## Data: Merged MODIS & AMSR2 sea-ice concentration at 1 km resolution. They are available as geotiffs, netcdfs, pngs and pdfs (discontinued on December 5th, 2019) in the respective directories. A detailed description is given under "Directory structure".

## Changelog:
	- 2020/02/19 (vl): Geolocation information was added to all netCDF files retrospectively, so that they can now be loaded into GIS programs like SNAP or QGIS and are immediately in the right projection.
	- 2022/03/21 (vl): Data now available for time since 20171001 (October through May). All netCDF files now include ther merged, MODIS and AMSR2 SIC as well as uncertainty estimates for the merged SIC. Reference updated to Ludwig et al., 2020

## Interactive browsing: https://seaice.uni-bremen.de/databrowser/#p=MODIS-AMSR2

## Reference: Ludwig, V., Spreen, G. and Pedersen, L. T.: Evaluation of a New Merged Sea-Ice Concentration Dataset at 1 km Resolution from Thermal Infrared and Passive Microwave Satellite Data in the Arctic. Remote Sens. 2020, 12, 3183, doi.org/10.3390/rs12193183

## Contact: Valentin Ludwig (vludwig@uni-bremen.de), Gunnar Spreen(gunnar.spreen@uni-bremen.de)

## Acknowledgement: If you use this dataset or the images in a presentation or publication, please refer to Ludwig et al. (2019) in the text. The reference is given above. Also, please put the following or an equivalent statement into the Acknowledgements: "We thank the Institute of Environmental Physics, University of Bremen for the provision of the merged MODIS&AMSR2 sea-ice concentration dataset at https://seaice.uni-bremen.de/data/modis_amsr2 (last access [date_of_last_access]).". Thanks!

## Coordinates are given in the file coordinates_npstere_1km_arctic.nc in the folder "netcdf"

## Filename structure: *quantity*_*sensor1*-*platform1*_*sensor2*-*platform2*_*merged*_*hemisphere*_*resolution*_*date*.*filetype*. *quantity* is sea-ice concentration (sic), *sensor1* is MODIS, *platform1* is Aqua, *sensor2* is AMSR2, *platform2* is GCOM-W1, *merged* means a merged dataset,*hemisphere* is north (nh = northern hemisphere), *resolution* is 1000m, *date* is the acquisition date as YYYYMMDD, *filetype* is the respective filetype (.tif, .nc, .png or .pdf). This results in sic_modis-aqua_amsr2-gcom-w1_merged_nh_1000m_20190826.tif. Polarstern data have the suffix *_Polarstern_19-08-28_00-00.tif*, where 19-08-28_00-00 is the date and time of the RV Polarstern as YY-MM-DD_hh-mm.

## Directory structure: The directory structure is *filetype*/*region*/*period*. The following data are available:
	- geotiff:
		- Arctic:
			- 2019: Arctic-wide (north of 60°) sea-ice concentration data as geotiffs, starting on 2019/08/26 and updated operationally
		- MOSAiC_StartRegion:
			- 2019: geotiffs of the envisioned start region for the MOSAiC expedition from 2019/08/27 through 2019/10/27	
		- Polarstern:
			- operational: geotiff of the 800 km by 800 km around the current position of RV Polarstern, starting on 2019/08/27 and updated operationally. The end of the filename ('Polarstern_*yy*_*mm*_*dd*_*HH*_*MM*') gives the date and time of the RV Polarstern position.
	- netcdf:
		- Arctic:
			- 2019: Arctic-wide (north of 60°) sea-ice concentration data as netcdfs, starting on 2019/08/26 and updated operationally
			- current: Only the latest pdf of the current position of RV Polarstern.
	- png:
		- Arctic:
			- 2019: Arctic-wide (north of 60°) sea-ice concentration data as png images, starting on 2019/08/29 and updated operationally. They are offered in two colormaps: A blue-to-white one which is more intuitive (filename '...visual.png') and a false-color one which provides more details (filename '...nic.png')
			- current: Only the latest png of the Arctic-wide sea-ice concentration
		- MOSAiC_StartRegion:
			- 2019: pngs of the envisioned start region for the MOSAiC expedition, from 2019/08/27 through 2019/10/27.
			- current: Only the latest png of the envisioned start region for the MOSAiC expedition.
		- Polarstern:
			- operational: png of the 800 km by 800 km around the current position of RV Polarstern, starting on 2019/08/27 and updated operationally. The end of the filename ('Polarstern_*yy*_*mm*_*dd*_*HH*_*MM*') gives the date and time of the RV Polarstern position.They are offered in two colormaps: A blue-to-white one which is more intuitive (filename '...visual.png') and a false-color one which provides more details (filename '...nic.png'). The file without colormap specification uses the nic colormap. The files without timestring are symbolic links to the respective files with timestring.
			- current: Only the latest png of the current position of RV Polarstern using the nic colormap.

	- pdf:
		### PLEASE NOTE: The operational producing of pdf files has been discontinued starting December 5th, 2019. They can still be produced upon request . The request can be directed to vludwig(at)uni-bremen.de. ###
		- Arctic:
			- 2019: Arctic-wide (north of 60°) sea-ice concentration data as pdf images, starting on 2019/08/29 and updated operationally. They are offered in two colormaps: A blue-to-white one which is more intuitive (filename '...visual.pdf') and a false-color one which provides more details (filename '...nic.pdf')
		- MOSAiC_StartRegion:
			- 2019: pdfs of the envisioned start region for the MOSAiC expedition, from 2019/08/29 through 2019/10/27
			- current: Only the latest pdf of the envisioned start region for the MOSAiC expedition.
		- Polarstern:
			- operational: pdf of the 800 km by 800 km around the current position of RV Polarstern, starting on 2019/08/26 and updated operationally. The end of the filename ('Polarstern_*yy*_*mm*_*dd*_*HH*_*MM*') gives the date and time of the RV Polarstern position. The file without colormap specification uses the nic colormap. The files without timestring are symbolic links to the respective files with timestring.
			- current: Only the latest pdf of the current position of RV Polarstern using the nic colormap.