J. Riccobono - Academia.edu (original) (raw)

Papers by J. Riccobono

Journal of geophysical research. Space physics, Jun 29, 2024

The datasets are observations of thermospheric neutral winds and temperatures recorded by a Fabry... more The datasets are observations of thermospheric neutral winds and temperatures recorded by a Fabry-Perot interferometer. These data can be used to study the dynamics of the low-latitude ionosphere in Brazil. The data were organized by Dr. Jonas R. Souza (jonas.souza@inpe.br) from the National Institute for Space Research - INPE.

Journal of Geophysical Research: Space Physics

The spectral line profile of the atomic oxygen O1D2—3P2 transition near 6300 Å in the airglow has... more The spectral line profile of the atomic oxygen O1D2—3P2 transition near 6300 Å in the airglow has been used for more than 50 years to extract neutral wind and temperature information from the F‐region ionosphere. A new spectral model and recent samples of this airglow emission in the presence of the nearby lambda‐doubled OH Meinel (9‐3) P2(2.5) emission lines underscores earlier cautions that OH can significantly distort the OI line center position and line width observed using a single‐etalon Fabry‐Perot interferometer (FPI). The consequence of these profile distortions in terms of the emission profile line width and Doppler position is a strong function of the selected etalon plate spacing. Single‐etalon Fabry‐Perot interferometers placed in the field for thermospheric measurements have widely varying etalon spacings, so that systematic wind biases caused by the OH line positions differ between instruments, complicating comparisons between sites. Based on the best current determin...

AGU Fall Meeting Abstracts, Dec 1, 2012

AGU Fall Meeting Abstracts, Dec 1, 2019

Journal of Geophysical Research: Space Physics, 2014

The first midlatitude conjugate thermospheric wind observations in the American sector showed var... more The first midlatitude conjugate thermospheric wind observations in the American sector showed various degrees of conjugacy between Palmer (64°S, 64°W, magnetic latitude (MLAT) 50°S) and Millstone Hill (42.82°N, 71.5°W, MLAT 53°N) under three different geomagnetic conditions (recovery after a substorm, moderately active, and quiet). The agreement with the National Center for Atmospheric Research's Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulations also varies with the geomagnetic activity level. During substorm recovery, the observations at Palmer (PA) and Millstone Hill (MH) both showed strong westward zonal winds, which the standard TIEGCM greatly underestimated. Inadequate ion convection pattern size and lack of effect from Subauroral Polarization Streams (SAPS) may be the cause of the large discrepancy. The TIEGCM with a SAPS model produced stronger westward zonal winds near PA but did not change the zonal wind near MH. The empirical SAPS model needs further refinements. In general, there is better conjugacy with moderate geomagnetic activity levels. The TIEGCM also agrees better with the observations. Under geomagnetically quiet conditions, the meridional winds appear to be less conjugate. The agreement between the observations and model is reasonable. Optical conjugate observations are severely limited by the seasons and weather conditions in the two hemispheres. Yet they are necessary to understanding the thermospheric dynamics in the subauroral region and its relationship with geomagnetic activity levels. The comparisons with TIEGCM are necessary for future model improvements. In the past, there have been climatological studies of the thermospheric winds at MH and Halley Bay (HB), Antarctica (76°S, 27°W, MLAT 63°) by Emmert et al. [2006, 2008] during geomagnetically quiet and active periods. Since MH and HB are not close to conjugate and studies were based on statistical analysis, how the WU ET AL.

Imaging Spectrometry XIV, 2009

An imager based upon an etched liquid-crystal Fabry-Perot (LCFP) dispersive element is able to si... more An imager based upon an etched liquid-crystal Fabry-Perot (LCFP) dispersive element is able to simultaneously sample four distinct resolution elements in the region 800 nm - 1100 nm, and tune in milliseconds to any one of 30,661 possible four-color scene images with a spectral resolution of 0.67 nm. Independently tunable quadrants of a single LCFP etalon are created by etching

Advances in Space Research, 2013

Multispectral imaging of optical emissions in the Earth's upper atmosphere unravels vital informa... more Multispectral imaging of optical emissions in the Earth's upper atmosphere unravels vital information about dynamic phenomena in the Earth-space environment. Wavelength tunable filters allow us to accomplish this without using filter wheels or multiple imaging setups, but with identifiable caveats and trade-offs. We evaluate one such filter, a liquid crystal Fabry-Perot etalon, as a potential candidate for the next generation of imagers for aeronomy. The tunability of such a filter can be exploited in imaging features such as the 6300-6364 Å oxygen emission doublet, or studying the rotational temperature of N þ 2 in the 4200-4300 Å range, observations which typically require multiple instruments. We further discuss the use of this filter in an optical instrument, called the Liquid Crystal Hyperspectral Imager (LiCHI), which will be developed to make simultaneous measurements in various wavelength ranges.

Hyperspectral imaging refers to the measurement of data in a number of contiguous wavelengths. It... more Hyperspectral imaging refers to the measurement of data in a number of contiguous wavelengths. It has increasingly been used in remote sensing to obtain information about a scene in many applications ranging from vegetation analysis to aeronomy. The information obtained from optical methods can be spatial, temporal, spectral, polarimetric or a combination of these. An ideal and versatile instrument is one which can provide information in all four domains at high spectral resolution, and can be used for many applications with minimum modifications. In this work we present our first attempt at building such a hyperspectral imaging system called Liquid Crystal Hyperspectral Imager (LiCHI) which uses Liquid Crystal Fabry-Perot etalons. LiCHI has been built and tested for three applications, viz. auroral imaging, outlier detection and environmental or vegetation analysis. Preliminary measurements and analyses from these tests are presente...

Optical Engineering, 1997

A novel device, the nonspatial filter, is described for laser beam cleanup. It is based on the Br... more A novel device, the nonspatial filter, is described for laser beam cleanup. It is based on the Bragg selectivity of thick holograms. Unlike pinhole and fiber spatial filters, which employ lenses and apertures in the transform plane, nonspatial filters operate directly on the laser beam. This eliminates the need for laser beam focusing, which is the source of many of the material and alignment instabilities and laser power limitations of spatial filters. Standard holographic materials are not suitable for this application because differential shrinkage during processing limits the maximum Bragg angle selectivity attainable, and because they are generally too thin. New technologies that eliminate the problem of differential shrinkage are described. These technologies are based either on the use of a rigid porous substrate material, such as porous glass, filled with a light-sensitive material, such as holographic photopolymers or dichromated gelatin, or on the use of a thick photopolymer with diffusion amplification (PDA). We report results of holographic nonspatial filtering of a laser beam in one dimension, with an angular selectivity of better than 1 mrad.

This work presents the results for the 7320A line width data acquired from April to October of 20... more This work presents the results for the 7320A line width data acquired from April to October of 2008 at Arecibo (18.35N, 66.75W) using a CCD array detection with a high-spectral resolution Fabry-Perot interferometer. The excited O+(2P) atom is formed by photoionization or electron impact with energy in excess of 18.6EV (&amp;amp;amp;amp;amp;amp;amp;lt; 666Å). With a lifetime of 4.57s in the upper

Results from recently upgraded optical interferometer systems installed at the Arecibo Observator... more Results from recently upgraded optical interferometer systems installed at the Arecibo Observatory in Arecibo, Puerto Rico are presented. These instruments autonomously and simultaneously observe optical emissions from thermospheric oxygen at two different altitudes. These new dichroic instruments, which combine a telecentric imaging system with large aperture interferometers, have resulted in a dramatic increase in instrument sensitivity and data collection cadence. The instrument control system is modernized for fully robotic operation utilizing a client-server model. Thermospheric winds and temperatures are collected every clear night of every month, with wavelength calibration, camera diagnostics (bias, dark, and flatfield calibrations), and data-taking control available from any internet connection. Neutral, meridional and zonal wind vectors typically have 1 m/s statistical errors, and neutral temperatures have statistical errors <15K in three minute exposures. Operation and...

Optical …, 1997

Results from recently upgraded Fabry Perot interferometer systems installed at the Millstone Hill... more Results from recently upgraded Fabry Perot interferometer systems installed at the Millstone Hill observatory in Westford Massachusetts are presented. These instruments autonomously observe the 630.0 nm emission from thermospheric O1D and the O1S 557.7 nm emission from lower thermospheric Oxygen. The older single pixel detection system was replaced with a low noise CCD camera, and the order-sorting interference filter is located in a telecentric position, The instrument control system is modernized for fully remote or automated control through internet communication. Thermospheric winds and temperatures are collected every clear night of any month, with wavelength calibration, camera diagnostics (bias, dark, and flat-field calibrations), and data taking control available from any internet connection. Neutral meridional and zonal wind vectors typically have 1 m/s errors and neutral temperatures have statistical errors <15K in four minute exposures . Operation and analysis algorith...

Proceedings of SPIE - The International Society for Optical Engineering

F-region night-time neutral winds at Millstone Hill Observatory have been studied using a Fabry-P... more F-region night-time neutral winds at Millstone Hill Observatory have been studied using a Fabry-Perot Interferometer (FPI) from a nine month period between April, 2010 to December 2010. This paper discusses monthly variations in these night-time thermospheric winds near 250 km during periods of geomagnetically quiet times (Kp < 3). A detailed comparison is made between the FPI neutral winds and predictions from the NCAR Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIMEGCM). During the April-September period, the observed wind circulation pattern shows flows that are poleward and westward in the morning sector, equatorward near the local mid-night, and poleward and eastward in the evening sector. Thermospheric wind circulation during the October-December period is poleward during the evening and morning sectors and equator near the local midnight. The TIMEGCM thermospheric wind predictions at Millstone Hill are in good agreement with the FPI observ...