Status and updates on the hyperspectral image archive of DESIS

Abstract

In recent years, spaceborne imaging spectroscopy has made significant progress. The field has evolved from a limited range of instruments and data offer to a broad selection of missions simultaneously acquiring quality data, both in terms of spectral resolution and signal-to-noise-ratio. The spectral information provided by these missions is playing an increasingly important role in our understanding of the Earth’s surface and its dynamic processes, in monitoring the environment and in managing the Earth’s resources. DESIS, launched in June 2018, was the mission that inaugurated this new era, followed by the missions GF-5 (2018), PRISMA (2019), HISUI (2019), EnMAP (2022) and EMIT (2022). Today, DESIS has been in operation for more than 5 years and has acquired by May 2024 over 330.000 images of the Earth. Together with the other imaging spectroscopy missions in orbit, a huge image archive has been created covering many areas multiple times by several instruments. In this presentation, the status of the mission and data access in general will be explained. DESIS, a pushbroom imaging spectrometer that operates in the VNIR range (400 – 1000 nm), uses narrow (2.55 nm) spectral sampling. The spatial resolution is 30 m and the swath width is 30 km while the swath length varies, depending on the planned acquisitions. Users obtain DESIS products processed to different levels and with different processing options. Level 1B products (L1B) correspond to radiometric Top of Atmosphere (TOA) at sensor geometry radiances. Level 1C (L1C) are L1B products that are ortho-rectified. Finally, Level 2A (L2A) are atmospherically corrected orthorectified TOA radiances, providing finally Bottom of Atmosphere (BOA) reflectances. A new data access point has been developed to enable the download of mass data in particular, which is often required for the integration of such data into artificial intelligence and deep learning algorithms. It enables a simple data selection process that include not just DESIS data but also EnMAP and other satellite data available at the DLR GeoService. Furthermore, DESIS data are in the process of getting the CEOS analysis ready data status. DESIS products are being used by a growing user community in a wide range of applications. The large number of DESIS products enables the development of applications that need to be trained on large volumes of data or data acquired under different observation conditions. The huge DESIS data archive is a suitable data source for developing scientific and commercial applications.