The Small-Scale Variability of Solar Radiation (S2VSR) Campaign – Overview and first Results

The solar radiation incident at the earth surface is a driving component of the surface energy budget. It often exhibits significant small-scale variability due to its modulation by clouds, in particular for shallow cumulus. This variability limits the representativity of tradiational point-like observations for extended spatial domains such as satellite pixels and model grid boxes. It also causes large fluctuations in power generation by photovoltaic systems.To better characterize this small-scale variability, TROPOS has developed a unique sensor network consisting of 100 autonomous pyranometers which record global radiation, temperature and relative humidity at a frequency of 1-Hz. It is thus capable of resolving fluctuations down to the second and decameter scale, as demonstrated for several past campaigns in Germany. The upcoming S2VSR campaign will deploy 60 of these stations at the Central Facility of the ARM Southern Great Plains site in the United States, distributed across a 6x6 km2 domain during summer 2023.The campaign will offer unique opportunities for the analysis of these data together with operational measurements at the ARM site. This specifically includes high-accuracy surface radiation, active cloud profiling, and the Clouds Optically Gridded by Stereo 4-D cloud product. A comparison with satellite observations from geostationary (GOES-R ABI data at 1-min and 500-m resolution) and polar orbit (Sentinel-2 at 10m) is also planned. The overarching goal is an improved understanding of the small-scale variability and 3D radiative effects of solar radiation. This contribution will present first observations from the ongoing campaign, and give a perspective on future plans.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)