NARSTO_SOS99NASH_G-1_AIR_CHEMISTRY_DATA is the North American Research Strategy for Tropospheric Ozone (NARSTO) SOS99 Nashville Department of Energy (DOE) G-1 Air Chemistry Data product. Data was collected via the G-1 aircraft deployed during the 1999 campaign to make measurements within the Nashville urban plume. These in situ, semi-Lagrangian measurements, in conjunction with surface-based observations independently made at the Polk Building and at the Cornelia Fort site, allowed quantification of the following:
a) ozone production/loss rates,
b) ozone production efficiency and
c) NOx loss rates within this plume.
Mechanical problems with the G-1 aircraft precluded making additional measurements.

North American Research Strategy for Tropospheric Ozone (NARSTO), which has since disbanded, was a public/private partnership, whose membership spanned across government, utilities, industry, and academe throughout Mexico, the United States, and Canada. The primary mission was to coordinate and enhance policy-relevant scientific research and assessment of tropospheric pollution behavior; activities provide input for science-based decision-making and determination of workable, efficient, and effective strategies for local and regional air-pollution management. Data products from local, regional, and international monitoring and research programs are still available.

M2TCNPLTM (or tavgC_3d_ltm_Np) is a 3-dimensional monthly data collection for climatological long term mean and standard deviation representing the interannual variability on a monthly timescale, derived from monthly Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) datasets. V2 of this data collection is calculated with data from January 1991 to December 2020. In contrast, V1, the original version, is computed with data from an earlier 30-year time of 1981-2010.

This collection consists of meteorological diagnostics at 12 vertical pressure levels (e.g.,850 hPa, 500hPa, and 200 hPa), such as air temperature, wind components, and both relative and specific humidity.

MERRA-2 is the latest version of global atmospheric reanalysis for the satellite era produced by the NASA Global Modeling and Assimilation Office (GMAO) using the Goddard Earth Observing System Model (GEOS) version 5.12.4. The dataset covers the period of 1980-present, with a latency of ~3 weeks after the end of the previous month.

Data Reprocessing: Please check “Records of MERRA-2 Data Reprocessing and Service Changes”, linked from the “Documentation” tab on this page. Note that a reprocessed data filename is different from the original filename.

MERRA-2 Mailing List: Sign up to receive information on reprocessing of data, changes to tools and services, as well as data announcements from GMAO. Contact the GES DISC Help Desk (gsfc-dl-help-disc@mail.nasa.gov) to be added to the list.

Questions: If you have a question, please read the "MERRA-2 File Specification Document'', “MERRA-2 Data Access – Quick Start Guide”, and FAQs linked from the ”Documentation” tab on this page for more information. If these documents do not answer your question, you may email the question on data access to the GES DISC Help Desk (gsfc-dl-help-disc@mail.nasa.gov), or the question on science to the MERRA-2 science team (merra-questions@lists.nasa.gov)

KORUSAQ_Trajectory_Data are FLEXPART backtrajectory products for the DC-8 and Hanseo King Air aircrafts (flight tracks), R/V Onnuri ship tracks and ground stations as part of the KORUS-AQ field campaign. Data collection for this product is complete.

The KORUS-AQ field study was conducted in South Korea during May-June, 2016. The study was jointly sponsored by NASA and Korea’s National Institute of Environmental Research (NIER). The primary objectives were to investigate the factors controlling air quality in Korea (e.g., local emissions, chemical processes, and transboundary transport) and to assess future air quality observing strategies incorporating geostationary satellite observations. To achieve these science objectives, KORUS-AQ adopted a highly coordinated sampling strategy involved surface and airborne measurements including both in-situ and remote sensing instruments.

Surface observations provided details on ground-level air quality conditions while airborne sampling provided an assessment of conditions aloft relevant to satellite observations and necessary to understand the role of emissions, chemistry, and dynamics in determining air quality outcomes. The sampling region covers the South Korean peninsula and surrounding waters with a primary focus on the Seoul Metropolitan Area. Airborne sampling was primarily conducted from near surface to about 8 km with extensive profiling to characterize the vertical distribution of pollutants and their precursors. The airborne observational data were collected from three aircraft platforms: the NASA DC-8, NASA B-200, and Hanseo King Air. Surface measurements were conducted from 16 ground sites and 2 ships: R/V Onnuri and R/V Jang Mok.

The major data products collected from both the ground and air include in-situ measurements of trace gases (e.g., ozone, reactive nitrogen species, carbon monoxide and dioxide, methane, non-methane and oxygenated hydrocarbon species), aerosols (e.g., microphysical and optical properties and chemical composition), active remote sensing of ozone and aerosols, and passive remote sensing of NO2, CH2O, and O3 column densities. These data products support research focused on examining the impact of photochemistry and transport on ozone and aerosols, evaluating emissions inventories, and assessing the potential use of satellite observations in air quality studies.

The Historical Arctic Rawinsonde Archive (HARA) contains millions of vertical soundings of temperature, pressure, humidity, and wind, representing all available rawinsonde ascents from Arctic land stations poleward of 65 degrees North. HARA includes soundings from the beginning of record through mid-1996. Most stations began recording soundings in the late 1950s, but a few began in 1947 or 1948.

This dataset provides a seasonal average climatology of global planetary boundary layer (PBL) height derived from COSMIC/FORMOSAT-3, TerraSAR-X, KOMPSAT-5, and PAZ Global Positioning System (GPS) radio occultation (RO) measurements. The COSMIC/FORMOSAT-3 mission consists of a six-satellite constellation launched in 2006. Each satellite carries an Integrated GPS Occultation Receiver (IGOR) GPS receiver and is equipped with fore and aft looking antenna to track both setting and rising occultations. The constellation provides globally distributed measurements across different local times. The instrument tracks the L-band microwave signal broadcast by a GPS satellite in a limb-viewing geometry. The IGOR receivers are capable of tracking the GPS signals in open loop through the middle to lower troposphere, which is essential for obtaining data with high quality for PBL height estimation, especially at low latitudes. The refractivity profiles form the basis for this PBL height product. For each occultation, the PBL height is calculated as the height where the vertical gradient of the refractivity (dN/dz) is minimum. This algorithm is designed to locate the height where a large vertical change in refractivity occurs, corresponding to the transition from the free troposphere to the PBL. More details can be found in Ao et al. (2012). This is the latest version of this collection which supersedes previous versions.

This dataset provides an annual average climatology of planetary boundary layer (PBL) height derived from COSMIC/FORMOSAT-3, TerraSAR-X, KOMPSAT-5, and PAZ Global Positioning System (GPS) radio occultation (RO) measurements. The COSMIC/FORMOSAT-3 mission consists of a six-satellite constellation launched in 2006. Each satellite carries an Integrated GPS Occultation Receiver (IGOR) GPS receiver and is equipped with fore and aft looking antenna to track both setting and rising occultations. The constellation provides globally distributed measurements across different local times. The instrument tracks the L-band microwave signal broadcast by a GPS satellite in a limb-viewing geometry. The IGOR receivers are capable of tracking the GPS signals in open loop through the middle to lower troposphere, which is essential for obtaining data with high quality for PBL height estimation, especially at low latitudes. The refractivity profiles form the basis for this PBL height product. For each occultation, the PBL height is calculated as the height where the vertical gradient of the refractivity (dN/dz) is minimum. This algorithm is designed to locate the height where a large vertical change in refractivity occurs, corresponding to the transition from the free troposphere to the PBL. More details can be found in Ao et al. (2012). This is the latest version of this collection which supercedes previous versions.

FIREXAQ_N46_Data are the wind profile and fire temperature data collected onboard the NOAA-MET Twin Otter during FIREX-AQ. This product includes data collected by the Nighttime Fire Observations eXperiment (NightFOX) UAS and wind lidar. Data collection for this product is complete. This data was collected by the NOAA Chemical Sciences Laboratory (CSL).

Completed during summer 2019, FIREX-AQ utilized a combination of instrumented airplanes, satellites, and ground-based instrumentation. Detailed fire plume sampling was carried out by the NASA DC-8 aircraft, which had a comprehensive instrument payload capable of measuring over 200 trace gas species, as well as aerosol microphysical, optical, and chemical properties. The DC-8 aircraft completed 23 science flights, including 15 flights from Boise, Idaho and 8 flights from Salina, Kansas. NASA’s ER-2 completed 11 flights, partially in support of the FIREX-AQ effort. The ER-2 payload was made up of 8 satellite analog instruments and provided critical fire information, including fire temperature, fire plume heights, and vegetation/soil albedo information. NOAA provided the NOAA-CHEM Twin Otter and the NOAA-MET Twin Otter aircraft to measure chemical processing in the lofted plumes of Western wildfires. The NOAA-CHEM Twin Otter focused on nighttime plume chemistry, from which data is archived at the NASA Atmospheric Science Data Center (ASDC). The NOAA-MET Twin Otter collected measurements of air movements at fire boundaries with the goal of understanding the local weather impacts of fires and the movement patterns of fires. Additionally, a ground-based station in McCall, Idaho and several mobile laboratories provided in-situ measurements of aerosol microphysical and optical properties, aerosol chemical compositions, and trace gas species.

The Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) campaign was a NOAA/NASA interagency intensive study of North American fires to gain an understanding on the integrated impact of the fire emissions on the tropospheric chemistry and composition and to assess the satellite’s capability for detecting fires and estimating fire emissions. The overarching goal of FIREX-AQ was to provide measurements of trace gas and aerosol emissions for wildfires and prescribed fires in great detail, relate them to fuel and fire conditions at the point of emission, characterize the conditions relating to plume rise, and follow plumes downwind to understand chemical transformation and air quality impacts.

DISCOVERAQ_Texas_MetNav_AircraftInSitu_UC12_Data contains in situ meteorological and navigational data collected onboard NASA's UC-12 aircraft during the Texas (Houston) deployment of NASA's DISCOVER-AQ field study. This product contains the UC-12 navigational data collected via the APPLANIX. This data product contains data for only the Texas deployment and data collection is complete.

Understanding the factors that contribute to near surface pollution is difficult using only satellite-based observations. The incorporation of surface-level measurements from aircraft and ground-based platforms provides the crucial information necessary to validate and expand upon the use of satellites in understanding near surface pollution. Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) was a four-year campaign conducted in collaboration between NASA Langley Research Center, NASA Goddard Space Flight Center, NASA Ames Research Center, and multiple universities to improve the use of satellites to monitor air quality for public health and environmental benefit. Through targeted airborne and ground-based observations, DISCOVER-AQ enabled more effective use of current and future satellites to diagnose ground level conditions influencing air quality.

DISCOVER-AQ employed two NASA aircraft, the P-3B and King Air, with the P-3B completing in-situ spiral profiling of the atmosphere (aerosol properties, meteorological variables, and trace gas species). The King Air conducted both passive and active remote sensing of the atmospheric column extending below the aircraft to the surface. Data from an existing network of surface air quality monitors, AERONET sun photometers, Pandora UV/vis spectrometers and model simulations were also collected. Further, DISCOVER-AQ employed many surface monitoring sites, with measurements being made on the ground, in conjunction with the aircraft. The B200 and P-3B conducted flights in Baltimore-Washington, D.C. in 2011, Houston, TX in 2013, San Joaquin Valley, CA in 2013, and Denver, CO in 2014. These regions were targeted due to being in violation of the National Ambient Air Quality Standards (NAAQS).

DISCOVERAQ_Maryland_MetNav_AircraftInSitu_UC12_Data contains in situ meteorological and navigational data collected onboard NASA's UC-12 aircraft during the Maryland (Baltimore-Washington) deployment of NASA's DISCOVER-AQ field study. This product contains the UC-12 navigational data collected via the APPLANIX. This data product contains data for only the Maryland deployment and data collection is complete.

Understanding the factors that contribute to near surface pollution is difficult using only satellite-based observations. The incorporation of surface-level measurements from aircraft and ground-based platforms provides the crucial information necessary to validate and expand upon the use of satellites in understanding near surface pollution. Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) was a four-year campaign conducted in collaboration between NASA Langley Research Center, NASA Goddard Space Flight Center, NASA Ames Research Center, and multiple universities to improve the use of satellites to monitor air quality for public health and environmental benefit. Through targeted airborne and ground-based observations, DISCOVER-AQ enabled more effective use of current and future satellites to diagnose ground level conditions influencing air quality.

DISCOVER-AQ employed two NASA aircraft, the P-3B and King Air, with the P-3B completing in-situ spiral profiling of the atmosphere (aerosol properties, meteorological variables, and trace gas species). The King Air conducted both passive and active remote sensing of the atmospheric column extending below the aircraft to the surface. Data from an existing network of surface air quality monitors, AERONET sun photometers, Pandora UV/vis spectrometers and model simulations were also collected. Further, DISCOVER-AQ employed many surface monitoring sites, with measurements being made on the ground, in conjunction with the aircraft. The B200 and P-3B conducted flights in Baltimore-Washington, D.C. in 2011, Houston, TX in 2013, San Joaquin Valley, CA in 2013, and Denver, CO in 2014. These regions were targeted due to being in violation of the National Ambient Air Quality Standards (NAAQS).

DISCOVERAQ_Colorado_Ground_Platteville_Data contains data collected at the Platteville ground site during the Colorado (Denver) deployment of NASA's DISCOVER-AQ field study. This data product contains data for only the Colorado deployment and data collection is complete.

Understanding the factors that contribute to near surface pollution is difficult using only satellite-based observations. The incorporation of surface-level measurements from aircraft and ground-based platforms provides the crucial information necessary to validate and expand upon the use of satellites in understanding near surface pollution. Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) was a four-year campaign conducted in collaboration between NASA Langley Research Center, NASA Goddard Space Flight Center, NASA Ames Research Center, and multiple universities to improve the use of satellites to monitor air quality for public health and environmental benefit. Through targeted airborne and ground-based observations, DISCOVER-AQ enabled more effective use of current and future satellites to diagnose ground level conditions influencing air quality.

DISCOVER-AQ employed two NASA aircraft, the P-3B and King Air, with the P-3B completing in-situ spiral profiling of the atmosphere (aerosol properties, meteorological variables, and trace gas species). The King Air conducted both passive and active remote sensing of the atmospheric column extending below the aircraft to the surface. Data from an existing network of surface air quality monitors, AERONET sun photometers, Pandora UV/vis spectrometers and model simulations were also collected. Further, DISCOVER-AQ employed many surface monitoring sites, with measurements being made on the ground, in conjunction with the aircraft. The B200 and P-3B conducted flights in Baltimore-Washington, D.C. in 2011, Houston, TX in 2013, San Joaquin Valley, CA in 2013, and Denver, CO in 2014. These regions were targeted due to being in violation of the National Ambient Air Quality Standards (NAAQS).

The first objective of DISCOVER-AQ was to determine and investigate correlations between surface measurements and satellite column observations for the trace gases ozone (O3), nitrogen dioxide (NO2), and formaldehyde (CH2O) to understand how satellite column observations can diagnose surface conditions. DISCOVER-AQ also had the objective of using surface-level measurements to understand how satellites measure diurnal variability and to understand what factors control diurnal variability. Lastly, DISCOVER-AQ aimed to explore horizontal scales of variability, such as regions with steep gradients and urban plumes.