O3 is of crucial importance for the equilibrium of the Earth atmosphere. In the stratosphere, the ozone layer shields the biosphere from dangerous solar ultraviolet radiation. In the troposphere, it acts as an efficient cleansing agent, but at high concentration it also becomes harmful to human and animal health and vegetation. Ozone is an important greenhouse-gas contributor to ongoing climate change. Since the discovery of the Antarctic ozone hole in the mid-eighties and the subsequent Montreal protocol that regulated the production of chlorine-containing ozone-depleting substances, ozone has been routinely monitored from the ground and from space.
Concerning S5P/TROPOMI, there are two algorithms that will deliver total O3 column amounts to be retrieved from S5P/TROPOMI. The first algorithm is based on the DOAS-style GOME Data Processor (GDP) algorithm Version 4.x. The second is based on GDP Version 5, which is a direct-fitting algorithm deployed for the GOME/ERS-2 16-year reprocessing in 2012. The first algorithm is to be used for generation of near-real-time (NRTI) products, while the second one will generate the offline (OFFL) and reprocessed products. Both algorithms are based on O3 absorption in the UV Huggins bands (325-335 nm). In the current version of the product, only the NRTI algorithm is developed and include in the S5P L2 O3 Total Column. The main product parameters (total ozone in [DU], ozone temperature in [K]) are the same in both cases. Both algorithms will also deliver a profile correlation matrix based on a-priori column-classified ozone profile climatology. However, the full L2 O3 Total Column data products will differ in some aspects - this reflects intrinsic differences in the two retrieval algorithms. For example, the NRTI L2 product will contain intermediate output (slant columns, air mass factors) resulting from the two-step DOAS style of retrieval. Both L2 O3 products will output additional diagnostics (ancillary retrieval state vector elements, cloud information), again depending on the style of retrieval.
USER DOCUMENTATION: ATBD
The Algorithm Theoretical Basis Document (ATBD) can be found by clicking here.
PUM & SAMPLE DATA
The Product User Manual (PUM) and Sample Data Files are being updated based on a new release of the processing software and will be available for download by mid-May 2017.
After launch, preliminary product results will be provided during the Commissioning Phase and the Operational Phase.