Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) was a NASA-led campaign that studied air quality using remote sensing techniques, to improve air quality forecasts. DISCOVER-AQ had 4 deployments that took place from 2011 to 2014 across different portions of the contiguous United States. Each deployment used a variety of aircraft including NASA’s P-3 and B-200, as well as ground instrumentation to compare surface observations with column observations of aerosols and trace gases. Aircraft and ground instrument measurements were also supplemented with satellite and model observations to help improve air quality estimates in regions of steep gradients. DISCOVER-AQ was one of NASA’s Earth Venture Suborbital-1 projects.
2011-06-27 — 2014-08-16
Baltimore MD, San Joaquin Valley CA, Houston TX, Denver CO
The Airborne Compact Atmospheric Mapper (ACAM) is a remote-sensing airborne spectrometer designed at NASA's Goddard Space Flight Center (GSFC). It utilizes two thermally stabilized spectrometers to collect measurements of nitrogen dioxide, sulfur dioxide, ozone, formaldehyde, and aerosols in the ultraviolet, visible, and near-infrared spectral range (310-900 nm). ACAM typically operates at a spatial resolution of 30 m and a temporal resolution of 10 Hz. Measurements from ACAM can be used for calibration and validation of observations from the Aura satellite.
The Second Generation High Spectral Resolution Lidar (HSRL-2) is an airborne lidar developed by the NASA Langley Research Center. HSRL-2 measures aerosol backscatter at the 355, 532, and 1064 nm wavelengths and aerosol extinction at the 355 and 532 nm wavelengths. It has a horizontal resolution of 1-2 km and a vertical resolution of 15 m, and it takes measurements roughly every 0.5 seconds. It replaced the High Spectral Resolution Lidar (HSRL).
The Pandora Spectrometer System is a ground-based UV-VIS spectrometer used to measure column amounts of trace gases in the atmosphere. It uses total optical absorption spectroscopy for retrievals of ozone, nitrogen dioxide, formaldehyde, and other trace gases. Pandora operates in the 280-525 nm spectral region at a resolution of 0.6 nm. It can make both direct sun and all-sky radiance measurements and has an overall measurement time of 80 seconds. Pandora is a part of a network of identical instruments known as the Pandonia Global Network.
The NASA Micro-Pulse Lidar Network (MPLNET) is a global ground-based network of Micro-Pulse Lidar (MPL) systems that has been active since 1999. MPLNET provides continuous measurements of aerosol and cloud vertical structure as well as boundary layer height from the surface up to 30 km. The MPL systems operate at a wavelength range of 523-532 nm and have a vertically-resolved spatial resolution of 30 to 75 m depending on the station. Many of the MPLNET sites are co-located with sites in the NASA Aerosol Robotic Network (AERONET) to help reduce errors in retrievals.
The AErosol RObotic NETwork (AERONET) is a federated network of ground-based remote sensing aerosol sensors established by NASA and the PHOtométrie pour le Traitement Opérationnel de Normalisation Satellitaire (PHOTONS) in 1993. Each AERONET site consists of a CIMEL Electronique sunphotometer that provides measurements of sun irradiance and sky radiances. These measurements can be used to retrieve aerosol properties such as aerosol optical depth and extinction. The sunphotometers operate across nine wavelengths (340, 380, 440, 500, 675, 870, 937, 1020, and 1640 nm) and provide aerosol measurements approximately every 15 min. AERONET sites are located across the world, making it possible to map around 90% of the Earth’s surface.
The Nittany Atmospheric Trailer & Integrated Validation Experiment (NATIVE) is a mobile research facility used for satellite validation, air quality monitoring, and pollution transport and deposition. The NATIVE payload includes in situ trace instruments, passive and active remote sensing instruments, and several meteorological probes. It is owned and operated by Pennsylvania State University.
The Atmospheric Vertical Observations of CO2 in the Earth’s Troposphere (AVOCET) is an airborne in situ spectrometer developed by NASA’s Langley Research Center (LaRC). AVOCET uses a differential, non-dispersive infrared spectrometer to provide high-resolution measurements of carbon dioxide (CO2). It operates at the 4.26 μm CO2 absorption band and has a measurement frequency of 5 Hz. AVOCET has been deployed in several field investigations since the early 1990s and has participated in over 450 science flights.
Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentration. CPCs measure aerosol concentration by condensing fluid onto the particles, allowing them to grow to more detectable sizes for optical scattering. Typically, CPCs can detect particles with a size range of 7 nm-3 μm, can measure particle concentrations up to 100,000 particles/cc, and can provide measurements at 1-second intervals. CPCs are manufactured by TSI Incorporated and can be deployed on airborne, shipborne, and ground-based platforms.
The Difference Frequency Generation Absorption Spectrometer is an instrument designed to measure formaldehyde in the atmosphere. It measures the gas using an infrared laser. The instrument uses two lasers that operate at 1562nm and 1083nm. The instrument was used in multiple campaigns, and has since been replaced by the Compact Atmospheric Multispecies Spectrometer (CAMS).
The Thermal-Dissociation Laser Induced Fluorescence (TD-LIF) is an in situ airborne sensor developed at UC Berkeley. It uses a combination of the TD and LIF techniques to measure nitrogen dioxide (NO2), peroxynitrates, nitric acid (HNO3), and other stable organic nitrates in the atmosphere. TD-LIF operates at the 585 nm wavelength and has a typical measurement frequency of 1 Hz.
The Scanning Mobility Particle Sizer (SMPS) is an in situ airborne or ground-based aerosol sensor manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles to determine the size distribution. It also measures the number of aerosol particles by using a condensation particle counter (CNC). It can detect particles within the size range of 10-1000 nm and can provide measurements typically around 10 seconds per scan.
Earth Science > Atmosphere > Aerosols
Earth Science > Atmosphere > Aerosols > Chemical Composition
The Proton Transfer Mass Spectrometer (PTR-MS) is an in situ airborne and ground-based spectrometer designed by the University of Innsbruck in Austria. It measures volatile organic compounds (VOCs) without sample preparation at very low concentrations. PTR-MS uses chemical ionization mass spectroscopy allowing for fast and highly sensitive detection of VOCs. It has a 0.5 to 1 s signal integration time.
The Optical Particle Counter is an instrument based on the principle of light scattering from particles. It is a real time instrument that is typically used to measure particles above 0.05 μm in diameter.
The Differential Absorption Carbon monOxide Measurements (DACOM) is an airborne in situ spectrometer system. It uses the differential absorption technique and an infrared tunable diode laser (TDL) to collect measurements of nitrous oxide (N2O), carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) in the atmosphere. DACOM operates across the 4.7, 4.5, and 3.3 μm wavelengths to access the absorption lines for CO, N2O, and CH4. It has a measurement frequency of 5 Hz and a precision of about 1 ppbv.
The Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) is an in situ spectrometer manufactured by Droplet Measurement Technologies. It can be utilized on both airborne and ground-based platforms to measure aerosol size distribution and concentration. UHSAS determines the particle size by detecting the peak light signals of the aerosol particles which are illuminated by a 1054 nm laser. UHSAS can sample particles within the 60 - 1000 nm size range and has a sampling frequency of 10 Hz.
The Diode Laser Hygrometer (DLH) is an in situ airborne hygrometer developed by NASA’s Langley Research Center (LaRC). It uses tunable diode laser absorption to measure water vapor in the atmosphere. DLH operates in the near-infrared region at around 1.4 μm and has a measurement frequency of 100 Hz. It can provide accurate measurements of water vapor even while flying through clouds.
Earth Science > Atmosphere > Atmospheric Water Vapor
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Water Vapor
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Humidity > Relative Humidity
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Humidity
The Langley Aerosol Research Group Experiment (LARGE) is an in situ airborne instrument suite that measures aerosol and cloud microphysical and optical properties such as size distribution, number concentration, and scattering and absorption coefficient. LARGE consists of multiple instruments including the Ultra-High Sensitivity Aerosol Spectrometer (UHSAS), Particle-Into-Liquid Sampler (PILS), Particle Soot Absorption Photometer (PSAP), Cloud and Aerosol Spectrometer (CAS), Cloud Imaging Probe (CIP), and additional cloud and aerosol sensors. The LARGE instruments operate across the 450-700 nm wavelength range, can detect particles in the size range between 0.003-20μm, and have a measurement frequency of 1 Hz. It is typically used for airborne measurements, but it also can be deployed on ground-based platforms such as vehicles.
NOx/NOxy is an in situ chemiluminescence instrument. It provides measurements of nitrogen oxides and ozone in the atmosphere at a spatial resolution better than 100m for typical DC-8 research flight speeds. NOx/NOxy can be utilized on ground-based, airborne, and shipborne platforms allowing it to be used in various types of atmospheric chemistry and air quality studies.
Earth Science > Atmosphere > Air Quality > Nitrogen Oxides
Nephelometers are in situ airborne or ground-based optical sensors. They measure the total scattering and backscattering of aerosol particles in the atmosphere. Nephelometers operate across three wavelengths: 450 nm, 550 nm, and 700 nm, and have a typical time resolution of 1 Hz.
The Langley Mobile Ozone Lidar (LMOL) is an active remote sensor that utilizes a laser to measure atmospheric ozone and aerosols. LMOL is housed in a trailer so that it is easily transferred to different locations. The laser has a 287 nm and a 292 nm wavelength for ozone retrievals and a 527 nm wavelength for other aerosol retrievals. In addition, it has a 70 ns pulse width and a 7.5 m range resolution. LMOL is part of the Tropospheric Ozone Lidar Network (TOLNet), which is operated by NASA.
Earth Science > Atmosphere > Air Quality > Tropospheric Ozone
The NASA Goddard Tropospheric Ozone Lidar (TROPOZ) is a mobile, ground-based lidar that is part of the Tropospheric Ozone Lidar Network (TOLNet). It uses the differential absorption lidar (DIAL) technique to measure ozone at 289 nm and 299 nm. TROPOZ has a range resolution of 15 m, a repetition rate of 50 Hz, and can generate ozone profiles from 0.35 to 16 km above ground level.
Earth Science > Atmosphere > Air Quality > Tropospheric Ozone
The Nittany Atmospheric Trailer & Integrated Validation Experiment (NATIVE) is a mobile research facility used for satellite validation, air quality monitoring, and pollution transport and deposition. The NATIVE payload includes in situ trace instruments, passive and active remote sensing instruments, and several meteorological probes. It is owned and operated by Pennsylvania State University.
The Tropospheric Ozone Lidar Network (TOLNet) is an interagency initiative among NASA, NOAA, and USEPA starting in 2011. TOLNet provides highly time-resolved measurements of tropospheric ozone profiles that support air quality research and satellite validation. TOLNet consists of six different sensors across the United States: Jet Propulsion Laboratory’s Table Mountain tropospheric Ozone DIfferential Absorption Lidar (JPL-TMO DIAL), NOAA’s Earth System Research Laboratory Tunable Optical Profiler for Aerosol and oZone (TOPAZ), University of Alabama in Huntsville’s Rocket-city Ozone Quality Evaluation in the Troposphere (RO3QET), Goddard Space Flight Center’s TROPospheric OZone-DIfferential Absorption Lidar (TROPOZ DIAL), Langley Research Center’s Langley Mobile Ozone Lidar (LMOL), and Environment and Climate Change Canada’s Autonomous Mobile Ozone LIDAR Instrument for Tropospheric Experiments (AMOLITE). The mobile systems within TOLNet can be deployed in the field to provide collocated measurements of ozone with balloon and airborne sensors.
Earth Science > Atmosphere > Air Quality > Tropospheric Ozone
