Using more than three million Landsat satellite images, this research developed the first global impervious surface area (GISA) dataset from 1972 to 2019. Based on 120,777 independent and random reference sites from 270 cities all over the world, the omission error, commission error, and F-score of GISA are 5.16%, 0.82%, and 0.954, respectively. Compared to the existing global datasets, the merits of GISA include: (1) It provided the global ISA maps before the year of 1985, and showed the longest time span (1972–2019) and the highest accuracy (in terms of a large number of randomly selected and third-party validation sample sets); (2) it presented a new global ISA mapping method including a semi-automatic global sample collection, a locally adaptive classification strategy, and a spatio-temporal post-processing procedure; and (3) it extracted ISA from the whole global land area (not from an urban mask) and hence reduced the underestimation. Moreover, on the basis of GISA, the long time series global urban expansion pattern (GUEP) has been calculated for the first time, and the pattern of continents and representative countries were analyzed. The two new datasets (GISA and GUEP) produced in this study can contribute to further understanding on the human’s utilization and reformation to nature during the past half century, and can be freely download from http://irsip.whu.edu.cn/resources/dataweb.php.
This paper gives a complete commentary on some popular gradings which based on the 2×2 contingency table, for one—dimensional seismologic prediction. It contains:
In view of the statistical correlation, the Wallen gradingV=√QS is the most equitable one amomg all gradings.
Each one of the three gradings: Zhenchao Gu gradingS, Obuhov gradingQ and Shaoxie Xu gradingR, has its own inadequacy although they are so easy for use.
A set of gradings can be derived fromV. The harmonic mean ofS andQ, H(S,Q) and the Hedike gradingSH are the members of this set. The order of some popular gradings are given in Theorem 5. 3.
In view of the measure of the overlapping part a gradingW is introduced. Another set of gradings may be derived from it. The index of efficiencyh is the severest one among this set.
