Diffusely Transmitted Downward PAR Surface Solar Irradiance for Himawari-8/9 (HIM_SSI_PAR_Diffuse) 

As part of the downward surface solar irradiance (SSI) collection, this product is the diffusely transmitted irradiance integrated over the PAR (Photosynthetically Active Radiation) spectral range (400 to 700 nm). The product was generated for daytime Himawari-8/9 imagery using the Qin et al. (2021a) algorithm for the Australian continent and surrounding waters. While it is provided here in a regular latitude/longitude grid, the product is also available in the original Himawari (geostationary) projection (WGS84, sub-satellite longitude = 140.7°E and satellite altitude = 35785863 meters). Please contact the authors for accessing the data, which is located on the Australian National Computational Infrastructure (NCI). Currently, a near-real-time algorithm/processor is being developed to improve data availability, and to extend production to Himawari-10 (2028-2045). 

We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. We at the Terrestrial Ecosystem Research Network (TERN) acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. This work was funded by TERN, an Australian Government NCRIS (National Collaborative Research Infrastructure Strategy) enabled project, and is supported using TERN infrastructure. The research was undertaken at CSIRO (Commonwealth Scientific and Industrial Research Organisation) collaboratively among research units (Environment, Energy, Agriculture and Food). The authors acknowledge the resources and services received from NCI and CSIRO HPC (High Performance Computing). We appreciate the support by Japan Meteorology Agency (JMA) and Australian Bureau of Meteorology (BoM) in providing Himawari data. 

The Himawari satellite series offers a unique opportunity to monitor sub-daily processes on Earth and in its atmosphere over Asia and Oceania, due to its unprecedented 10-minute temporal resolution as well as improved spatial and spectral resolutions compared to the previous generations of Japanese geostationary satellites and sensors (i.e., MTSAT series) which Australian researchers are kindly provided access through a JMA-BoM agreement. This product provides an instantaneous estimation of the photosynthetically active portion (PAR) of the diffusely transmitted downward surface solar irradiance (W/m²) every 10 minutes on a pixel (~2 km) level. Here “diffuse” means the solar irradiance was scattered at least once by the atmosphere before reaching the Earth’s surface in downward direction. “PAR” means the irradiance was integrated with respect to wavelength from 400 nm to 700 nm when the sun is 15° above the horizon. Together with the total and directly transmitted component (HIM_SSI_PAR_Total & HIM_SSI_PAR_Direct), this product may be used, for example, in assessing plant health and productivity in agriculture and forestry, in monitoring and mitigating environmental impacts, and in improving climate models. 

As part of the downward surface solar irradiance (SSI) collection, this product was generated using an algorithm independently developed by CSIRO based on radiative transfer, using the cloud properties products generated by Qin et al. (2019). Discussion of the algorithm can be found in Qin et al. (2021a, 2021b and 2022).