Multistage coupling amplification photoacoustic spectrometry greenhouse gas measurement system and method

The invention discloses a multistage coupling amplification photoacoustic spectrometry greenhouse gas measurement system and method, and belongs to the technical field of trace gas measurement. The measurement system comprises a miniature multi-pass reducing T-shaped photoacoustic cell, a gas distribution system, a DFB laser and a data acquisition and processing system. A reflecting mirror I and a reflecting mirror II are respectively arranged at windows on two sides of the micro multi-pass reducing T-shaped photoacoustic cell; the gas distribution system introduces and fills a gas chamber of the miniature multi-pass variable-diameter T-shaped photoacoustic cell with gas to be detected, the DFB laser generates modulated laser, and the modulated laser enters the miniature multi-pass variable-diameter T-shaped photoacoustic cell from an incidence hole of the reflector I through the collimating lens and is reflected back and forth between the reflectors II, so that a multi-stage coupled and amplified photoacoust