|Project name:||IRDAS-EXP - SWIR Long Range Differential Absorption Experiment for Trace Gas Measurements|
|Project leader:||Peter Bernath (Dept of Chemistry, Univ. of York; IRDAS-EXP prime contractor)|
Gottfried Kirchengast (of WegCenter part; IRDAS-EXP main subcontractor)
|Project team:||Univ. of York:|
Gonzalo G. Abad
Univ. of Manchester:
MPI Biogeochemistry–Validation Support:
IAP Moscow–Scintillation Study Support:
|Partners:||Dept of Chemistry, Univ. of York, York, UK|
School of Chemical Engineering and Analytical Science, Univ. of Manchester, Manchester, UK
Max-Planck-Institute for Biogeochemistry, Jena, DE
Inst. of Atmospheric Physics, Russian Acad. Sciences, Moscow, RU
European Space Agency ESA
The context of the IRDAS-EXP project, a successor project of the IRDAS project, is the infrared-laser occultation technique (LIO), which is a powerful, active occultation method for the measurement of various atmospheric trace gases. This technique exploits narrowband laser signals in the short-wave infrared spectral range (SWIR, 2 um to 2.5 um) to derive the concentrations of a range of trace species, especially greenhouse gases, via differential absorption spectroscopy. The previous projects ACTLIMB and IRDAS showed that the accuracy of trace gas profiles measured using LIO will be very high. In particular, using the signals foreseen for the so-called ACCURATE mission for climate benchmark profiling of greenhouse gases and thermodynamic variables and wind from space, the volume mixing ratios of H2O, CO2 (12CO2, 13CO2, C18OO), CH4, N2O, O3, and CO can be determined accurate to within 1 % to 4 % individual-profile rms error over the upper troposphere and lower stratosphere (UTLS). Together with the high vertical resolution, unbiasedness and good global coverage of the data---characteristics which are intrinsic to the occultation method---the LIO technique is highly complementary to currently operated measurement methods.
In this context the aim of the IRDAS-EXP project is the preparation and conduction of an experiment, including the related analysis of the results, which will demonstrate the LIO technique for the first time. The IRDAS-EXP experiment will be ground based and be performed at an altitude of about 2.4 km between two observatories at the Canary Islands which are about 144 km apart (isles of La Palma and Tenerife). The instrumentation needed, i.e., transmitter and receiver for testing the infrared-laser occultation, is constructed and tested at the Univ. of York, UK, together with the Univ. of Manchester, UK, with scientific support from the Univ. of Graz, AT. Optionally also cameras for additional analysis of the data are considered, focusing on scintillation studies; this part is scientifically supported by the Inst. of Atmospheric Physics, Russian Acad. of Sciences, RU. The measurement campaign, together with related in-situ greenhouse gas measurements for validation supported by the MPI for Biogeochemistry Jena, DE, is foreseen in July 2011. This experiment, focused in terms of parameters on the key species CO2 (12CO2, 13CO2, C18OO), CH4, and H2O, will deliver important insight into the LIO technique and be an essential step towards operation of the LIO technique in space.