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The high-resolution Doppler lidar (HRDL) was developed to provide higher spatial, temporal, and velocity resolution and more reliable performance than was previously obtainable with CO2-laser-based technology. The improved performance is needed to support continued advancement of boundary layer simulation models and to facilitate high-resolution turbulent flux measurements. HRDL combines a unique, eye-safe, near-IR-wavelength, solid-state laser transmitter with advanced signal processing and a high-speed scanner to achieve 30-m range resolution and a velocity precision of ∼10 cm s−1 under a variety of marine and continental boundary layer conditions, depending on atmospheric and operating conditions. An attitude-compensating scanner has been developed to facilitate shipboard marine boundary layer observations. Vertical velocities, fine details of the wind profile near the surface, turbulence kinetic energy profiles, and momentum flux are measurable with HRDL. The system is also useful for cloud s...

In 1992 the atmospheric lidar remote sensing groups of the National Aeronautics and Space Administration Marshall Space Flight Center, the National Oceanic and Atmospheric Administration/Environmental Technology Laboratory (NOAA/ETL), and the Jet Propulsion Laboratory began a joint collaboration to develop an airborne high-energy Doppler laser radar (lidar) system for atmospheric research and satellite validation and simulation studies. The result is the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS), which has the capability to remotely sense the distribution of wind and absolute aerosol backscatter in three-dimensional volumes in the troposphere and lower stratosphere. A factor critical to the programmatic feasibility and technical success of this collaboration has been the utilization of existing components and expertise that were developed for previous atmospheric research by the respective institutions. For example, the laser transmitter is that of the mobile ground-based Do...

Optical Autocovariance Wind Lidar (OAWL) is a new direct-detection interferometric Doppler lidar approach that inherently enables simultaneous acquisition of multiple-wavelength High Spectral Resolution Lidar calibrated aerosol profiles (OA-HSRL). Unlike other coherent and direct detection Doppler systems, the receiver is self referencing; no specific optical frequency lock is required between the receiver and transmitter. This property facilitates frequency-agile modalities such as DIAL. Because UV laser wavelengths are accommodated, a single transmitter can simultaneously support winds, Raman, fluorescence, DIAL, and HSRL receiver channels, each sampling identical spatial and temporal volumes. LOS species flux measurements are acquired without the usual spatial and temporal sampling errors (or cost, volume, mass, power, and logistical issues) incurred by separate lidar systems, or lidars in combination with other remote or in-situ sensors. A proof of concept (POC) OAWL system has been built and demonstrated at Ball, and OAHSRL POC is in progress. A robust multi-wavelength, field-widened OAWL/OA-HSRL system is under development with planned airborne demonstration from a WB-57 in late 2010. Detailed radiometric and dynamic models have been developed to predict performance in both airborne and space borne scenarios. OA theory, development, demonstration status, advantages, limitations, space and airborne performance, and combined measurement synergies are discussed.

Interferometric testing of large-sized optics in a thermal vacuum environment poses challenges not normally found in an optical metrology lab. Unless the test equipment is thermal-vacuum compatible, it must be installed in an ambient environment with the test item viewed through a window in the thermal-vacuum chamber. Limitations in chamber port size preclude normal-incidence viewing of the full aperture of large-sized optical elements. This necessitates the use of a mechanical translation of the test item to acquire multiple overlying interferograms. The interferograms are then concatenated in order to produce a full-aperture surface map of the test item. This is then used to confirm surface deformation of the entire test mirror. This paper will discuss the challenges, solutions, and results of a series of thermalvacuum tests performed on a large-scale (>40cm) silicon carbide mirror at ambient temperatures.

The Multicenter Airborne Coherent Atmospheric Wind Sensor instrument is an airborne coherent Doppler laser radar (Lidar) capable of measuring atmospheric wind fields and aerosol structure. Since the first demonstration flights onboard the NASA DC-8 research aircraft in September 1995, two additional science flights have been completed. Several system upgrades have also bee implemented. In this paper we discuss the system upgrades and present several case studies which demonstrate the various capabilities of the system.

Since the first remote wind measurements in 1967, coherent Doppler lidar has become established as a unique tool for atmospheric research. Remote sensing of the two-dimensional horizontal wind field with airborne coherent Doppler lidar was demonstrated in 1981 using a low-energy scanning CO2 lidar.1 The scanner and operations control system were subsequently improved to enable wind field measurements at multiple vertical levels, and the system was reflown in 1984.2 Subsequent advances in coherent CO2 laser technology resulted in the development of a frequency-stable, high energy-per-pulse transmitter (~1 J) which was delivered to the National Oceanic and Atmospheric Administration (NOAA) and incorporated into an existing portable ground-based lidar system.3 Thus the possibility arose for the cooperative development of an airborne system with dramatically improved performance, hence greater scientific applications, owing to lower backscatter sensitivity and broader spatial coverage. In 1992 the lidar atmospheric remote sensing groups of the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC), NOAA Environmental Technology Laboratory (ETL), and Jet Propulsion Laboratory (JPL) jointly developed MACAWS, the Multicenter Airborne Coherent Atmospheric Wind Sensor. Existing components were used when possible to minimize programmatic costs. The high-energy laser transmitter is borrowed from the NOAA windvan lidar.3 The ruggedized optical table assembly is borrowed in part from an airborne backscatter lidar developed and flown by JPL. The scanner, telescope and other components are borrowed from a previous airborne Doppler lidar system which was limited in performance primarily to high-backscatter boundary layer features.1,2 Some hardware modifications were required to ensure flight safety, reliability, and compatibility with the aircraft environment.

The first Multi center Airborne Coherent Atmospheric Wind Sensor (MACAWS) field experiment demonstrated an airborne high energy TEA CO2 Doppler lidar system for measurement of atmospheric wind fields and aerosol structure. The system was deployed on the NASA DC-8 during September 1995 in a series of checkout flights to observe several important atmospheric phenomena, including upper level winds in a Pacific hurricane, marine boundary layer winds, cirrus cloud properties, and land-sea breeze structure. The instrument, with its capability to measure 3D winds and backscatter fields, promises to be a valuable tool for climate and global change, severe weather, and air quality research. In this paper, we describe the airborne instrument, assess its performance, discuss future improvements, and show some preliminary results from the September experiments.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A very compact, transportable differential absorption lidar (DIAL) for ozone and aerosol profiling in the lower troposphere (from near surface to about 3 km) has been developed at the National Oceanic and Atmospheric Administration's Environmental Technology Laboratory. The ozone lidar has been employed in two field experiments in California. the first was in intercomparison experiment of the lidar and an airborne ozone analyzer carried out in the Sacramento valley of northern California during July 1993. The second field experiment involving the ozone lidar was the Free Radical Study, carried out in the Los Angeles basin during September 1993, where the highest ozone episode of the year was observed during the experiment. The system will be described and examples of ozone profiles during the high- ozone episode in inland Los Angeles will be shown.

Concurrent measurements of sea-surface retroreflectance and associated wind velocity acquired with an airborne CO2 Doppler lidar are described. These observations provide further insight into thermal infrared optical phenomenology of air-sea interface processes, contribute to a greater understanding of radiation transfer between the atmosphere and the hydrosphere, and enable improved models of wind-driven ocean-surface stress applicable to other remote sensing applications. In particular, we present lidar measurements of azimuthally anisotropic reflectance behavior and discuss the implications to current understanding of sea-surface optical properties.

The atmospheric lidar remote sensing groups of NOAA Environmental Technology Laboratory, NASA Marshall Space Flight Center, and Jet Propulsion Laboratory have developed and flown a scanning, 1 Joule per pulse, CO2 coherent Doppler lidar capable of mapping a three-dimensional volume of atmospheric winds and aerosol backscatter in the planetary boundary layer, free troposphere, and lower stratosphere. Applications include the study of severe and non-severe atmospheric flows, intercomparisons with other sensors, and the simulation of prospective satellite Doppler lidar wind profilers. Examples of wind measurements are given for the marine boundary layer and near the coastline of the western United States.

Published in Petroleum Transactions, AIME, Volume 213, 1958, pages 80–84. Introduction The accumulation of paraffin deposits in tubular goods has been recognized as a major production problem since the inception of the petroleum industry. This problem is not limited to any particular geographical area nor is it limited to a specific type of crude oil. Generally speaking, "paraffin" deposition pertains to the deposition of any predominantly organic material in flow lines, and possibly even at the sand face, which would hamper the production of oil. In some fields, a continuous effort is required to remove deposits of paraffin and in order to accomplish this, many unique methods have been devised. The best solution to this problem, however, is to prevent the formation of such deposits. One method which has been tried in a number of fields is the use of plastic pipe. The purpose of this investigation is to compare the relative effectiveness of several plastic materials to aid in the reduction or prevention of paraffin accumulations in surface flow lines. Composition of Paraffin Deposits By definition, paraffin deposits are those materials which are insoluble in crude oil at the prevailing producing conditions of temperature and pressure. Such deposits usually consist of small particles of petroleum wax intermixed with resins, asphaltic material, and crude oil. They may also contain a variety of foreign materials such as sand, silt, water, various metal oxides, sulfates and carbonates of iron, barium, and calcium. The petroleum waxes deposited in flow strings usually consist of both a "hard" and a "soft" wax fraction. These waxes are largely aliphatic hydrocarbons with smaller amounts of aromatic and naphthenic compounds. Nathan has classified the hard and soft wax fractions. The aliphatic hydrocarbons present are those of high molecular weight with high melting points. Reistle pointed out that these high molecular weight compounds first separate from the oil due to a sharp decrease in solubility as the melting point increases. The identification of the resins and asphaltic materials rests, at present, on an arbitrary solubility procedure. Under certain conditions, materials which are insoluble in pentane (ASTM D–893) are defined as resins and asphalts. Subgrouping of these materials is made on decreasing solubility in benzene and carbon disulfide. Shock found some correlation between the solvent response and the pentane insoluble content of paraffins; higher pentane insoluble fractions are less soluble in any of the commonly used commercial solvents.

Introduction The determination of cloud points has to date been limited to rather transparent oils, visual observation of the formation of a solid phase being the criterion for the standard ASTM D 97-47 method. The need for a quick and simple method for determining cloud points under dynamic conditions for opaque crude oils became necessary in a study of fundamental aspects of paraffin deposition from crude oils. Previous Work The determination of cloud points in opaque oils by viscosity temperature curves is fairly new, Young described a method employing the capillary tube principle. No information exists relative to the determination of cloud points of crude or refined oils under dynamic conditions. Shock noticed that deposition of paraffin from crude oils took place at temperatures at or below the temperature at which a sharp inflection point occurred in the viscosity-temperature curve. This observation indicates a possible correlation between this temperature and the cloud point of the crude oil. Reistle and Vietti have reported that when crude oils containing small amounts of asphaltic materials were heated to temperatures sufficiently high to solubilize these materials and immediately cooled the pour point of the crude oil was lowered as much as 70°F, Sachanen ascribes this effect to the action of colloidal asphaltenes in preventing the formation of the crystalline structure necessary to maintain the oil in a rigid state. At high temperatures, asphaltenes are peptized, and the paraffin crystals formed at these temperatures adsorb the colloidal asphaltenes on their surface thereby hindering further growth of the crystals. Reistle found, however, that such heating and cooling of crude oils had no effect upon the cloud points. This latter work dealt with a crude oil of fixed composition, and the question immediately arises as to the effect of varying the concentration of asphaltic materials on the cloud point.