Drought risk of global terrestrial gross primary productivity in recent 40 years detected by a remote sensing-driven process model

Gross primary productivity (GPP) is the largest flux in the global
terrestrial carbon cycle and affected by multiple factors. In recent
decades, drought has significantly impacted global terrestrial GPP and
been projected to occur with increasing frequency and intensity. However,
the drought risk of global terrestrial GPP has not been well investigated.
In this study, global terrestrial GPP over the period from 1981 to 2016
was simulated with the process-based Boreal Ecosystem Productivity
Simulator (BEPS) model. Then, the drought risk of terrestrial GPP was
quantified as the product of frequency of drought and reduction of GPP
caused by drought, which were determined using the standardized
precipitation evapotranspiration index (SPEI). During the study period,
the drought risk of terrestrial GPP exhibited detectable spatial
heterogeneity, high in southeastern United States, most of South America,
southern Europe, central and eastern Africa, eastern and southeastern
Asia, and eastern Australia. In these regions, the maximum reduction of
GPP might be above 30% in drought years relative to that in normal years.
The drought risk of GPP was low at high latitudes of the Northern
Hemisphere, in which terrestrial GPP increased slightly in drought years.
The spatial pattern of the drought risk of GPP simulated by the BEPS model
was close to that of FLUXCOM GPP, which was scaled from tower observations
with a machine learning algorithm forced by remote sensing and
meteorological data. This study advances our understanding on the impact
of drought on terrestrial GPP over the globe.

总初级生产力（Gross Primary Productivity, GPP）是全球陆地碳循环中最大的通量项，且受多种因素共同调控。近数十年来，干旱已对全球陆地GPP造成显著影响，且未来其发生频率与强度均呈上升趋势。然而，目前学界对全球陆地GPP的干旱风险尚未开展充分研究。
本研究采用基于过程的北方生态系统生产力模拟器（Boreal Ecosystem Productivity Simulator, BEPS）模型，模拟了1981至2016年期间的全球陆地GPP。随后，以标准化降水蒸散指数（Standardized Precipitation Evapotranspiration Index, SPEI）确定干旱发生频率与干旱导致的GPP降幅，将二者的乘积作为陆地GPP干旱风险的量化指标。
研究期内，全球陆地GPP的干旱风险呈现出显著的空间异质性：美国东南部、南美洲大部分区域、欧洲南部、非洲中部与东部、亚洲东部及东南部、澳大利亚东部的干旱风险较高。在上述区域，干旱年份的GPP较正常年份最大降幅可达30%以上。
北半球高纬度地区的GPP干旱风险较低，该区域内干旱年份的陆地GPP甚至出现小幅上升。
本研究通过BEPS模型模拟得到的GPP干旱风险空间分布格局，与基于塔基观测数据、结合遥感与气象数据驱动的机器学习算法进行尺度转换得到的FLUXCOM GPP的分布格局高度吻合。
本研究深化了学界对全球范围内干旱对陆地GPP影响的认知。

搜集汇总

背景与挑战

背景概述

该数据集基于BEPS模型模拟了1981年至2016年全球陆地总初级生产力（GPP），并利用标准化降水蒸散指数（SPEI）量化了GPP的干旱风险，表现为干旱频率与GPP减少量的乘积。研究发现干旱风险存在空间异质性，高风险区域包括美国东南部、南美洲大部、欧洲南部等地，GPP在干旱年份可能减少30%以上，而北半球高纬度地区风险较低。数据集包含年SPEI和GPP的MAT文件，用于支持全球碳循环和干旱影响研究。