Search Results

You are looking at 1 - 4 of 4 items for

  • Author or Editor: T. P. Tooman x
  • All content x
Clear All Modify Search
D. D. Turner, R. A. Ferrare, L. A. Heilman Brasseur, W. F. Feltz, and T. P. Tooman

Abstract

Automated routines have been developed to derive water vapor mixing ratio, relative humidity, aerosol extinction and backscatter coefficient, and linear depolarization profiles, as well as total precipitable water vapor and aerosol optical thickness, from the operational Raman lidar at the Atmospheric Radiation Measurement (ARM) program's site in north-central Oklahoma. These routines have been devised to maintain the calibration of these data products, which have proven sensitive to the automatic alignment adjustments that are made periodically by the instrument. Since this Raman lidar does not scan, aerosol extinction cannot be directly computed below approximately 800 m due to the incomplete overlap of the outgoing laser beam with the detector's field of view. Therefore, the extinction-to-backscatter ratio at 1 km is used with the aerosol backscatter coefficient profile to compute aerosol extinction from 60 m to the level of complete overlap. Comparisons of aerosol optical depth derived using these algorithms with a collocated CIMEL sun photometer for clear-sky days over an approximate 2-yr period show a slope of 0.90 with a correlation coefficient of 0.884. Furthermore, comparing the aerosol extinction profile retrieved from this system with that from the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center's scanning Raman lidar agrees within 10% for the single available case.

Full access
Anthony Bucholtz, Robert T. Bluth, Ben Kelly, Scott Taylor, Keir Batson, Anthony W. Sarto, Tim P. Tooman, and Robert F. McCoy Jr.

Abstract

Measurements of solar and infrared irradiance by instruments rigidly mounted to an aircraft have historically been plagued by the introduction of offsets and fluctuations into the data that are solely due to the pitch and roll movements of the aircraft. The Stabilized Radiometer Platform (STRAP) was developed to address this problem. Mounted on top of an aircraft and utilizing a self-contained, coupled Inertial Navigation System–GPS, STRAP actively keeps a set of uplooking radiometers horizontally level to within ±0.02° for aircraft pitch and roll angles of up to approximately ±10°. The system update rate of 100 Hz compensates for most pitch and roll changes experienced in normal flight and in turbulence. STRAP was mounted on a Twin Otter aircraft and its performance evaluated during normal flight and during a series of flight maneuvers designed to test the accuracy, range, and robustness of the platform. The measurements from an identical pair of solar pyranometers—one mounted on STRAP and the other rigidly mounted nearby directly to the aircraft—are compared to illustrate the accuracy and capability of the new platform. Results show that STRAP can keep radiometers level within the specified pitch and roll range, that it is able to recover from flight maneuvers outside of this range, and that it greatly increases the quantity of useful radiometer data from any given flight. Of particular note, STRAP now allows accurate measurements of the downwelling solar irradiance during spiral ascents or descents of the aircraft, greatly expanding the utility of aircraft radiometer measurements.

Full access
G. L. Stephens, R. G. Ellingson, J. Vitko Jr., W. Bolton, T. P. Tooman, F. P. J. Valero, P. Minnis, P. Pilewskie, G. S. Phipps, S. Sekelsky, J. R. Carswell, S. D. Miller, A. Benedetti, R. B. McCoy, R. F. McCoy Jr., A. Lederbuhr, and R. Bambha

The U.S. Department of Energy has established an unmanned aerospace vehicle (UAV) measurement program. The purpose of this paper is to describe the evolution of the program since its inception, review the progress of the program, summarize the measurement capabilities developed under the program, illustrate key results from the various UAV campaigns carried out to date, and provide a sense of the future direction of the program. The Atmospheric Radiation Measurement (ARM)–UAV program has demonstrated how measurements from unmanned aircraft platforms operating under the various constraints imposed by different science experiments can contribute to our understanding of cloud and radiative processes. The program was first introduced in 1991 and has evolved in the form of four phases of activity each culminating in one or more flight campaigns. A total of 8 flight campaigns produced over 140 h of science flights using three different UAV platforms. The UAV platforms and their capabilities are described as are the various phases of the program development. Examples of data collected from various campaigns highlight the powerful nature of the observing system developed under the auspices of the ARM–UAV program and confirm the viability of the UAV platform for the kinds of research of interest to ARM and the clouds and radiation community as a whole. The specific examples include applications of the data in the study of radiative transfer through clouds, the evaluation of cloud parameterizations, and the development and evaluation of cloud remote sensing methods. A number of notable and novel achievements of the program are also highlighted.

Full access
J. Verlinde, J. Y. Harrington, G. M. McFarquhar, V. T. Yannuzzi, A. Avramov, S. Greenberg, N. Johnson, G. Zhang, M. R. Poellot, J. H. Mather, D. D. Turner, E. W. Eloranta, B. D. Zak, A. J. Prenni, J. S. Daniel, G. L. Kok, D. C. Tobin, R. Holz, K. Sassen, D. Spangenberg, P. Minnis, T. P. Tooman, M. D. Ivey, S. J. Richardson, C. P. Bahrmann, M. Shupe, P. J. DeMott, A. J. Heymsfield, and R. Schofield

The Mixed-Phase Arctic Cloud Experiment (M-PACE) was conducted from 27 September through 22 October 2004 over the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) on the North Slope of Alaska. The primary objectives were to collect a dataset suitable to study interactions between microphysics, dynamics, and radiative transfer in mixed-phase Arctic clouds, and to develop/evaluate cloud property retrievals from surface-and satellite-based remote sensing instruments. Observations taken during the 1977/98 Surface Heat and Energy Budget of the Arctic (SHEBA) experiment revealed that Arctic clouds frequently consist of one (or more) liquid layers precipitating ice. M-PACE sought to investigate the physical processes of these clouds by utilizing two aircraft (an in situ aircraft to characterize the microphysical properties of the clouds and a remote sensing aircraft to constraint the upwelling radiation) over the ACRF site on the North Slope of Alaska. The measurements successfully documented the microphysical structure of Arctic mixed-phase clouds, with multiple in situ profiles collected in both single- and multilayer clouds over two ground-based remote sensing sites. Liquid was found in clouds with cloud-top temperatures as cold as −30°C, with the coldest cloud-top temperature warmer than −40°C sampled by the aircraft. Remote sensing instruments suggest that ice was present in low concentrations, mostly concentrated in precipitation shafts, although there are indications of light ice precipitation present below the optically thick single-layer clouds. The prevalence of liquid down to these low temperatures potentially could be explained by the relatively low measured ice nuclei concentrations.

Full access