Open AccessGround‐based observations of clouds through both an automatic imager and human observation
Author(s) -
Silva Abel Antônio,
SouzaEcher Mariza Pereira
Publication year - 2016
Publication title -
meteorological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 59
eISSN - 1469-8080
pISSN - 1350-4827
DOI - 10.1002/met.1542
Subject(s) - cloud cover , sky , data set , environmental science , remote sensing , ground truth , scale (ratio) , similarity (geometry) , cloud computing , meteorology , statistics , mathematics , computer science , geography , cartography , artificial intelligence , image (mathematics) , operating system
The routine to determine the local cloud cover ( LCC ) drawn from sky images obtained using a ground‐based automatic imager is validated. Almost 3 years of daily data of LCC and cloud cover measurements by ground‐based human observation ( CC HO ) were compared for two Brazilian stations set 6 km apart. The linear fitting between daily values showed a co‐efficient of determination ( r 2 ) and a percent scattering of points ( SD %) of ≈ 0.77 and ≈ 19.4% respectively. These results are evidence for the significant similarity between the two sets of data. On the other hand, the level of difference found can be explained by the fact that (1) the data refer to independent micro‐scale observations of the sky from stations set a few kilometres apart and (2) the data were drawn from interpretations of cloud cover by an automatic imager and a human observer. The monthly average values of LCC and CC HO showed better linear fitting parameters r 2 = 0.95 and SD % = 6.3%. Average differences of ≈ −10% from LCC to CC HO were found. These average differences may reflect a systematic bias between the two processes of measuring cloud cover.