贾根锁研究员在国际科学理事会（ICSU）第118次执委会会议上当选其亚太区域委员会 (RCAP)委员，同时担任区域灾害风险工作组成员 (详见中国科协简讯 | 中国科学院简讯)。

贾根锁研究员被政府间气候变化专门委员会(IPCC) 遴选为《气候变化与陆地特别报告》(SRCCL) 的主要作者协调人(CLA)，负责协调和撰写报告第二章-陆地与气候相互作用(Land-climate interactions) (详见IPCC SRCCL | 简讯)。

第四次《气候变化国家评估报告》撰写工作近日启动。贾根锁研究员被聘任为报告首席专家之一，负责“土地覆盖变化以及对气候变化的影响”部分的编写协调工作。

中国科学院战略先导专项A类-地球大数据科学工程(CASEarth, 2018-2022)正式启动，贾根锁研究员担任专项方案规划工作组组长、以及项目三课题四负责人 (详见专项主页)。

2017年2月，联合国环境署启动了全球环境展望(GEO-6)全球评估报告进程，中国科学院大气物理研究所贾根锁研究员被遴选为主要作者协调人(CLA)，负责协调和撰写第八章-陆地环境。

数字一带一路（DBAR）国际科学计划启动，这一大型国际科学计划基于空间观测科学认知“一带一路”，旨在为“一带一路”建设提供科学、开放和合作的可持续发展信息决策支持。贾根锁研究员当选DBAR国际科学计划科学委员会委员和环境变化工作组共同主席（详见《数字一带一路科学规划》发布）。

1. Improving meteorological drought monitoring capability over tropical and subtropical water-limited ecosystems: evaluation and ensemble of the Microwave Integrated Drought Index
   Zhang, A., G. Jia*, H. Wang. Environmental Research Letters: 2019 ,14(4) ,044025, doi: 10.1088/1748-9326/ab005e 摘要  The monitoring of meteorological drought is critically important for tropical and subtropical water- limited ecosystems, which play key roles in the global carbon cycle and ecosystem services. Satellite remote sensing is the only practical approach for tracking drought changes with high resolution and an instantaneous response. However, the application of remote sensing drought indices derived from optical and infrared bands has been constrained due to cloud contamination. Here the Microwave Integrated Drought Index (MIDI), a multi-sensor microwave remote sensing drought index integrating state-of-the-art multiple satellite microwave-derived precipitation, soil moisture and land surface temperature information, was processed to improve the meteorological drought monitoring capability of satellite remote sensing. The index was evaluated against the 1 to 12 month field-based drought indicators Standardized Precipitation Index (SPI) and Standardized Precipitation Evapo- transpiration Index (SPEI) and anomalies in the satellite-derived Enhanced Vegetation Index (EVI) from 1998 to 2014. MIDI with an optimal ensemble of multiple satellite precipitation products showed a better improvement in meteorological drought monitoring capability than MIDI based on an individual satellite precipitation dataset, and had statistically strong correlation in particular with 1 month SPI/SPEI over a wide range of bio-climatic zones spanning from arid to humid. Moreover it showed significantly higher correlations with EVI anomalies than SPI/SPEI. The results demonstrated the reliability and superiority of MIDI in monitoring meteorological drought with the ability to work in all weather conditions. Therefore, MIDI provides a gateway to employing satellite microwave remote sensing for reliable meteorological drought monitoring, with the potential for long-term drought assessments as well as near-real-time drought monitoring using operational satellites.
2. Seasonal and interannual variations in carbon fluxes in East Asia semi-arid grasslands
   Zhao, H., G. Jia*, H. Wang, A. Zhang, X. Xu. Science of Total Environment: 2019 ,668 ,1128-1138, doi: 10.1016/j.scitotenv.2019.02.378 摘要  Semiarid regions have substantial interannual variation in carbon exchange between terrestrial ecosystem and atmosphere but the diverse responses of carbon fluxes to climate variability are poorly known. We compared carbon exchange processes and the responses to environmental factors in a meadow steppe at Tongyu (TY) and a typical steppe at Maodeng (MD) using long-term continuous eddy covariance measurements. TY precipitation was 25% greater than MD. Both grasslands had interannual fluctuations of carbon sink and source and acted as weak carbon sinks averagely (−22.9 ± 41.0 gCm−2 yr−1 for TY and − 11.8 ± 45.0 gCm−2 yr−1 for MD). The seasonal dynamics of carbon fluxes were significantly related to water availability at MD but more strongly related to air temperature at TY. During dry years, the controlling effect of water availability on carbon fluxes increased. Summer precipitation and soil moisture played key roles in the interannual variations in carbon fluxes in both grasslands. At MD, net carbon uptake was negatively related to summer air temperature likely because warming induced water deficit decreased photosynthesis. Greenness index derived from PhenoCam images captured key phenological phases and diverse magnitude of canopy dynamics. The index was correlated with seasonal and annual variations in carbon fluxes at both grasslands, suggesting the potential of PhenoCam for monitoring the spatial and temporal variations in canopy dynamics in different semiarid grasslands.
3. The contribution of intensified urbanization effects on surface warming trend in China
   Shi, Z., G. Jia*, Y. Hu, Y. Zhou. Theoretical and Applied Climatology: 2019 ,in press ,doi: 10.1007/s00704-019-02892-y 摘要  Historical temperature records are often partially biased by the urban heat island (UHI) effect. However, the exact magnitude of these biases is an ongoing, controversial scientific question, especially in regions like China where urbanization has greatly increased in recent decades. Previous studies have mainly used statistical information and selected static population targets, or urban areas in a particular year, to classify urban-rural stations and estimate the influence of urbanization on observed warming trends. However, there is a lack of consideration for the dynamic processes of urbanization. The Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) are three major urban agglomerations in China which were selected to investigate the spatiotemporal heterogeneity of urban expansion effects on observed warming trends in this study. Based on remote sensing (RS) data, urban area expansion processes were taken into consideration and the relationship between urban expansion rates and warming trends was investigated using data from 975 meteorological stations throughout China. Although urban areas constitute less than 1% of land in China, more than 90% of the meteorological stations experienced urban land use change and the average urban expansion rate was 0.33%/a. There was also a significant positive relationship between observed warming trends and urban expansion rates. Background warming, without the influence of urbanization and extra warming induced by urbanization processes, was estimated using a linear regression model based on observed warming trends and urban expansion rates. On average, urbanization led to an additional annual warming of 0.034 ± 0.005 °C/10a. This urbanization warming effect was 0.050 ± 0.007 °C/10a for minimum temperatures and 0.008 ± 0.004 °C/10a for maximum temperatures. Moreover, it appeared that urbanization induced greater warming on the minimum temperature during the cold season and maximum temperature during the warm season.
4. Decadal decline of summer precipitation fraction observed in the field and from TRMM satellite data across the Mongolian Plateau
   Qin, F., G. Jia*, J. Yang, Y. Na, Y. Bao. Theoretical and Applied Climatology: 2019 ,137(1-2) ,1105-1115, doi: 10.1007/s00704-018-2655-6 摘要  Shifts in precipitation regimes have been given increased attention along with climate trends in the arid and semiarid Mongolian Plateau (MP), because precipitation is the dominant factor that controls vegetation growth and land-use practices in the region. However, the temporal variability and spatial heterogeneity of decadal trends in summer precipitation fraction have not been well understood. In this study, the temporal variability and spatial heterogeneity of annual and summer precipitation change were investigated with the major focus on the summer precipitation fraction across the entire MP, using monthly precipitation data from 141 meteorological stations and the Tropical Rainfall Measuring Mission (TRMM) precipitation data. The Mann–Kendall trend test, Sen’s regression, and Spatial Analyst methods were used for time series analysis. Results show that the regional summer precipitation fraction declined significantly at a rate of − 1.0%/decade (p < 0.05) during 1961–2010, which was supported by TRMM satellite data with a rate of − 2.86%/decade over 1998–2016. Interestingly, rates of decrease in the summer precipitation fraction varied by ecoregion. Spatially, trend in summer precipitation fraction was very heterogeneous, with significant decreasing trends in the eastern typical steppe and southeastern agro-pastoral ecotone, but increasing trends in the southwestern desert and Gobi desert region. In conclusion, the summer precipitation fraction declined because of the asymmetric decreasing or increasing rates in summer and non-summer precipitation during both 1961–2010 and 1998–2010. This implies a major shift of precipitation regime in the region. This is likely driven by decadal changes of the East Asia monsoon system.
5. Urban heat island impacts on building energy consumption: A review of approaches and findings
   Li, X., Y. Zhou, S. Yu, G. Jia, H. Li, W. Li. Energy: 2019 ,174 ,407-419, doi: 10.1016/j.energy.2019.02.183 摘要  Urban heat island (UHI) could have significant impacts on building energy consumption by increasing space cooling demand and decreasing space heating demand. However, the impacts of UHI on building energy consumption were understudied due to challenges associated with quantifying UHI-induced temperature change and evaluating building energy consumption. In this study, we reviewed existing literature for improving the understanding of UHI impacts on building energy consumption. It was found that UHI could result in a median increase of 19.0% in cooling energy consumption and a median decrease of 18.7% in heating energy consumption. The reported UHI impacts showed strong intercity variations with an increase of cooling energy consumption from 10% to 120% and a decrease of heating energy consumption from 3% to 45%. The UHI impacts also showed clear intra-city variations with stronger impacts in urban center than that in urban periphery. There were significant differences in the method and the data used to evaluate the UHI impacts in previous studies. Four future research focuses were recommended to better understand the UHI impacts on building energy consumption.