GOSIF - Global, OCO-2 based SIF product

Solar-induced chlorophyll fluorescence (SIF) brings major advancements in measuring terrestrial photosynthesis. Many studies showed strong relationships between coarse-resolution SIF data (e.g., GOME-2, GOSAT) and gridded GPP (gross primary productivity) data. More recently, several studies have evaluated the potential of SIF retrievals from the Orbiting Carbon Observatory-2 (OCO-2) in estimating GPP using discrete SIF soundings from OCO-2 and GPP data from eddy covariance (EC) flux towers. However, the spatially and temporally sparse nature of OCO-2 data makes it challenging to use these data for many applications from the ecosystem scale to the globe. We developed a global ‘OCO-2’ SIF data set (GOSIF) with high spatial and temporal resolutions (i.e., 0.05°, 8-day) over the period 2000-2020 based on discrete OCO-2 SIF soundings, remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS), (MODIS), and meteorological reanalysis data using a data-driven approach. The GOSIF product has reasonable seasonal cycles, and captures the similar seasonality as both the coarse-resolution OCO-2 SIF (1°) directly aggregated from the discrete OCO-2 soundings and tower based GPP. Our SIF estimates are highly correlated with GPP from 91 FLUXNET sites (R2 = 0.73, p < 0.001). They capture the expected spatial and temporal patterns in SIF and also has a remarkable ability to highlight the crop areas with the highest daily productivity across the globe. Our product also allows us to examine the long-term trends in SIF globally. Compared with the coarse-resolution SIF that was directly aggregated from OCO-2 soundings, GOSIF has finer spatial resolution, globally continuous coverage, and a much longer record. Citation: Li, X., Xiao, J. (2019) A global, 0.05-degree product of solar-induced chlorophyll fluorescence derived from OCO-2, MODIS, and reanalysis data. Remote Sensing, 11, 517; doi:10.3390/rs11050517. Metadata: Spatial resolution: 0.05 degree Spatial extent: globe Temporal resolution: 8 day Temporal extent: 2000 - 2020 Fair Data Use Policy: We make this data product available to the research community as we believe that the dissemination of this data set will lead to advancement in science. If you plan to use our data in a manuscript or presentation, we request that you inform us at an early stage of your work. If this data set is essential to your work, or if an important result or finding depends on the GOSIF data, co-authorship may be appropriate. You must inform us of your analysis and publication plans well in advance of submission of a paper, give us an opportunity to read and intellectually contribute to the manuscript, and, if appropriate, offer co-authorship. Contact: Drs. Jingfeng Xiao ([e-mail]) and Xing Li ([e-mail]).