Influence of snow cover changes on surface radiation and heat balance based on the WRF model

Abstract

The snow cover extent in mid-high latitude areas of the Northern Hemisphere has significantly declined corresponding to the global warming, especially since the 1970s. Snow-climate feedbacks play a critical role in regulating the global radiation balance and influencing surface heat flux exchange. However, the degree to which snow cover changes affect the radiation budget and energy balance on a regional scale and the difference between snow-climate and land use/ cover change (LUCC)-climate feedbacks have been rarely studied. In this paper, we selected Heilongjiang Basin, where the snow cover has changed obviously, as our study area and used the WRF model to simulate the influences of snow cover changes on the surface radiation budget and heat balance. In the scenario simulation, the localized surface parameter data improved the accuracy by 10 % compared with the control group. The spatial and temporal analysis of the surface variables showed that the net surface radiation, sensible heat flux, Bowen ratio, temperature and percentage of snow cover were negatively correlated and that the ground heat flux and latent heat flux were positively correlated with the percentage of snow cover. The spatial analysis also showed that a significant relationship existed between the surface variables and land cover types, which was not obviously as that for snow cover changes. Finally, six typical study areas were selected to quantitatively analyse the influence of land cover types beneath the snow cover on heat absorption and transfer, which showed that when the land was snow covered, the conversion of forest to farmland can dramatically influence the net radiation and other surface variables, whereas the snow-free land showed significantly reduced influence. Furthermore, compared with typical land cover changes, e.g., the conversion of forest into farmland, the influence of snow cover changes on net radiation and sensible heat flux were 60 % higher than that of land cover changes, indicating the importance of snow cover changes in the surface-atmospheric feedback system.

Diurnal cycle of surface energy fluxes in high mountain terrain: High‐resolution fully coupled atmosphere‐hydrology modelling and impact of lateral flow

“…Figure 13 presents the spatial pattern of the mean diurnal peak value and peak time of surface energy fluxes from June to September in 2008 for the headwater and its surrounding area. Comparing Figure 13 to Figure 1b, the peak value of Rn in high mountain peaks is relatively lower than it in the valley and the flat area, because of increased snow cover at higher elevation (Minder et al, 2016; Yu et al, 2017). The diurnal peak time of Rn shows slight spatial variations according to the terrain height, close to local noontime.…”

Seasonal Local Temperature Responses to Paddy Field Expansion from Rain-Fed Farmland in the Cold and Humid Sanjiang Plain of China

“…The regional statistic results showed that both rain-fed farmland and paddy fields had a similar change tendency for albedo and ET during the growing season. Generally, the albedo of water was lower than that of other land use types [59], and as a result, the albedo of paddy fields was much lower than that of rain-fed farmland in May and June when the paddy fields were filled with water. Significant albedo differences were detected in May and June (spring), −0.035 ± 0.031 and −0.028 ± 0.027, respectively.…”

Land Surface Temperature Response to Irrigated Paddy Field Expansion: a Case Study of Semi-arid Western Jilin Province, China

“…LUC-induced changes of surface biogeophysical characteristics, such as albedo 14 , surface roughness 15 , and Bowen ratios 16,17 , have direct impacts on the heterogeneity and quantity of local temperature, humidity and wind speed, which make biogeophysical processes critical to the local climate system 4,18 . At present, worldwide land cover changes have received extensive attention due to their significant effects on large-scale climate, including changes in deforestation and afforestation 19–22 , desertification 23 , and snow and ice cover 24 . Meanwhile, meso-micro-scale climate changes resulting from typical LUC are similarly notable and may even be stronger than background climate change 10,25–27 .…”