Spatial Variation of Surface Energy Fluxes Due to Land Use Changes across China

Enjun Ma,Qian Zhang,Anping Liu,Xiangzheng Deng

doi:10.3390/en7042194

Abstract

We estimate the heat flux changes caused by the projected land transformation over the next 40 years across China to improve the understanding of the impacts of land dynamics on regional climate. We use the Weather Research and Forecasting (WRF) model to investigate these impacts in four representative land transformation zones, where reclamation, overgrazing, afforestation, and urbanization dominates the land use and land cover changes in each zone respectively. As indicated by the significant variance of albedo due to different land use and cover changes, different surface properties cause great spatial variance of the surface flux. From the simulation results, latent heat flux increases by 2 and 21 W/m2 in the reclamation and afforestation regions respectively. On the contrary, overgrazing and urban expansion results in decrease of latent heat flux by 5 and 36 W/m2 correspondingly. Urban expansion leads to an average increase of 40 W/m2 of sensible heat flux in the future 40 years, while reclamation, afforestation, as well as overgrazing result in the decrease of sensible heat flux. Results also show that reclamation and overgrazing lead to net radiation decrease by approximately 4 and 7 W/m2 respectively, however, afforestation and urbanization lead to net radiation increase by 6 and 3 W/m2 respectively. The simulated impacts of projected HLCCs on surface energy fluxes will inform sustainable land management and climate change mitigation.

Highlights

Land use/cover change (LUCC) affects climate system at local, regional and global scales through various biogeochemical and biogeophysical processes [1,2,3]
Most of these studies only focused on the effects of human-induced land cover changes (HLCCs) on temperature and precipitation [18,19,20,21]; little is known about the effects on surface energy fluxes so far, such as latent heat flux and sensible heat flux
The future spatial variation of surface energy fluxes due to land use changes can be simulated based on different underlying surface data, and the impacts of land use changes on the climate can be quantified through the difference of the two simulation results between the baseline test and sensibility test as follows: Ei=Pi − Bi where E refers to the effects of future land use change on the surface energy fluxes; i indexes the annual or monthly average surface energy fluxes; and P and B denotes to the simulation results obtained with the Weather Research and Forecasting (WRF)-ARW model based on underlying surface in 2010 and 2050 respectively in this study

Summary

Introduction

Land use/cover change (LUCC) affects climate system at local, regional and global scales through various biogeochemical and biogeophysical processes [1,2,3]. The interaction between land surface and atmosphere mainly works through the exchanges of momentum, energy and water, among which the exchange of energy plays a key role in affecting climate system In this context, it is of great importance to investigate the effects of LUCC on surface energy fluxes. There have been many studies that attempted to reveal the impacts of human-induced land cover changes (HLCCs) on the regional climate in China [3,14,16,17] Most of these studies only focused on the effects of HLCCs on temperature and precipitation [18,19,20,21]; little is known about the effects on surface energy fluxes so far, such as latent heat flux and sensible heat flux. Previous studies on China just concentrated on one typical case study areas, for example, Northeast

Methods

Results

Conclusion