Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements

A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present

Influence of Rayleigh-Doppler broadening on the selection of H2O dial system parameters

Computer simulations have enabled the performance of a H2O Differential Absorption Lidar (DIAL) system to be studied by spectrally analyzing the forward propagating and backscattered laser energy. The simulations were done for a high altitude (21 km) DIAL system operating in a nadir-viewing mode. The influence of Rayleigh Doppler broadening on DIAL measurement accuracies were evaluated and show that the Rayleigh broadening influence, which can be corrected to first order in regions free of large aerosol gradients, reduces the sensitivity of DIAL H2O measurement errors in the upper tropospheric region. The ability to correct the Rayleigh broadening and the selection of H2O DIAL parameters when all the systematic effects are combined, were discussed

Theory and operation of the real-time data acquisition system for the NASA-LaRC differential absorption lidar (DIAL)

The improvement of computer hardware and software of the NASA Multipurpose Differential Absorption Lidar (DIAL) system is documented. The NASA DIAL system has undergone development and experimental deployment at NASA/Langley Res. Center for the remote measurement of atmospheric trace gas concentrations from ground and aircraft platforms. A viable DIAL system was developed capable of remotely measuring O3 and H2O concentrations from an aircraft platform. The DIAL Data Acquisition System (DAS) has undergone a number of improvements also. Due to the participation of the DIAL in the Global Tropospheric Experiment, modifications and improvements of the system were tested and used both in the lab and in air. Therefore, this is an operational manual for the DIAL DAS

Clocking connector replaces adapter cables

Single cable using simplified, versatile clocking connector satisfies clocking variations that previously required many cables. Connector consists of specially fabricated grommet follower dial housing, dial assembly, and modified insert

Nd:Glass-Raman laser for water vapor dial

A tunable solid-state Raman shifted laser which was used in a water vapor Differential Absorption Lidar (DIAL) system at 9400 A is described. The DIAL transmitter is based on a tunable glass laser operating at 1.06 microns, a hydrogen Raman cell to shift the radiation to 1.88 microns, and a frequency doubling crystal. The results of measurements which characterize the output of the laser with respect to optimization of optical configuration and of Raman parameters were reported. The DIAL system was also described and preliminary atmospheric returns shown

Differences Between Two Head Start Locations Using the Developmental Indicators for the Assessment of Learning (DIAL) as a Measure of Language and Concepts

The study was conducted on a sample of 43 students between two Head Start locations, A and B. Sociodemographic information was obtained via questionnaires completed by parents at locations A and B. The Developmental Indicators for the Assessment of Learning, Fourth Edition (DIAL-4) was the screener used to assess each child’s performance with regards to language, concept, and motoric development. There was no significant difference between locations A and B for concept and language sub-test standard scores. DIAL motor sub-test scores for locations A and B were statistically significant. This study found that the DIAL is a reliable way to measure concept and language development of preschoolers attending Head Start programs

Comparison of ozone profiles from DIAL, MLS, and chemical transport model simulations over Río Gallegos, Argentina, during the spring Antarctic vortex breakup, 2009

This study evaluates the agreement between ozone profiles derived from the ground-based differential absorption lidar (DIAL), satellite-borne Aura Microwave Limb Sounder (MLS), and 3-D chemical transport model (CTM) simulations such as the Model for Interdisciplinary Research on Climate (MIROC-CTM) over the Atmospheric Observatory of Southern Patagonia (Observatorio Atmosférico de la Patagonia Austral, OAPA; 51.6°S, 69.3°W) in Río Gallegos, Argentina, from September to November 2009. In this austral spring, measurements were performed in the vicinity of the polar vortex and inside it on some occasions; they revealed the variability in the potential vorticity (PV) of measured air masses. Comparisons between DIAL and MLS were performed between 6 and 100hPa with 500km and 24h coincidence criteria. The results show a good agreement between DIAL and MLS with mean differences of ±0.1ppmv (MLS-´DIAL, n,=-) between 6 and 56hPa. MIROC-CTM also agrees with DIAL, with mean differences of ±0.3ppmv (MIROC-CTM-´DIAL, n,=-23) between 10 and 56hPa. Both comparisons provide mean differences of 0.5ppmv (MLS) to 0.8-0.9ppmv (MIROC-CTM) at the 83-100hPa levels. DIAL tends to underestimate ozone values at this lower altitude region. Between 6 and 8hPa, the MIROC-CTM ozone value is 0.4-0.6ppmv (5-8%) smaller than those from DIAL. Applying the scaled PV (sPV) criterion for matching pairs in the DIAL-MLS comparison, the variability in the difference decreases 21-47% between 10 and 56hPa. However, the mean differences are small for all pressure levels, except 6hPa. Because ground measurement sites in the Southern Hemisphere (SH) are very sparse at mid-to high latitudes, i.e., 35-60°S, the OAPA site is important for evaluating the bias and long-Term stability of satellite instruments. The good performance of this DIAL system will be useful for such purposes in the future.Fil: Sugita, Takafumi. National Institute for Environmental Studies; JapónFil: Akiyoshi, Hideharu. National Institute for Environmental Studies; JapónFil: Wolfram, Elian Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Ministerio de Defensa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación en Láseres y Aplicaciones; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Salvador, Jacobo Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Ministerio de Defensa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación en Láseres y Aplicaciones; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentina. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Ohyama, Hirofumi. National Institute for Environmental Studies; Japón. Nagoya University; JapónFil: Mizuno, Akira. Nagoya University; Japó

DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2 lasers

Atmospheric trace constituent measurements with higher vertical resolution than attainable with passive radiometers are discussed. Infrared differential absorption lidar (DIAL), which depends on Mie scattering from aerosols, has special advantages for tropospheric and lower stratospheric applications and has great potential importance for measurements from shuttle and aircraft. Differential absorption lidar data reduction involves comparing large amplitude signals which have small differences. The accuracy of the trace constituent concentration inferred from DIAL measurements depends strongly on the errors in determining the amplitude of the signals. Thus, the commonly used SNR expression (signal divided by noise in the absence of signal) is not adequate to describe DIAL measurement accuracy and must be replaced by an expression which includes the random coherent (speckle) noise within the signal. A comprehensive DIAL computer algorithm is modified to include heterodyne detection and speckle noise. Examples for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system are given

FARMERS AND DERIVATIVES: A SUCCESSFUL COMBINATION IN THE 21ST CENTURY

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