First glimpse of solar induced chlorophyll fluorescence (SIF) from the Orbiting Carbon Observatory-2.
Abstract:In the past few years, space-borne retrievals of solar induced chlorophyll fluorescence, or SIF, have been enabled by the GOSAT, SCIAMACHY and GOME-2 satellite. Initial studies demonstrate that SIF often has a direct relationship with gross terrestrial carbon uptake, and therefore provides a complementary view of the carbon cycle to that provided by column carbon dioxide (XCO2) measurements. Accurate estimates of SIF have also been shown to be necessary for bias free estimates XCO2 itself. The OCO-2 O2 A-band channel allows us to perform SIF retrievals, and pre-launch sensitivity studies indicated that OCO-2 will provide an unprecedented SIF dataset along its orbit track, albeit at the expense of coverage. Compared to GOSAT, it will record 100 times more SIF data, which will significantly reduce the large random errors in present in GOSAT-based global maps of SIF.
Here, we will show first SIF results from OCO-2 data with an initial comparison to previous retrievals from GOSAT. Owing to the low computational demand and relative simplicity of the SIF retrieval algorithm, we expect SIF data to mature somewhat earlier than the more complex XCO2 product. The focus of this presentation will be on quantifying the retrieval quality, showing potential issues, providing a comparison with cloud flags, and presenting the first global maps of SIF from OCO-2.