In this paper we describe a novel lidar that combines differential UV-visible absorption spectroscopy and the lidar technique. The critical and novel element of the system is the use of an imaging spectrometer in conjunction with a two-dimensional CCD detector array to simultaneously spectrally and temporally resolve backscattered radiation. To exploit this approach, the lidar system utilizes a broadband laser output of 10--20 nm full width at half maximum tunable across the UV-visible spectral region, thus allowing the simultaneous measurement of multiple molecular species by the differential optical absorption spectroscopy technique. To demonstrate the flexibility of the technique for tropospheric composition monitoring we present initial results for both elastic and inelastic (Raman) backscatter and for absorption studies in the spectral regions where NO3 and H2O absorb. In addition, the technique has applicability for a wide range of molecules including O3, NO2, and other spectrally structured absorbers and for atmospheric temperature sounding, which may be derived from either rotational Raman return or temperature dependent absorptions such as those of O2. ¿ 1998 American Geophysical Union