Accurate estimation of the gross primary production (GPP) of terrestrial vegetation is vital for understanding the global carbon cycle and predicting future climate change. Multiple GPP products are currently available based on different methods, but their performances vary substantially when validated against GPP estimates from eddy covariance data. This paper provides a new GPP dataset at moderate spatial (500 m) and temporal (8-day) resolutions over the entire globe for 2000–2016. This GPP dataset is based on an improved light use efficiency theory and is driven by satellite data from MODIS and climate data from NCEP Reanalysis II. It also employs a state-of-the-art vegetation index (VI) gap-filling and smoothing algorithm and a separate treatment for C3/C4 photosynthesis pathways. All these improvements aim to solve several critical problems existing in current GPP products. With a satisfactory performance when validated against in situ GPP estimates, this dataset offers an alternative GPP estimate for regional to global carbon cycle studies.
2021-10-16
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.
2021-10-15
该数据集包括中国2001~2018年月尺度或年尺度的地表短波波段反照率、植被光合有效辐射吸收比、叶面积指数、森林覆盖度和非森林植被覆盖度、地表温度、地表净辐射、地表蒸散发、地上部分自养呼吸、地下部分自养呼吸、总初级生产力和净初级生产力。空间分辨率为0.1°。此外，还包括在气候驱动下（无人类干扰）的以上11个生态系统参量在2001~2018年间的时空变化。因此，该数据集可以反映气候变化与人类活动对21世纪中国陆地生产系统的影响。
2021-08-31
该数据集是基于16个动态全球植被模式（TRENDY v8）在S2情景下（CO2+Climate）模拟的GPP，表征生态系统总初级生产力。数据来源于Le Quéré et al. (2019)，具体信息和方法参见文章。源数据范围为全球，本数据集选取了青藏高原区域，空间上用最近邻方法插值到0.5度，时间上保持了原有的月尺度。该数据集是标准的模型输出数据，常被用作评定总初级生产力的时间和空间格局，且与其它遥感观测、通量观测等数据进行比较和参考，具有实际意义和理论价值。
2021-05-15
PML_V2陆地蒸散发与总初级生产力数据集，包括总初级生产力（gross primary product, GPP），植被蒸腾（vegetation transpiration, Ec），土壤蒸发（soil evaporation, Es），冠层截流蒸发（vaporization of intercepted rainfall, Ei）和水体、冰雪蒸发（ET_water），共5个要素。数据格式为tiff，时空分辨率为8天、0.05°，时间跨度为2002.07-2019.08。 PML_V2在Penman-Monteith-Leuning (PML) 模型的基础上，根据气孔导度理论，耦合了GPP过程。GPP与ET相互制约、相互限制，使得PML_V2在ET模拟精度，相对于以往的模型有很大的提升。PML_V2的参数分不同的植被类型，在全球95个涡度相关通量站上率定。其后根据MODIS MCD12Q2.006 IGBP分类，将参数移植至全球。PML_V2采用GLDAS 2.1的气象驱动和MODIS 叶面积指数(LAI)、反射率(Albedo)，发射率(Emissivity)为输入，最终得到PML_V2陆地蒸散发与总初级生产力数据集。
2020-01-05
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