New developments in SOLAR2000 for space research and operations Original Research Article

The SOLAR2000 (S2K) project provides solar spectral irradiances and integrated solar irradiance proxies for space researchers as well as ground- and space-based operational users. The S2K model currently represents empirical solar irradiances and integrated irradiance proxies covering the spectral range from the X-rays through the far infrared and has evolved through 23 version releases since October 1999. Variability is provided for time frames ranging from 1947 to 2052. The combination of variability through multiple time periods with spectral formats ranging from resolved emission lines through integrated irradiance proxies is a unique feature that provides researchers and operational users the same solar energy for a given day but in formats suitable for their distinctly different applications. We report on new developments in the SOLAR2000 version 2.24 model. There are several models and reference spectra now included in SOLAR2000 including the S2K extreme ultraviolet (EUV) irradiance model provided by Tobiska (S2K: 1–121 nm), the vacuum ultraviolet (VUV) model provided by Woods (VUV2002: 1–420 nm), and the ASTM-E490 reference spectrum (122–1,000,000 nm). Improved model accuracy in the XUV–EUV spectral regions is obtained with the inclusion of the new TIMED SEE version 7 dataset. We report on integrated irradiance products including some revisions to previously reported proxies, E10.7, QEUV, Peuv, T∞, RSN, and S, and an introduction to seven new integrated irradiance proxies. They include E1_40, XE10.7, Xb10, Xhf, X10.7, ESRC, and ESRB. The Schatten solar dynamo model output is included in the S2K Operational Grade model and provides forecast proxies out to five solar cycles. The SOLAR2000 Research Grade (RG) model provides historical irradiances and proxies for space research and is freely available, via web download, to users of any platform through the use of an IDL virtual machine (VM) graphic user interface (GUI) application. The SOLAR2000 Professional Grade (PG), Operational Grade (OP), and System Grade (SY) models provide historical, nowcast, and forecast irradiances and proxies, including in high time resolution, for ground- and space-based operations; these fee-based applications are available to operational users on any platform through an IDL VM GUI application (S2K PG: daily values), server access (S2K OP: daily plus high time resolution), and rack-mount turn-key (S2K SY: daily plus high time resolution linked with a system of models) configurations. All SOLAR2000 model versions and grades are compliant with the ISO standard 21348 “Space environment (natural and artificial) – process for determining solar irradiances.”