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For the CO2 and CH4 IPDA lidar CHARM-F two single frequency Nd:YAG based MOPA systems were developed. Both lasers are used for OPO/OPA-pumping in order to generate laser radiation at 1645 nm for CH4 detection and 1572 nm for CO2 detection. By the use of a Q-switched, injection seeded and actively length-stabilized oscillator and a one-stage INNOSLAB amplifier about 85 mJ pulse energy could be generated for the CH4 system. For the CO2 system the energy was boosted in second INNOSLAB-stage to about 150 mJ. Both lasers emit laser pulses of about 30 ns pulse duration at a repetition rate of 100 Hz.

Carbon dioxide (CO2) and methane (CH4) are the most important of the greenhouse gases that are directly influenced by human activities. The Integrated Path Differential Absorption (IPDA) lidar technique using hard target reflection in the near IR (1.57μm and 1.64μm) to measure the column-averaged dry air mixing ratio of CO2 and CH4 with high precision and low bias has the potential to deliver measurements from space and air that are needed to understand the sources and sinks of these greenhouse gases. CO2 and CH4 IPDA require tunable laser sources at 1.57 μm and 1.64 μm that coincide with appropriate absorption lines of these species having high pulse energy and average power as well as excellent spectral and spatial properties. Within this study we have realized more than 50mJ of pulse energy in the near IR coincident with appropriate absorption lines using an injection-seeded optical parametric oscillator-amplifier system pumped at 100 Hz. At the same time this device showed excellent spectral and spatial properties. Bandwidths of less than 100 MHz with a high degree of spectral purity (> 99.9 %) have been achieved. The frequency stability was likewise excellent. The M2-factor was better than 2.3. Owing to these outstanding properties optical parametric devices are currently under investigation for the CH4 lidar instrument on the projected French-German climate satellite MERLIN. A similar device is under development at DLR for the lidar demonstrator CHARM-F which will enable the simultaneous measurement of CO2 and CH4 from an airborne platform.

Tropospheric profiles of water vapour and wind were measured with differential absorption lidar (DIAL) and heterodyne detection wind lidar collocated onboard the DLR Falcon research aircraft during the Convective and Orographicallyinduced Precipitation Study (COPS; www.cops2007.de) over Southwest Germany in summer 2007. This international field campaign aimed at refining observational and modelling efforts to improve the forecast skill of convective precipitation over complex terrain in the summer season. The DIAL, a completely new system with four wavelengths (each 50 Hz, 40 mJ) at 935 nm, was installed nadir-viewing. The 2-micron wind lidar was operated either in scanning mode at 20 degrees off-nadir for 3d-wind profiles or in nadir-viewing mode for high resolution vertical wind measurements. The unique combination of both lidars enables the measurement of both horizontal (humidity advection) and vertical (latent heat) fluxes of water vapour that play an eminent role in precipitation forecast and convection initiation. The wind lidar's spatial resolution is 100 m in the vertical and 150 m (vertical wind, boundary layer) to 12 km (3d-wind profiles, whole troposphere) in the horizontal. The DIAL horizontal and vertical resolution ranges from 150 m in the boundary layer to 500 m in the upper troposphere. This high spatial resolution permits the investigation of smallscale processes such as turbulent humidity transport in the convective boundary layer or orographically-induced flow perturbations. Likewise, meso- and synoptic scale processes, e.g. upper level potential vorticity streamers were sampled by flying extended legs across Western Europe.

At the German Aerospace Center an airborne multi-wavelength differential absorption LIDAR for the measurement of atmospheric water vapour is currently under development. This instrument will enable the retrieval of the complete humidity profile from the surface up to the lowermost stratosphere with high vertical and horizontal resolution at a systematic error below 5%. The LIDAR will work in the wavelength region around 935 nm at three different water vapour absorption lines and one reference wavelength. A major sub-system of this instrument is a highly frequency stabilized seed laser system for the optical parametrical oscillators which generate the narrowband high energy light pulses. The development of the seed laser system includes the control software, the electronic control unit and the opto-mechanical layout. The seed lasers are Peltier-cooled distributed feedback laser diodes with bandwidths of about 30 MHz, each one operating for 200 μs before switching to the next one. The required frequency stability is ± 30 MHz ≅ ± 10 -4 nm under the rough environmental conditions aboard an aircraft. It is achieved by locking the laser wavelength to a water vapour absorption line. The paper describes the opto-mechanical layout of the seed laser system, the stabilization procedure and the results obtained with this equipment.

The German Aerospace Establishment (DLR) operates an airborne backscatter lidar based on a Nh:YAG laser which is flashlamp-pumped at 10 Hz. It works on the wavelengths 1064, 532, and 354 nm. It is mounted downward-looking on the research aircraft Falcon 20, flying at about 12 km altitude at speeds of 200 m/s. We present airborne measurements correlated with the orbit tracks of the shuttle-borne LITE-instrument (lidar in-space technology experiment). The emphasis in data evalution is on the comparison between the airborne and the shuttle- borne lidars. First results show excellent agreement between the two instruments even on details of cirrus clouds. The results comprise cloud geometrical and optical depths, as well as profiles of aerosol backscattering coefficients at three wavelengths.