PT Journal AU Hase, F Frey, M Kiel, M Blumenstock, T Harig, R Keens, A Orphal, J TI Addition of a channel for XCO observations to a portable FTIR spectrometer for greenhouse gas measurements SO Atmospheric measurement techniques PY 2016 BP 2303 EP 2313 VL 9 IS 5 DI 10.5194/amt-9-2303-2016 LA english ER