Human Activities Enhance Radiation Forcing through Surface Albedo Associated with Vegetation in Beijing

Abstract

The impact of human activities on vegetation has been the focus of much research, but the impact on radiation energy through surface albedo associated with vegetation greenness and length of the growth season is still not well documented. Based on the land cover data for the years 2000 and 2015, this study first divided the land cover change in Beijing from 2000 to 2015 into five types according to the impact of human activities and vegetation resilience, namely, old urban areas (OU), urban expansion areas (UE), cropland (CP), mixed pixel areas (MP, which means the land covers other than urban expansion which had changed from 2000 to 2015), and the residual vegetation cover areas (pure pixels (PP), dominated by natural and seminatural vegetation, such as grassland, forest, and wetland). Then, we calculated the direct radiative forcing from the albedo change from 2000 to 2015 and analyzed the effect of vegetation on the albedo under different land cover types based on multi-resource Moderate Resolution Imaging Spectroradiometer (MODIS) products of vegetation, albedo, and solar radiation. The results showed that the most typical changes in land cover were from urban expansion. By comparing the PP with the four human-affected land cover types (OU, UE, MP, and CP), we confirmed that the radiative forcing increment between 2001–2003 and 2013–2015 in PP (0.01 W/m2) was much smaller than that in the four human-affected land cover types (the mean increment was 0.92 W/m2). This study highlights that human activities affected vegetation growth. This, in turn, brought changes in the albedo, thereby enhancing radiative forcing in Beijing during 2000–2015.

Exploring on the Eco-Climatic Effects of Land Use Changes in the Influence Area of the Yellow River Basin from 2000 to 2015

“…Because of the different vegetation growth conditions among different land use types, the differences between land use types are reflected in biophysical parameters such as albedo, resulting in different energy balance effects [10]. When exploring the climate effects of land use change from the perspective of radiation force, it is important to consider not only the radiation force corresponding to albedo, but also the radiation force corresponding to the ground and atmosphere [19], because the radiation force considering albedo only includes shortwave radiation, which has a limited influence on the overall energy balance and the parameter changes in the mechanism for regulating local energy [10]. The results of the study show that the shortwave pattern of change is not obvious in the five land-use types, but the increasing intensity of human activity, after the superimposition of long-wave radiation, shows a clear pattern of change of R n for each land-use type.…”

“…Furthermore, LUCC can influence climate locally, regionally, and globally by altering biogeophysical processes (such as surface albedo and evapotranspiration) and biogeochemical processes (such as carbon cycling and greenhouse gas emissions) [11][12][13][14][15], exploring the effect of LUCC is helpful to understand the biogeophysical and biogeophysical mechanism of the surface energy balance, urban heat island, and climate systems. In addition, the LST, which is considered as a key variable in many applications, including agriculture, hydrology, and meteorology, and it is an important parameter in the study of surface energy balance and water cycle processes [16][17][18][19].…”

Influence of Land Use Change on the Surface Albedo and Climate Change in the Qinling-Daba Mountains

“…The processed surface albedo data and solar radiative data were integrated using a formula proposed by Tang et al [38] to calculate the atmospheric top radiative forcing (RFTOA) over the Qinling-Daba mountains during the period of 2000-2015.…”

Spatial Heterogeneity of Plant Diversity within and between Neighborhoods and Its Implications for a Plant Diversity Survey in Urban Areas

“…The number of patches surveyed per neighborhood ranged from five to 13 (Figure 1 and Appendix A Figure A1). All patches surveyed are artificial green spaces [35], and there is no natural or semi-natural vegetation. The patches surveyed in each neighborhood were spatially balanced and they covered more than 55% of the green patches with sizes larger than 400 m 2 (except in Jiayuanerli, which contained an excessive number of patches).…”