Spatial and temporal characteristics of droughts in the Northeast China Transect

Abstract

In this study, drought trends and change magnitudes of the Northeast China Transect (NECT) were analyzed using the Mann-Kendall test and Theil-Sen's slope estimator. Meteorological data from 20 meteorological stations of NECT region from 1957 to 2012 were used. Results demonstrated that five stations had significant negative trends in precipitation. The magnitudes of the significant negative trends at the 95 % confidence level varied from -2.41 ± 1.05 mm year -1 at Tonghe station to -1.11 ± 0.51 mm year -1 at Qianguoerluosi station. Analysis of the seasonal precipitation series showed a mix of negative and positive trends. Many stations also exhibited strong contrasting seasonal trends that counterbalanced one other at the yearly level. In addition, cluster analysis based on discrete wavelet transform (DWT) was applied to the standard precipitation index (SPI) series. Results revealed three different and spatially well-defined subregions (east, center and west regions of NECT). Due to the decrease in precipitation from the east to the west, land use varies from forest regions in the east, to agriculture in the center, to pastoral areas in the west. Characteristics of drought events for each representative station of different subregions are explored using temporal evolution of the SPI values. Results showed that severe or extreme droughts occurred in 2001, 2003 in Tonghe, 1980 in Tongliao and 2005 123Nat Hazards (2015) 76:601-614 DOI 10.1007/s11069-014-1507 has great potential for examining spatial coherence of regional drought, which was consistent with not only the precipitation spatial distribution but also the characteristics of land use in the study area. This study not only provides important information on drought variability in the NECT, but also provides useful information for improving water management strategies and planning agricultural practices.

Decomposition of Limestone in Hot Metal at 1300 °C

“…Using limestone instead of lime can reduce carbon dioxide emissions, improve converter gas quantity and gas calorific value, reduce production cost, meet the requirement of converter tapping temperature and composition, and thus lead to great economic benefits. The present authors [3,4,5] established the static model for converter steelmaking by using limestone instead of lime, and proved the theoretical feasibility of limestone instead of lime. Furthermore, physical simulation of converter steelmaking had been conducted and the optimum parameters had been obtained in the condition of top lance powder injection and bottom powder injection under the laboratory conditions.…”

“…[24] Because the radius of bivalent iron ions is smaller than the other ions in early slag, ferrous oxide diffuses fast when early slag permeates along the lime hairline cracks and pores and quickly dissolves in lattice of calcium oxide, generating calcium oxide solid solution with lower ferrous oxide and lower calcium oxide solution with higher ferrous oxide. Carbon dioxide from limestone calcination can react with the elements in hot metals such as C, Si, Mn, and Fe, [3,5] so there is some ferrous oxide produced in this experiment. Then the ferrous oxide permeates into lump lime, and this is why some Fe can be seen by using line analysis and map analysis.…”

“…The decomposition of calcium carbonate is strong endothermic reactions as shown in Equation 1and 2. [3,5] CaCO 3 ¼ CaOðsÞ þ CO 2 ðgÞ ð 1Þ…”

“…In addition, the CO 2 generated from limestone decomposition may take part in and also promote kinetically the slagging and the steelmaking reactions such as decarburization and dephosphorization, and thereby to reduce oxygen consumption. Under such a background, some researchers [3][4][5][6][7][8][9][10][11][12] proposed to use limestone instead of lime for the slagging process in converter steelmaking. With this method, the problems such as the lime activity decreasing with moisture absorption and the lime loss in transportation, loading, and unloading can be solved.…”

Seasonal tropospheric cooling in Northeast China associated with cropland expansion

“…Northeast China has suffered crippling growing season droughts recently, creating widespread agricultural impacts (Yi 2014). These droughts are recent manifestations of a much longer four-decade decrease in summer and autumn rainfall in the region (Piao et al 2010, Ye 2014, Wang et al 2015. In 2014, for example, a drought in Liaoning Province in Northeast China affected 1.8 million hectares of cropland (Yi 2014), leading to an 1.5% drop in country-wide corn production (Larson 2014).…”