Ground based remote sensing of atmospheric greenhouse gases using mobile FTIR spectrometers
|Other Titles:||Bodengebundene Fernerkundung atmosphärischer Treibhausgase unter Benutzung mobiler FTIR Spektrometer||Authors:||Petri, Christof||Supervisor:||Notholt, Justus||1. Expert:||Notholt, Justus||2. Expert:||Ladstätter-Weissenmayer, Anette||Abstract:||
This work was performed at the Institute for Environmental Physics (IUP) at the University of Bremen and is divided into five parts, all referring to ground based solar absorption measurements of CO and the greenhouse gases CO 2 and CH 4 . After an introduction in chapter 2, two modifcations are discussed in chapter 3 to further improve the precision of the already well organized TCCON network. TCCON performs and provides high precision total column measurements of greenhouse gases for validating satellites, in particular OCO-2. A possible inconsistency within the phase correction during processing the spectra from the recorded interferograms was found. This could lead to irregular intensities in the spectra, separated for forward and reverse scans. For the a?ected sites, this lead to a split up of the retrieved results between forward and reverse scans of up to 1.5%, which is not acceptable for a network performing high precision data products. The issue could be fixed by modifying a parameter within the processing. Secondly an error in the time recording of the FTIR spectrometer, used within TCCON and NDACC, could be found. The timing issue lead to an error in the retrieved results within the precision of the measurements of a 0.2%, but still would increase the precision if avoided. For our automated TCCON sites, we now take the measurement time from the log files instead of the time recorded from the instrument. Chapter 4 is about including smaller mobile instruments to improve the latitudinal and longitudinal coverage and to measure with higher spatial resolution in areas of interest. To achieve this, it is desirable to increase the number of measurement sites in a cost-effective way. This work demonstrate the possibility to use smaller mobile FTIR instruments as supplement to the high standard FTIR measurement networks NDACC and TCCON. Two similar mobile high resolution spectrometer and two low resolution pendulum spectrometer have been successfully tested. In chapter 5, the prospects of a rapid data delivery are discussed, which could be performed within this work and which is already used to improve the quality of forecast models. The rapid data delivery has been set up for our TCCON sites in Orleans and Bialystok first, now also Bremen and Ny-A lesund could be included. Within chapter 6, the CO data product of the two networks NDACC and TCCON are compared in accuracy, precision and sensitivity. A different response behavior on higher CO concentrations has been found and is discussed. Finally in chapter 7, results from the mobile instruments Bruker IFS120-5M in Paramaribo, Suriname and the Bruker IFS125M in Kourovka, Russia are discussed as potential supplement to TCCON data, in regions where TCCON is not present. A CH 4 event has been identified with the retrieved data from Kourovka, and could be verified with satellite measurements from the GOSAT satellite. The cause of the enhancement could be a natural blowout, which sometimes take place in Siberia but usually not in this area, or a huge leakage of a gas pipeline.
|Keywords:||FTIR, greenhouse gas, atmospheric, remote sensing, phase correction||Issue Date:||7-Dec-2017||URN:||urn:nbn:de:gbv:46-00106266-16||Institution:||Universität Bremen||Faculty:||FB1 Physik/Elektrotechnik|
|Appears in Collections:||Dissertationen|
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