Carbon dioxide and water vapour characteristics on the west coast of Arabian Sea during Indian summer monsoon

Carbon dioxide, water vapour, air temperature and wind measurements at 10 Hz sampling rate were carried out over the coast of Arabian Sea, Goa (15°21′N, 73°51′E) in India. These observations were collected, in association with the surface layer turbulent parameters for the Arabian Sea Monsoon Experiment (ARMEX). In the summer monsoon period, concentration of CO2 was in the range of 550–790 mg m − 3 whereas the water vapour was in the range of 17.5–24.5 g m − 3. The Fast Fourier Transform (FFT) analysis has been performed on these observations to investigate the spectral behaviour of CO2 and water vapour. The relation between CO2 and water vapour on various atmospheric scales has been proposed. CO2 and water vapour observations confirmed the existence of periodicities of large (11, 8 days), meso (5 days) and micrometeorological (20 min) scales.