Annual Report for the year 2013:

• Main Authors: Solas Irel, Compiled Brian Ward
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2013
• Subjects: Southern Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.675.2534; http://solas-int.org/files/solas-int/content/downloads/Community/National+Networks+2013/SOLAS+Annual+Report+2013_Ireland.pdf

1. Scientific highlights Analysis of the PKT correction for direct CO2 flux measurements over the ocean Eddy covariance measurements of air-sea CO2 fluxes can be affected by cross-sensitivities of the CO2 measurement to water vapour, resulting in order-of-magnitude biases. Well established causes for these biases are (i) cross-sensitivity of the broadband non-dispersive infrared sensors due to band-broadening and spectral overlap (commercial sensors typically correct for this) and (ii) the effect of air density fluctuations (removed by determining the dry air CO2 mixing ratio). Another bias related to water vapour fluctuations has recently been observed with open-path sensors, attributed to sea salt build-up and water films on sensor optics. Two very different approaches have been used to deal with these water vapour-related biases. Miller et al. (2010) employed a membrane drier to physically eliminate 97 % of the water vapour fluctuations in the sample air before it entered a closed-path gas analyser. Prytherch et al. (2010) employed the empirical (Peter K. Taylor, PKT) post-processing correction to correct open-path sensor data. We tested these methods side by side using data from the Surface Ocean Aerosol Production (SOAP) experiment in the Southern Ocean. The air-sea CO2 flux was directly measured with four closed-path analysers