Abstract Details


Name: Megha A
Affiliation: Manipal Centre for Natural Sciences (MCNS), MAHE, Manipal
Conference ID: TVS202510275
Title: The SUIT Index: Full-disk Mg II core-to-wing ratio
Authors and Co-Authors: Atul Bhat, Sreejith Padinhatteeri, Durgesh Tripathi, K. Sankarasubramanian
Abstract Type: Contributory Presentation
Abstract: Solar ultraviolet irradiance modulates photochemistry of the Earth’s atmosphere and influences the climate. The Mg II h and k core-to-wing ratio, also known as the Mg II index, is a widely used proxy for this UV variability. However, the existing records are Sun-as-a-star observations and do not reveal the spatial sources of variation. Here we present the first disk-resolved Mg II index, derived from Aditya-L1/SUIT full-disk imaging in four narrow bands around Mg II h & k lines. We construct the pixel-level index maps from weighted core (NB03, NB04) and wing (NB02, NB05) signals and characterize the spectral overlap between NB03 and NB04, which is more pronounced near the line cores. We outline the map-construction workflow, quantify sensitivity to passband overlaps, and validate with reference spectra from GOME and IRIS, convolved with SUIT filter profiles. We show that the daily sequences yield regional indices for plages, sunspots, and quiet Sun, and their spatial averages co-vary with the Bremen composite, providing continuity with legacy proxies while adding spatial attribution. By bridging resolved magnetic-feature evolution with global Mg II variability, the SUIT product delivers a spatially explicit UV proxy suited to irradiance reconstruction and space-weather applications.