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Climate transition at different scales complicates the dynamics of catchment water cycle. Examination of meteorological pattern shift enables us to have a deeper insight of the mechanism in hydrological extremes. Lake Hulun, the largest freshwater lake in Northern China, plays an important role in maintaining the regional ecological sustainability. The abrupt decrease of water level in the lake after 2000 has resulted in serious impacts on the lake's ecosystem. This paper presents a systematic analysis by linking meteorological dynamics with hydrological extremes based on the long-term precipitation, river discharge, and evapotranspiration (ET) data in the Lake Hulun watershed, which is a transition zone from desert to wetland and to permafrost along the Mongolia–China borderline. The results indicate that signals of large-scale precipitation variations can be well identified by using the Empirical Orthogonal Function (EOF). Spatially, the precipitation in the Lake Hulun watershed is dominated by two leading EOF patterns at the basin scale. The two leading patterns present complementary features of the high value centers in space. The amplitudes evolution of the leading patterns of EOF reveal that the redistribution of precipitation that occurred more in the middle flat plain and less in the mountain regions of the watershed triggers a big effect on the increasing ET and weakening runoff production due to the spatial heterogeneity in hydrological processes. Such effects are echoed by the trend patterns in precipitation and ET. The mechanism of the precipitation pattern shift is also confirmed by the large scale meteorological variations in geopotential and water vapor transport. Therefore, the change in the leading patterns of precipitation and the effects in ET triggered by the pattern shift in precipitation are the major causes of decrease in watershed runoff and the hydrological extremes in the terminal lake. [ABSTRACT FROM AUTHOR]

Open biomass burning (OBB) is one of the major factors that influences the regional climate environment and surface vegetation landscape, and it significantly affects the regional carbon cycle process and atmospheric environment. The Amur-Heilong River Basin (ARB) is a fire-prone region in high-latitude boreal forests. In this study, we used fire radiative power (FRP) obtained from a Moderate-resolution Imaging Spectroradiometer (MODIS) to estimate OBB emissions from the ARB and established a long-term series (2003–2020) with a high spatiotemporal resolution and a daily 1 km emissions inventory. The results show that the annual average emissions of CO2, CO, CH4, NMHCs, NOx, NH3, SO2, BC, OC, PM2.5, and PM10 were estimated to be 153.57, 6.16, 0.21, 0.78, 0.28, 0.08, 0.06, 0.04, 0.39, 0.66, and 0.85 Tg/a, respectively. Taking CO2 as an example, grassland fire in the dry season (mainly in April and October) was the largest contributor (87.18 Tg/a), accounting for 56.77% of the total CO2 emissions from the ARB, followed by forest fire prone to occur in April–May (56.53 Tg/a, 36.81%) and crop fire during harvest season (9.86 Tg/a, 6.42%). Among the three countries in the ARB, Russia released the most total CO2 emissions (2227.04 Tg), much higher than those of China (338.41 Tg) and Mongolia (198.83 Tg). The major fire types were crop fires (40.73%) on the Chinese side and grass fires on the Russian (56.67%) and Mongolian (97.56%) sides. Over the past decade, OBB CO2 emissions have trended downward (−0.79 Tg/a) but crop burning has increased significantly (+0.81 Tg/a). Up to 83.7% of crop fires occurred in China (2010–2020), with a concentrated and southward trend. Comparisons with the Global Fire Emission Dataset (GFED4.1s), the Fire INventory from NCAR (FINNv2.2), and the Global Fire Assimilation System (GFASv1.2) showed that our newly established emission inventory was in good agreement with these three datasets in the ARB. However, this multi-year, daily 1 km high-resolution emission inventory has the advantages of detecting more small fire emissions that were overlooked by coarse-grid datasets. The methods described here can be used as an effective means of estimating greenhouse gas and aerosol emissions from biomass combustion. [ABSTRACT FROM AUTHOR]

This article deals with the features in the morphology and dynamics of river beds and floodplains located in different natural zones and in different conditions of development of channel deformations. In preparing small-scale thematic maps (geomorphological, landscape and other maps), river valleys and their constituent river beds and floodplains are displayed in a simplified fashion using a common linear conventional sign. However, the procedure neglects the influence on the formation and development of riverbeds and floodplains from zonal processes associated with climatic features of river basins. For revealing this influence, an original small-scale map of riverbeds on a large territory of the East of the Eurasian continent covering the Asian part of Russia, Mongolia and China (Eastern transect), was compiled. The climatic zonality of both plains and highlands is widely manifested in this territory and the influence of zonality on intrazonal channel processes is emphasized. Of course, the leading factors are fluvial, but they are actively influenced by zonal natural factors. In the nival zone, they are represented by cryogenic processes, and in the semiarid zone by aeolian and halogen processes (salinization of floodplains). In the highlands, the role of horizontal zonality is less (it is manifested only in the semiarid highlands), but there the influence of azonal slope processes is intensified. Only in the humid zone, the nonfluvial factors of channel and floodplain processes are almost not manifested. The identified regularities are associated with the occurrence of dangerous emergency and extreme channel processes which differ in their specificity in each natural zone. This should be taken into account when mapping them and using river resources. [ABSTRACT FROM AUTHOR]