4      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band4      lat, lon 30 arcsec x 30 arcsec
Albedo_BSA_Band5      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band5      lat, lon 30 arcsec x 30 arcsec
Albedo_BSA_Band6      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band6      lat, lon 30 arcsec x 30 arcsec
Albedo_BSA_Band7      lat, lon 30 arcsec x 30 arcsec
Albedo_Origin_Band7      lat, lon 30 arcsec x 30 arcsec

Temporal evolution of Earth's albedo for MODIS band 1.

Download_movie

Example to read and plot the data with python and netCDF4:

import netCDF4 as nc
import matplotlib.pyplot as plt 
data = nc.Dataset("DOY001.nc","r",format='NETCDF4')
albedo = data.variables["Albedo_BSA_Band2"]
fig, axs = plt.subplots(1,2,figsize=(20,8))
im = axs[0].imshow(albedo[7500:12500,10500:15000], vmin=0, vmax=0.4)
fig.colorbar(im, ax=axs[0])
im = axs[1].imshow(albedo[10650:11050,10550:10900], vmin=0, vmax=0.4)
fig.colorbar(im, ax=axs[1])
Black-sky albedo band 2 (858 nm) of Central America and the Caribbean and zoom-in on the Galapagos Islands
Black-sky albedo band 2 (858 nm) of Central America and the Caribbean and zoom-in on the Galapagos Islands

Acknowledgements

We acknowledge NASA LAADS DAAC for providing the MCD43D42-48 data products.

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