摘要
为减小尺度不匹配引起的冠层截留模拟偏差,文章量化了全球降雨覆盖度在子网格尺度上的时空异质性特征,并将其引入陆面过程模式Community Land Model version 5(CLM5)的冠层截留参数化方案;同时,基于全球蒸散发产品,对改进的CLM5模拟降雨截留过程的能力进行系统评估。结果表明:改进的模型显著地提升了全球植被冠层截留量模拟的合理性,模拟均值由56.66降至49.13 mm。空间上,改进模型在中低纬度湿润半湿润区(如北美、欧亚中北部)和干旱过渡带(如萨赫勒、中亚)表现显著提升;时间上,与基准产品的显著相关区域比例显著增加,且空间连续性增强,尤其体现在中低纬度夏季月份及高纬度非生长季。尽管改进模型在原始雨林区、高纬度寒区(西伯利亚、加拿大北部)和极端干旱区模型的模拟效果提升有限,但通过表征降水空间异质性,文章提出的冠层截留参数化方案在整体上增强了陆面过程模式对水热通量的模拟能力。
Global warming has intensified the spatiotemporal heterogeneity of precipitation,but the typical grid spacing of land-atmosphere coupling models remains much larger than the spatial scale of real precipitation events.This scale mismatch forces models to distribute rainfall uniformly within a grid cell,which can distort rain-rate estimation and subsequently introduce systematic biases into land-surface hydrological simulations.Vegetation canopy interception is particularly sensitive because it is the evapotranspiration component that responds most rapidly to rainfall and directly controls the partitioning of precipitation into interception,evaporation,throughfall,and stemflow,thereby influencing surface energy and water fluxes.In this study,we quantify the global spatiotemporal patterns of rainfall coverage(µ),defined as the fractional area within a model grid cell where rainfall actually occurs.Using bias-adjusted WFDE5 precipitation as the model forcing field and MSWEP V2.8 as the benchmark"actual"precipitation,we derive a globalµdataset at 0.5°spatial resolution and 3-hourly temporal resolution for 1980-2018 and then aggregate it to monthly means for model application.The climatological meanµover 1981-2018 is 0.36,exhibiting strong spatial contrasts:high values occur in equatorial and tropical rainforest regions,whereas low values dominate subtropical arid and desert zones.Seasonally,µfollows the order June-August>December-February>March-May>September-November,with the largest seasonal amplitude in mid-to high-latitude regions of the Northern Hemisphere.We incorporate the monthly varyingµinto the rainfall interception parameterization of Community Land Model version 5(CLM5),thereby representing subgrid precipitation heterogeneity in canopy interception calculations.Offline global simulations were conducted at a 1°resolution for 1980-2018 using the CLM5 Satellite Phenology configuration.The performance of the modified model(CLM5_µ)is systematically evaluated against four widely used global evapotranspiration products that provide canopy interception estimates,including GLEAMv3.5,GLEAMv4.2,PML,and ERA5.The results demonstrate that introducing rainfall coverage substantially improves the realism of the simulated global canopy interception.The multi-year mean interception decreases from 56.66 mm in the baseline CLM5 to 49.13 mm in CLM5_µ,bringing simulations closer to the range of benchmark products.Spatially,the most pronounced improvements occurred in mid-to low-latitude humid and semi-humid regions(e.g.,parts of North America and northern Eurasia)and in arid-to-semiarid transition zones(e.g.,the Sahel and Central Asian grasslands),where the baseline model tended to overestimate interception under the uniform rainfall assumption.Temporally,CLM5_µshows a higher proportion of grid cells with statistically significant correlations to benchmark products and enhanced spatial continuity of correlated areas,especially during summer months in mid-to low latitudes and during non-growing seasons in high-latitudes.Improvements are relatively limited in primary tropical rainforests,high-latitude cold regions(e.g.,Siberia and northern Canada),and extremely arid areas.Overall,this study provides a practical and physically interpretable pathway for incorporating spatial heterogeneity of precipitation into canopy interception parameterization.By accounting for rainfall coverage dynamics,the proposed scheme reduces interception biases induced by scale mismatches and strengthens the capability of land-surface models to represent water and heat flux partitioning on a global scale.
作者
何为
王大刚
He Wei;Wang Dagang(School of Geography and Planning,Sun Yat-sen University,Guangzhou 510275,China)
出处
《热带地理》
北大核心
2026年第3期548-561,共14页
Tropical Geography
基金
国家自然科学基金面上项目(52579030)
广东自然科学基金面上项目(2025A1515011666)。
关键词
陆面过程模式
降雨覆盖度
降雨截留
植被冠层截留
Community Land Model
rainfall coverage
rainfall interception
vegetation canopy interception
