Cloud Coverage

For the CC data from the layers used, MODIS (Moderate Resolution Imagin Spectroradiometer) instrument data sets which are 36 bands multispectral imaging device on Terra and Aqua polar orbital twin satellites were used. The data is available in this website. The data set used is MOD35_L2 (6.1.) And MYD35_L2 (6.1.), which includes the "Cloud Mask" layer, covers the years 2000-2019 for Terra and 2003-2019 for Aqua. The spatial resolution of the data used is 1km x 1km per pixel. The served data in Hdf4 format was converted to GEOTIFF format and according to WGS84 datum criteria, 288 hdf files presented daily were combined and a single image was obtained. The obtained daily images were averaged and a one mean cloudiness image was created in GEOTIFF format. In this process, only night and twilight data were used as it was an astronomical observation criteria. The downloaded data was converted to daily GEOTIFF formats and time-consumed only at night and twilight data. The size of the data used is approximately 48 TB. This study has been analyzed with the most comprehensive and spatial resolution database ever used for global cloudiness research. Using data from both satellites for analysis makes temporal resolution even more precious.

This global image was mapped by adding compass, scale, legends etc. with the help of GIS software. In this map where global cloudiness is given; cloudiness increases in medium latitudes according to many parameters such as temperature, wind speed, wind direction and orography. The changes in the global cloudiness in the Hadley cells, the rotation of the earth and the wind direction, may also explain the dense cloudiness in these latitudes. In addition, the average cloudiness decreases, even at the poles, to a minimum.