The Cloud-Aerosol Transport System (CATS) is a multi-wavelength lidar instrument developed to enhance Earth Science remote sensing capabilities from the International Space Station. The CATS project was chartered to be an experiment in all senses: science, technology, and management. As a low-cost project following a strict build-to-cost/ build-to-schedule philosophy, CATS is following a new management approach while also serving as a technology demonstration for future NASA missions. This presentation will highlight the CATS instrument and science objectives with emphasis on how the ISS platform enables the specific objectives of the payload. The development process used for CATS and a look at data being produced by the instrument will also be presented.
Global measurement of tropospheric winds is a key
measurement for understanding atmospheric
dynamics and improving numerical weather
prediction. Global wind profiles remain a high
priority for the operational weather community and
also for a variety of research applications including
studies of the global hydrologic cycle and transport
studies of aerosols and trace species. In addition to
space based winds, high altitude airborne Doppler
lidar systems flown on research aircraft, UAV's or
other advanced sub-orbital platforms would be of
great scientific benefit for studying mesoscale
dynamics and storm systems such as hurricanes. The
Tropospheric Wind Lidar Technology Experiment
(TWiLiTE) is a three year program to advance the
technology readiness level of the key technologies and
subsystems of a molecular direct detection wind lidar
system by validating them, at the system level, in an
integrated airborne lidar system. The TWiLiTE
Doppler lidar system is designed for autonomous
operation on the WB57, a high altitude aircraft
operated by NASA Johnson. The WB57 is capable of
flying well above the mid-latitude tropopause so the
downward looking lidar will measure complete
profiles of the horizontal wind field through the
lower stratosphere and the entire troposphere. The
completed system will have the capability to profile
winds in clear air from the aircraft altitude of 18 km
to the surface with 250 m vertical resolution and < 3
m/s velocity accuracy. Progress in technology
development and status of the instrument design will
Current uncertainties in the role of aerosols and clouds in the Earth's climate system limit our abilities to model the climate system and predict climate change. These limitations are due primarily to difficulties of adequately measuring aerosols and clouds on a global scale. The A-train satellites (Aqua, CALIPSO, CloudSat, PARASOL, and Aura) will provide an unprecedented opportunity to address these uncertainties. The various active and passive sensors of the A-train will use a variety of measurement techniques to provide comprehensive observations of the multi-dimensional properties of clouds and aerosols. However, to fully achieve the potential of this ensemble requires a robust data analysis framework to optimally and efficiently map these individual measurements into a comprehensive set of cloud and aerosol physical properties. In this work we introduce the Multi-Instrument Data Analysis and Synthesis (MIDAS) project, whose goal is to develop a suite of physically sound and computationally efficient algorithms that will combine active and passive remote sensing data in order to produce improved assessments of aerosol and cloud radiative and microphysical properties. These algorithms include (a) the development of an intelligent feature detection algorithm that combines inputs from both active and passive sensors, and (b) identifying recognizable multi-instrument signatures related to aerosol and cloud type derived from clusters of image pixels and the associated vertical profile information. Classification of these signatures will lead to the automated identification of aerosol and cloud types. Testing of these new algorithms is done using currently existing and readily available active and passive measurements from the Cloud Physics Lidar and the MODIS Airborne Simulator, which simulate, respectively, the CALIPSO and MODIS A-train instruments.
An incoherent (direct detection) Doppler lidar is developed that operates in the middle of the visible spectrum and measures wind and aerosol profiles during the day and night from the planetary boundary layer to the lower stratosphere. The primary challenge of making a lidar measurement in the visible spectrum during daylight hours is the strong presence of background light from the sun. To make a measurement of this type, the laser line must be isolated spectrally to the greatest extent possible. This has been accomplished through the use of a multiple étalon Fabry-Pérot interferometer in combination with a narrow-band filter. The incoherent technique and system are a modified version of the Fabry-Pérot interlerometer and image-plane detector technology developed for an earlier Doppler lidar developed at the University of Michigan and for the High-Resolution Doppler Imager (HRDI) now flying on the Upper Atmosphere Research Satellite. The incoherent Doppler analysis is discussed and sample measurements are shown. Winds are measured in the boundary layer with 100-m vertical resolution and 5-mm temporal resolution with 1 to 3 m s-1 accuracy.
The University of Michigan's Space Physics Research Laboratory has constructed a mobile high-spectral-resolution Doppler lidar capable of measuring wind and aerosol loading profiles in the troposphere and lower stratosphere. The system uses a 3-W pulsed frequency-doubled Nd:YAG laser operating at 532 nm as the active source. Backscattered signal is collected by a 44.4-cm-diameter Newtonian telescope. A two axis mirror scanning system allows the instrument to achieve full sky coverage. A pair of Fabry-Perot interferometers in combination with a narrowband (0.1nm) interference filter are used to filter daylight background and provide a high spectral resolving element to measure the Doppler shift. In addition, the aerosol and molecular scattered components of the signal can be separated, giving a measure of the relative aerosol loading. Measurements have been made day and night in the boundary layer with vertical resolution of 100 m and a temporal resolution of approximately 5 minutes. Accuracy of the wind velocity is on the order of 1 to 2 m/s in the boundary layer.
The Southern Oxidants Research Program on Ozone Non-Attainment (SORP-ONA) field study was held in Atlanta, Georgia, during the summer of 1992. SORP-ONA was the first in a series of intensive studies to characterize urban ozone in the South as a part of the Southern Oxidants Study (SOS). The University of Michigan Doppler Lidar was stationed on the Georgia Tech Campus during the study and measured aerosol profiles with approximately 15-minute temporal resolution. A study of mixing in the urban boundary layer determined that aerosol and presumably chemical constituents are not always well-mixed as expected and that some structure does exist. A technique for separation of aerosol and molecular scattered signal for retrieval of aerosol profiles is described. Additionally, a technique is introduced to estimate boundary layer mixing height which shows excellent correlation with rawinsonde potential temperature profile estimates of mixing height.