Studies on the Transport of CO and Related Biomass Burning Emissions Using Ground-based Fourier Transform Infrared Spectrometry

Abstract

This work deals with measurements and analysis of solar absorption spectra of atmospheric trace gases in the infrared spectral region, as recorded by a Fourier transform infrared (FTIR) spectrometer. The aim of this work is to study the transport of biomass burning emissions in the free troposphere, as well as its impact on the mid and high latitude atmospheres. The first part of this work involves the analysis of spectra from measurements performed in the high Arctic at the NDSC (Network for the Detection of Stratospheric Change) station in Ny Ǻlesund, Spitsbergen (79Ã ° N, 12Ã ° E). After a short introduction to FTIR, it will be shown that the retrievals of several trace gases especially carbon monoxide (CO) have been improved and characterized, in order to yield usable profile information. The second part of this work deals with measurements of CO profiles on board the German research vessel Polarstern. The measurements were taken during a ship cruise across the Atlantic, yielding altitude as well as latitudinal information on trace gases. The measurements of CO profiles have been combined with trajectory analyses and fire count data from satellites, in order to obtain a better understanding of the transport of biomass burning emissions and pollution in the troposphere. Furthermore, the measurements were validated using data from the MOPITT satellite and simulations from the Model of Atmospheric Transport and Chemistry of the Max Planck Institute in Mainz, Germany. The result is one of the first formal validations of real FTIR profile data with satellite and model, as well as a better illustration of the transport of pollution over the Atlantic. The third part of this work is a collaboration with different institutes worldwide to achieve a quantitative assessment of the CO anomaly in the northern hemisphere brought about by widespread biomass burning events in 1998. The study was done using total columns of CO retrieved from FTIR and surface CO from in situ measurements. This is combined with a study on fire counts measured by the MODIS instrument and fire studies from government inventories. Measurements of HCN and C2H6, also biomass burning products, were also analyzed to complement the CO measurements. The fourth part of this work takes advantage of the increased altitude information that was achieved through the optimization of the retrieval methods. This part shows and establishes that FTIR spectrometry enables the detection of columns of strato-mesospheric CO, which consists of the columns in the layer between from 18 km and 100 km (stratosphere to upper mesosphere). With this information, an old data set from 1992 in Ny Ǻlesund turned into the longest ground-based measurements of strato-mesospheric CO ever published. As a result, new information on the nature of the transport and variability of strato-mesospheric CO have been uncovered.The last part of this work discusses the results of a recent and on-going campaign in the tropics (Paramaribo, Suriname, 5.8Ã ° N, 55.2Ã ° W). The results shown here focus on the measurements of enhanced CO and HCN values and the effect of the migration of the ITCZ (Inter-tropical Convergence Zone) over the measurement site.