CPA Postdoc L(a)unch – July 28
- Public Event
Dr. Saswati Das
Evaluating Satellite-based XCO2 measurements from OCO-2 against Ground-based TCCON and COCCON measurements
Lunch will be provided starting 11:45 AM!
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Evaluating Satellite-based XCO2 measurements from OCO-2 against Ground-based TCCON and COCCON measurements
Carbon dioxide (CO2) is the primary greenhouse gas emitted into the atmosphere due to anthropogenic activities. While CO2 is naturally present in Earth's carbon-cycle, human activities strongly influence and alter the carbon-cycle by impacting the ability of natural sinks to reduce atmospheric-CO2. This necessitates the precise, accurate, and long-term measurements of CO2, accomplished through satellite and ground-based CO2 measurements.
The Orbiting Carbon Observatory-2 (OCO-2) was launched in 2014. It is NASA's first Earth-orbiting satellite dedicated to making observations of CO2 in the atmosphere and measuring its column-averaged dry-air mole fraction (XCO2). The primary goal of the OCO-2 mission is to provide XCO2 measurements with sufficient precision and accuracy to quantify carbon cycle fluxes at regional scales, alongside quantifying its seasonal and interannual variability.
In this work, we evaluate the new and improved version 11 (V11) of OCO-2 data by comparing it against independent data sets to identify potential biases and errors and establish its robustness for use by the science community. In the past, ground-based accurate and precise column-averaged measurements of XCO2 from the Total Carbon Column Observing Network (TCCON) have been used in validating OCO-2 measurements. More recently, measurements of greenhouse gases have become available from the COllaborative Carbon Column Observing Network (COCCON), using portable Fourier-Transform InfraRed (FTIR) spectrometers (EM27/SUN). With several global sites, both TCCON and COCCON serve as suitable independent validation data sets to compare against satellite-based XCO2 measurements from OCO-2.
Comparison of OCO-2 measurements against selected TCCON and COCCON sites indicate that the absolute average bias values are close to 0 ppm for TCCON and less than 0.8 ppm for COCCON in the Land Nadir/Glint and Target mode observations. We evaluate the differences between the V11 OCO-2 and validation data sets.