Estimating Fire Background Temperature at a Geostationary Scale—An Evaluation of Contextual Methods for AHI-8

Results show that while contextual estimation provides accurate temperatures for pixels with no contextual obscuration, significant deterioration of results occurs when even a small portion of the target pixel’s surroundings are obscured. To maintain the temperature estimation accuracy, the use of no less than 65% of a target pixel’s total contextual coverage is recommended. The study also examines the use of expanding window sizes and their effect on temperature estimation.

Results show that the accuracy of temperature estimation decreases significantly when expanding the examined window, with a 50% increase in temperature variability when using a larger window size than 5×5 pixels, whilst generally providing limited gains in the total number of temperature estimates (between 0.4%–4.4% of all pixels examined). The work also presents a number of case study regions taken from the AHI-8 disk in more depth, and examines the causes of excess temperature variation over a range of topographic and land cover conditions.

Dataset consists of three zipped files containing netCDF4 images for the selected times and locations outlined in Hally et al. 2018. The images contained in the FULLDISK files are cloudmask products for the days and times in the file names - file naming convention starts with YYYYMMDDHHmm, with the produced cloudmask corresponding to this UTC time of image capture. The files themselves consist of a masked binary array, with values of 0 assigned to pixels clear of cloud, and values of 1 applied to pixels where cloud is detected.

Masked values are either pixels external to the imaged disk, or pixels that have an ocean mask applied (see dap.nci.org.au/thredds/remoteCatalogService?command=subset&catalog=http://dapds00.nci.org.au/thredds/catalog/rr5/satellite/obs/himawari8/FLDK/ancillary/catalog.xml&dataset=rr5/satellite/obs/himawari8/FLDK/ancillary/20150127000000-P1S-ABOM_GEOM_LAND-PRJ_GEOS141_2000-HIMAWARI8-AHI.nc for further information).

EXTRADATA_SMALLFILES files are subset files of the fulldisk based upon the coordinates given from Hally et al 2018. These files consist of arrays that are 301 x 301 pixels in size - the last row and column is empty and should be discarded before further use. The timestamps are as demonstrated with the fulldisk versions, and the file folders are the only descriptor of the location given.

The netCDF4 metadata of all of the files supplied has not been changed from the ABOM dataset that the cloudmask is based upon, and as such should NOT be trusted as truthful data. References: Hally, B., Wallace, L., Reinke, K., Jones, S., Engel, C., & Skidmore, A. (2018). Estimating Fire

Background

Temperature at a Geostationary Scale—An Evaluation of Contextual Methods for AHI-8. Remote Sensing, 10(9). doi.org/10.3390/rs10091368