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The relationship between satellite-derived low cloud frequency and the occurrence of tropical montane cloud forest (TMCF) in Taiwan was investigated. From daily MODIS cloud mask products between 2003 and 2012 the low cloud class was extracted and mean low cloud frequency was calculated for Taiwan. This low cloud frequency map was blended with an existing plot-based vegetation classification for Taiwan to analyze the relationship between low cloud frequency and TMCF occurrence. Receiver operating characteristics curves and the area under the ROC curve (AUC) were used to analyze if a relationship exists. No relationship was found for all four TMCF types taken together (AUC = 0.61) and for the dominant TMCF type, Quercus montane evergreen broad-leaved cloud forest (AUC = 0.5). Strong relationships were found for the two spatially-restricted TMCF types, Fagus montane deciduous broad-leaved cloud forest (AUC = 0.91) and Pasania-Elaeocarpus montane evergreen broad-leaved forest (AUC = 0.84), as well as for the second dominant type Chamaecyparis montane mixed cloud forest (AUC = 0.74). The results show that low cloud frequency thresholds might be associated with specific cloud forest types in Taiwan. Further studies should incorporate information about cloud base height, cloud density, and cloud immersion time as well as satellite-based cloud frequency information with a higher temporal resolution. Combination with satellite-based land cover classifications for Taiwan would allow quasi-continuous observation of TMCF changes. Such knowledge would be the precondition for effective protective actions concerning this exceptional but threatened ecosystem.

http://dx.doi.org/10.3390/rs71012986

Masks of ground fog in the taiwanese mountains (2002 - 2014) processed based on data of all MODIS overflights using the algorithm DOGMA (Schulz, M.; Thies, B.; Chang, S. & Bendix, J. (2016): Detection of ground fog in mountainous areas from MODIS (Collection 051) daytime data using a statistical approach. Atmospheric Measurement Techniques 9, 1135 - 1152 DOI: http://dx.doi.org/10.5194/amt-9-1135-2016.)

Ground fog masks were created from MODIS data from 2003 to 2014 using the method DOGMA. From those masks the ground fog frequency was calculated for each month separately.

This dataset contains fog frequencies for Europe averaged over all 30 GWSs (general weather situations) after Hess & Brezowsky. Time period covered: 2006-01-01 to 2015-12-31

A description of the data can be found in this paper:
Egli, S., Thies, B., & Bendix, J. (2019). A spatially explicit and temporally highly resolved analysis of variations in fog occurrence over Europe. Quarterly Journal of the Royal Meteorological Society, 1–20. https://doi.org/10.1002/qj.3522

The original fog masks are based on Meteosat Second Generation data that were processed based on the algorithm described in Egli, S., Thies, B. & Bendix, J. (2018). A Hybrid Approach for Fog Retrieval Based on a Combination of Satellite and Ground Truth Data. Remote Sensing. 2018.