In the deeper part of polar ice sheets, air hydrates are the primary air inclusions. They trap most of the ancient air molecules used for paleoclimatic reconstructions in their crystal structure. Furthermore, their number and size was found to correlate with past climate. This dataset presents the raw data of air hydrate parameters of the EPICA Dronning Maud Land (EDML) ice core from 1255 m to 2771 m depth. Air hydrate parameters were measured and analyzed in 74 ice thick section microphotographs using digital image analysis. The images were analyzed by Florian Painer at the Alfred Wegener Institute, Bremerhaven and the analysis routines were implemented in Python using open-source libraries. The aim was to develop a semi-automated analysis routine and to provide a high-resolution record of air hydrate properties of the EDML ice core. In total, about 183.000 air hydrates were segmented from the microphotographs and analyzed using digital image analysis. The microphotographs were obtained in the years 2002 - 2006 during the Antarctic field season, shortly after the sample was drilled, using an optical microscope (Kipfstuhl et al., 2006; Kipfstuhl, 2007).

The individual files contain the following variables:- Region label: A region consists of connected pixels. For instance, a segmented air hydrate.- Area: Number of pixels of the region.- Diameter of area-equivalent circle: Diameter of a circle with the same area as the region.- Perimeter: According to scikit-image (0.24.0) conventions.- 0-coordinate of centroid: Coordinate according to scikit-image (0.24.0) conventions. Corresponds to "Y" in a Cartesian coordinate system with the origin in the top left corner of the image.- 1-coordinate of centroid: Coordinate according to scikit-image (0.24.0) conventions. Corresponds to "X" in a Cartesian coordinate system with the origin in the top left corner of the image.- Minor axis: Of a fitted ellipse according to scikit-image (0.24.0) conventions.- Major axis: Of a fitted ellipse according to scikit-image (0.24.0) conventions.- Eccentricity: Of a fitted ellipse according to scikit-image (0.24.0) conventions.- Orientation: Of the major axis of a fitted ellipse according to scikit-image (0.24.0) conventions. Convert to "real angle" in degrees using: real angle = orientation * (180/pi) + 90- Mean gray value: Mean gray value of the region.- Circularity: Circularity = (4piArea) / (Perimeter**2). A value of 1 would equal a perfect circle.