ChinaSpec collaborates with  other communities, and shares ground spectral and SIF data acquired from the sites of the network. This website (http://chinaspec.nju.edu.cn) is the platform for releasing the related information and sharing datasets of the sites registered in the ChinaSpec network since 2016 when the first dataset was collected. The dataset consists of metadata of each site, reflectance covering spectral range from 400 nm to 1000 nm (if available), retrieved SIF with two methods (3FLD and SFM) after data quality control. A few sites could also share EC measured data (includes CO2, H2O and energy fluxes, as well as meteorological measurements such as radiation, air temperature, relative humidity, precipitation, wind speed and direction), but EC flux data at most sites are generally shared through ChinaFLUX network (Yu et al., 2006; Yu et al., 2010). The temporal scale of the dataset is half hourly, which is processed from high frequency raw data (~1 minute for spectral data).

ChinaSpec provides continuous in situ SIF and reflectance measurements across multiple ecosystems in China to the broad community of scientists who need ground observations to improve the understanding the controls on the biosphere-atmosphere fluxes of carbon and water vapor based on remote sensing approaches, especially on the SIF observations. As all sites are operated by their own funding of PIs, the ChinaSpec dataset only provide the dataset that PIs who give us the permission to share their datasets over these SIF measurement sites in China. We hope that this platform and dataset shared by ChinaSpec network will promote the developments of the methods and data quality of spectral measurements, and enable a new perspective of integrating spectral and EC measurements with the aim to increase the quality of the research and the collaboration on ecology and optical remote sensing communities.

The data usage polices for ChinaSpec is similar to that for FLUXNET dataset (especially the FLUXNET2015 Dataset). The use of spectral data in ChinaSpec will follow “the fair use policy” (https://fluxnet.fluxdata.org/). In other words, the ChinaSpec datasets are open and freely available for scientific and educational purposes by any registered user after acceptance of a proposal (at least 200 words to describe the intention of using this dataset) submitted to the steering committee. That is, data users submit a small proposal on the intended use of the data before they download the data; this intended-use statement will be emailed to the data producer(s) of the sites. This policy means that “(1) data producers are informed of who uses the data and for what purpose and (2) that proper acknowledgment and citations are given to all data used in a peer reviewed publication, via the following protocols: providing a co-authorship to the site PIS or at least a citation of a publication for each site”.  It is requested that every publication specifies each site used with the data-years used and brief acknowledgment for funding (if provided by ChinaSpec PI) in the text. We recommended the users to contact the site PIs before publishing to avoid potential misuse or misinterpretation of the data. In particular, if a work is based on the SIF data from only a few sites, it is strongly recommended to contact the site PI about coauthorship or proper acknowledgment for their contribution.

The distribution of the data for each site will be shared after the first publication or two years later after data collections. At this stage, the data we share for each site is ground far-red SIF (760 nm) retrievals with 3FLD and SFM algorithms and vegetation indices (e.g., NDVI, EVI, and PRI depending on sites) at half-hourly time scales.  Since the year of 2019, we have distributed the spectral dataset including reflectance and SIF for 1-2 years from 6 sites. The rest of the spectral dataset will be regularly updated with data from new site years.