{"id":"d7cccf31-9bb5-4356-88a7-38c5458f052b","title":"A global spatially contiguous solar-induced fluorescence (CSIF) dataset using neural networks (2000-2020)","title_en":"","serial":"","user_limit":"To respect the intellectual property rights, protect the rights of data authors, expand services of the data center, and evaluate the application potential of data, data users should clearly indicate the source of the data and the author of the data in the research results generated by using the data (including published papers, articles, data products, and unpublished research reports, data products and other results). For re-posting (second or multiple releases) data, the author must also indicate the source of the original data.","instructions":"For 0.5 degree dataset, each file contains one year of data for each month (monthly resolution), or every 4 day (4day resolution). These files are named by the years \"OCO2.SIF.clear.daily.yyyy.nc\", where yyyy indicate the year. For 0.05 degree dataset, each file contains one day of year (DOY). The filenames include the year and DOY information \"OCO2.SIF.clear.inst.yyyydoy.v2.nc\", where yyyy indicates the year, and doy indicates the day of year.\n\nFor each DOY, clear daily SIF represents the daily averaged SIF (a good proxy of GPP) during this four day, in which the starting date is indicated by the DOY. The clear daily SIF should be more comparable with satellite observed SIF and should have a better relationship with GPP.","description":"Satellite-retrieved solar-induced chlorophyll fluorescence (SIF) has shown great potential to monitor the photosynthetic activity of terrestrial ecosystems. However, several issues, including low spatial and temporal resolution of the gridded datasets and high uncertainty of the individual retrievals, limit the applications of SIF. In addition, inconsistency in measurement footprints also hinders the direct comparison between gross primary production (GPP) from eddy covariance (EC) flux towers and satellite-retrieved SIF. In this study, by training a neural network (NN) with surface reflectance from the MODerate-resolution Imaging Spectroradiometer (MODIS) and SIF from Orbiting Carbon Observatory-2 (OCO-2), we generated two global spatially contiguous SIF (CSIF) datasets at moderate spatiotemporal (0.05∘ 4-day) resolutions during the MODIS era, one for clear-sky conditions (2000–2017) and the other one in all-sky conditions (2000–2016). The clear-sky instantaneous CSIF (CSIFclear-inst) shows high accuracy against the clear-sky OCO-2 SIF and little bias across biome types. The all-sky daily average CSIF (CSIFall-daily) dataset exhibits strong spatial, seasonal and interannual dynamics that are consistent with daily SIF from OCO-2 and the Global Ozone Monitoring Experiment-2 (GOME-2). An increasing trend (0.39 %) of annual average CSIFall-daily is also found, confirming the greening of Earth in most regions. Since the difference between satellite-observed SIF and CSIF is mostly caused by the environmental down-regulation on SIFyield, the ratio between OCO-2 SIF and CSIFclear-inst can be an effective indicator of drought stress that is more sensitive than the normalized difference vegetation index and enhanced vegetation index. By comparing CSIFall-daily with GPP estimates from 40 EC flux towers across the globe, we find a large cross-site variation (c.v. = 0.36) of the GPP–SIF relationship with the highest regression slopes for evergreen needleleaf forest. However, the cross-biome variation is relatively limited (c.v. = 0.15). These two contiguous SIF datasets and the derived GPP–SIF relationship enable a better understanding of the spatial and temporal variations of the GPP across biomes and climate.","doi":"10.11888/Ecolo.tpdc.271751","projection":"","language":"en","share_type":"online","east":180.0,"west":-180.0,"south":-90.0,"north":90.0,"scale":null,"crs":null,"filesize":60000.0,"share_policy":"a","ts_created":"2021-10-15T09:24:29.475417+08:00","doi_type":"拥有自主知识产权","ts_updated":"2021-10-19T09:21:17.025815+08:00","time_description":"","datas_group":3,"time_description_en":"","data_format":null,"project":[11],"specials":[],"cite":null,"review_status":5,"review_invite":[{"user_name":"唐文君","username":"tangwjitp","email":"tangwj@itpcas.ac.cn","is_cancel_expert":false}],"review_editor":{"id":42421,"last_login":"2022-04-08T15:16:51.670544+08:00","username":"任慧霞","email":"510727846@qq.com","is_active":true,"is_staff":true,"user_name":"任慧霞"},"data_sources":null,"temporal_resolution":"Daily","spatial_resolution":"1km - 10km","license":"Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","fund":[],"subtopics":{"metadata":"d7cccf31-9bb5-4356-88a7-38c5458f052b","three_pole":null,"third_pole":null},"username":"张尧","review_time":null,"protected_duration":null,"protected_describe":null,"is_important":false,"hit_count":427}