Multi axis differential optical absorption spectroscopy (MAX-DOAS)

[摘要] Multi Axis Differential Optical Absorption Spectroscopy(MAX-DOAS) in the atmosphere is a novel measurement technique that represents a significant advance on the well-established zenithscattered sunlight DOAS instruments which are mainly sensitive to stratospheric absorbers.MAX-DOAS utilizes scattered sunlight received from multiple viewing directions. The spatialdistribution of various trace gases close to the instrument can be derived by combining severalviewing directions. Ground based MAX-DOAS is highly sensitive to absorbers in the lowest fewkilometres of the atmosphere and vertical profile information can be retrieved by combining themeasurements with Radiative Transfer Model (RTM) calculations. The potential of the technique fora wide variety of studies of tropospheric trace species and its (few) limitations are discussed. AMonte Carlo RTM is applied to calculate Airmass Factors (AMF) for the various viewing geometriesof MAX-DOAS. Airmass Factors can be used to quantify the light path length within the absorberlayers. The airmass factor dependencies on the viewing direction and the influence of severalparameters (trace gas profile, ground albedo, aerosol profile and type, solar zenith and azimuthangles) are investigated. In addition we give a brief description of the instrumentalMAX-DOAS systems realised and deployed so far. The results of the RTM studies are compared to severalexamples of recent MAX-DOAS field experiments and an outlook for future possible applications isgiven.

[学科分类] 大气科学