The new Cloud Physics Lidar (CPL) has been built for use on the NASA ER-2 high altitude aircraft.The purpose of the CPL is to provide multi-wavelength measurements of cirrus, subvisual cirrus, and aerosols with high temporal and spatial resolution. The CPL utilizes state-of-the-art technology with a high repetition rate, low pulse energy laser and photon-counting detection. The first deployment for the CPL was the SAFARI-2000 field campaign during AugustSeptember 2000. We provide here an overview of the instrument and initial data results to illustrate the measurement capability of the CPL.

The Cloud‐Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) satellite provides a new and exciting opportunity to study clouds and aerosols in the Earth's atmosphere using range‐resolved laser remote sensing. Following the successful launch of the CALIPSO satellite, validation flights were conducted using the long‐established Cloud Physics Lidar (CPL) to verify CALIPSO's calibration and validate various CALIPSO data products. This paper presents results of the initial comparisons made between the spaceborne CALIPSO lidar and the airborne CPL. Results are presented to validate measurement sensitivity and the spatial properties reported in the CALIPSO data products. Cloud layer top determinations from CALIPSO are found to be in good agreement with those from CPL. Determinations of minimum detectable backscatter are in excellent agreement with theoretical values predicted prior to launch.

Global space borne lidar profiling of atmospheric clouds and aerosol began in 2003 following the launch of the Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud and land Elevation Satellite. GLAS obtains nadir profiles through the atmosphere in two wavelength channels, day and night, at a fundamental resolution of 76.8 m vertical and 172 m along track. The 532 nm channel uses photon‐counting detectors and resolves profiles of observed backscatter cross sections to 10−7 1/m‐sr. The 1064 nm channel employs analog detection adequate to 10−6 1/m‐sr and with greater dynamic range. By 2005 approximately seven months of global data are available. Processing algorithms produce data products for the corrected lidar signal, cloud and aerosol layer boundaries and optical thickness and extinction and backscatter cross sections. Operational sensitivity is shown by the frequency distribution for cloud optical thickness peaking at approximately 0.02.

The Cloud‐Aerosol Transport System (CATS) is an elastic backscatter lidar that was launched on 10 January 2015 to the International Space Station (ISS). CATS provides both space‐based technology demonstrations for future Earth Science missions and operational science measurements. This paper outlines the CATS Level 1 data products and processing algorithms. Initial results and validation data demonstrate the ability to accurately detect optically thin atmospheric layers with 1064 nm nighttime backscatter as low as 5.0E−5 km−1 sr−1. This sensitivity, along with the orbital characteristics of the ISS, enables the use of CATS data for cloud and aerosol climate studies. The near‐real‐time downlinking and processing of CATS data are unprecedented capabilities and provide data that have applications such as forecasting of volcanic plume transport for aviation safety and aerosol vertical structure that will improve air quality health alerts globally.

An improvement to high-spectral-resolution infrared cloud-top altitude retrievals is compared to existing retrieval methods and cloud lidar measurements. The new method, CO2 sorting, determines optimal channel pairs to which the CO2 slicing retrieval will be applied. The new retrieval is applied to aircraft Scanning High-Resolution Interferometer Sounder (S-HIS) measurements. The results are compared to existing passive retrieval methods and coincident Cloud Physics Lidar (CPL) measurements. It is demonstrated that when CO2 sorting is used to select channel pairs for CO2 slicing there is an improvement in the retrieved cloud heights when compared to the CPL for the optically thin clouds (total optical depths less than 1.0). For geometrically thick but tenuous clouds, the infrared retrieved cloud tops underestimated the cloud height, when compared to those of the CPL, by greater than 2.5 km. For these cases the cloud heights retrieved by the S-HIS correlated closely with the level at which the CPL-integrated cloud optical depth was approximately 1.0.