We, a consortium of universities and industries, propose to construct, deploy and manage a unique mobile laboratory facility for the study of the upper ocean and atmosphere. We have named this unique seagoing mobile platform PEARL (Pan-Oceanic Environmental and Atmospheric Research Laboratory) and propose that it be designated a national facility for the study of the ocean and atmosphere by members of the consortium institutions and other interested scientists. We expect that this facility be assembled from components that were largely acquired and/or constructed for other purposes and that are now in storage. In this way we can build the laboratory at a total construction cost that is less than one fourth of the cost that would be necessary were the facility to be constructed from scratch.
The purpose of the PEARL is to increase our understanding of the scattering and attenuation of light in the ocean and atmosphere and to improve our understanding of the dispersal and reaction of anthropogenic and naturally occurring compounds in the earth's atmosphere, to identify the sources and sinks of these materials in both the atmosphere and the upper ocean, and to increase our systematic understanding of the circulation, biology, and mixing within the upper 100 meters of the ocean. We would also expect to provide a real test and evaluation of the integrated optical technologies and identify areas where these technologies need improvement or modification. In addition, we expect to address several key issues in optical oceanography and atmospheric physics that are of keen interest to the U.S. Navy and other branches of the Department of Defense.
Figure 1. Schematics of the PEARL platform indicating some of the research capabilities.
The heart of our proposed effort will be an existing free electron laser light source (FEL) that will be installed and operated from an existing ship (Figure 1). This mobile platform would be able to attack outstanding scientific problems in a number of different environments as diverse as the origin of noctilucent (night luminous) clouds in the polar upper mesosphere (altitude of 80 to 90 km), the concentration of water vapor in the stratosphere, the dispersal of Arctic haze, the development of the Antarctic ozone hole, the sources and dispersion of Los Angeles basin smog, and the effect of volcanic emissions on the albedo and temperature of the earth. Along the track between these remote sites, or as targeted studies in and of themselves, the facility could gather precise information about the bathymetry of coastal regions to a depth of 200 meters, the distribution of phytoplankton and other particulate matter in the upper ocean, the variation of the optical properties of the sea in various environments, the variation of water vapor in the atmosphere as a function of height and lateral position, and perhaps even contribute to the understanding of the recruitment of fish stocks for species of fish currently under substantial fishing pressure.
A FEL aboard a ship promises to be a revolutionary tool for environmental research for it would have the ability to project beams over large expanses of ocean or over basin sized land regions. It would have an immediate application to global change research. The PEARL system's studies of the atmosphere would provide a cost effective source of unambiguous critical data that cannot be obtained by current means. The same unprecedented capabilities could also be applied for other remote sensing applications such as finding manufacturing sites for illicit drugs and weapons of mass destruction, generating nearly real-time maps of the air pollution over large urban areas and establishing the variation in atmospheric moisture content in the vicinity of the land sea interface.
Remote sensing capabilities of the FEL aboard the PEARL are ideally suited for a variety of defense related applications both in peace time as well as in potential conflicts. There is now an increased emphasis on deployment of remote detection and characterization systems for identifying biological and chemical agents of warfare.
The cost of the PEARL will be held down by using an existing ship, FEL hardware contributed by Rockwell International, a surplus aerostat system, etc. The proposed PEARL will have "reach" that will provide many kinds of data that are not accessible with "passive" measurements from satellites and will provide data that unlock the meaning of satellite images.
Considerable effort and expense already have been expended to develop the facilities that are proposed to be incorporated in the PEARL. It is only fitting, therefore, that the agencies that were responsible for the initial development of the individual hardware items should also benefit. Thus we propose that several areas of Navy and DOD relevance also be addressed in the development and deployment of the proposed facility.
For these studies, optical techniques provide mechanisms by which remote sensing over large land and sea masses can be carried out effectively. Recent developments in optical technology present an exceptional opportunity for a substantial improvement in the ability to detect and understand the complex interactions between anthropogenic compounds in the marine and atmospheric environment. It is the goal of this proposal to better understand the attenuation, scattering and fluorescence of light over a wide spectral range (300 nm - 20 Ám) in the upper ocean, marine boundary layer, and the atmosphere. Additional goals are to use the light for probing the vertical structure and spatial and temporal variability of biogenic process in the upper ocean, to better define the anthropogenic loading in the atmosphere and coastal environments, and to provide insights into the reactions that remove these materials from the atmosphere and upper ocean. Concurrent observations of the upper 200 to 500 meters of the ocean will enable studies of bathymetry and natural circulation in coastal regions and in general contribute to the understanding of the distribution of marine life and particulate material in the upper ocean.
Scattering and attenuation of natural and artificial light in the marine boundary layer (MBL) are of concern for both civilian and military operations. Atmospheric attenuation adversely affects laser ranging, free space optical data communications, remote sensing and visibility. The main factors in the atmospheric attenuation are aerosol composition and abundance, Rayleigh scattering, Mie scattering, water vapor content, and temperature inhomogeneity. Often aerosols are the most uncertain factor in modeling optical attenuation in the visible and near infra-red (IR) region. In the upper ocean and coastal areas, the light scattering and attenuation affect underwater visibility, bathymetry, underwater laser communication, mine hunting as well as photosynthesis by phytoplankton - the primary carbon fixing process in the ocean. The variability in the optical properties of the upper ocean are regulated by the amount and quality of particulate and dissolved components resulting from phytoplankton production in the ecosystem. There is a tight coupling between the optical and ecosystem properties of the oceans.
The detailed and simultaneous observation of the vertical structure of the ocean and the atmosphere in real time are not possible with existing instruments, including light detection and ranging (LIDAR) systems because of a combination of constraints imposed by low power and limited wavelength tunability. The proposed PEARL with a powerful tunable laser will enhance our capabilities in marine and atmospheric research.
[C. Helsley, S. Sharma, R. Burke and K. Patel (1996) PEARL: Pan-oceanic Environmental and Atmospheric Research Laboratory; A Consortium Proposal for a National Facility for Marine and Atmospheric Research, pp. 27 (unpublished). S.K. Sharma, C.E. Helsley, R.J. Burke, D.M. Tratt, R.L. Collins, and C.K.N. Patel (1997) Ship-Based Free Electron Laser (FEL) Lidar for Oceanic and Atmospheric Research, in N.K. Saxena (Ed.), Recent Advances in Marine Sciences and Technology, 96 , pp. 191-204, PACON International, Honolulu, HI.]
With no conventional gain medium to overheat, a FEL can be designed for extremely high average power. Based on the existing system, the PEARL's FEL will provide average power of 2 kW in the near infrared, somewhat more in the mid-IR, and somewhat less for operation in the visible and ultraviolet parts of the spectrum. Figure 5 shows an estimated power output spectrum of the FEL as a function of its wavelength. Peak powers in the picosecond-long micro pulses will reach gigawatts, and these will average to megawatts over the microsecond-long macro pulses.
Hawaii Institute of Geophysics and Planetology, SOEST
University of Hawai'i
2525 Correa Road
Honolulu HI 96822
Charles E. Helsley
Sea Grant College Program, SOEST
University of Hawai'i
1000 Pope Road
Honolulu HI 96822
C. Kumar N. Patel
Vice Chancellor (Research)
University of California, Los Angeles
2138 Murphy Hall
Los Angeles CA 90095
Robert J. Burke
114 Limestone Lane
Santa Cruze, CA 95060
phone/fax: (831) 420-1772
Also, for more information about the FEL, please visit the UH Free-Electron Laser Group.
| SOEST Home | HIGP Home |
SOEST WWW systems manager:
This page maintained by:
Brooks Bays and Nancy Hulbirt, at
Last update on Tue 29 June 99