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Analysis on characteristics of temporal-spatial potential evapotranspiration distribution in Gansu based on cloud mode.
- Source :
- Transactions of the Chinese Society of Agricultural Engineering; Apr2015, Vol. 31 Issue 8, p152-158, 7p
- Publication Year :
- 2015
-
Abstract
- Characteristics of temporal-spatial potential evapotranspiration (ET<subscript>0</subscript>) distribution in Gansu Province were studied based on the Cloud model, which is a mathematical representation of qualitative concepts including expected value Ex, entropy En and hyper entropy He, integrates the fuzziness and randomness of qualitative concept in a unified way, and is a new method for the transformation between the qualitative and the quantitative. The values of ET<subscript>0</subscript> were calculated by Penman-Monteith. The changes of ET<subscript>0</subscript> in time were analyzed at monthly, seasonal and yearly intervals, respectively, and spatial changes were mainly divided into 4 parts: Hexi area, the middle, east and south area of Gansu. All data of 63 years (1951-2013) were collected at 29 meteorological stations involving the above districts in Gansu. All ET<subscript>0</subscript> data were achieved by the soft Interactive data language. The indices of homogeneity and stability were used for reflecting characteristics of temporal-spatial distribution of ET<subscript>0</subscript>, which were achieved by Cloud mode, solving the uncertain conversion of qualitative concept and quantitative description. And the changes of ET<subscript>0</subscript> in time (monthly, seaonal and annual) and space were analyzed by the linear change and the contour image. The results showed annual variation in ET<subscript>0</subscript> had a fluctuation and increasing tendency, and the tendency rate was 2.11 mm/(10a) in all study area (P<0.05). The monthly change curve of ET<subscript>0</subscript> for 63 years was single apex type, which was: ET<subscript>0</subscript> in June and July was higher than that in other months. In homogeneity and stability aspects of ET<subscript>0</subscript>, from November to March of the next year was better than from April to August in the same year. At the same time, there was significant difference on the distribution of ET<subscript>0</subscript> among seasons, and the maximum was summer, followed by spring, and the least was autumn and winter. The further analysis found that both homogeneity and stability of temporal-spatial distribution of ET<subscript>0</subscript> had no consistency among seasons. The homogeneity of ET<subscript>0</subscript> in autumn and winter was higher than that in spring and summer, but the stability in summer and autumn was better than that in spring and winter. Seen from the difference characteristics of the space, ET<subscript>0</subscript> in the northwest area of Gansu Province were larger than that in the southeast, however, the annual changes of ET<subscript>0</subscript> among areas were different for 63 years. Concretely speaking, the value of annual ET<subscript>0</subscript> in Hexi area was keeping the highest from 1951 to 2013. Seeing the changes of ET<subscript>0</subscript> in the space using the homogeneity and stability, we found ET<subscript>0</subscript> of Hexi area was most discrete and instable, the east area of Gansu had the best homogeneity and stability, and the middle and south were between them. The homogeneity and stability of ET<subscript>0</subscript> in the space was worse than that in the time. Generally, the homogeneity of the distribution of ET<subscript>0</subscript> was increasing since 1981, namely, the homogeneity from 1981 to 2013 was better than that from 1951 to 1981, and at the same time, the stability was also increasing for 63 years. [ABSTRACT FROM AUTHOR]
Details
- Language :
- Chinese
- ISSN :
- 10026819
- Volume :
- 31
- Issue :
- 8
- Database :
- Complementary Index
- Journal :
- Transactions of the Chinese Society of Agricultural Engineering
- Publication Type :
- Academic Journal
- Accession number :
- 103060320