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The Tropospheric Emissions: Monitoring of Pollution (TEMPO) Nitrogen Dioxide Vertical Column Troposphere Provisional layer provides information on the amount of nitrogen dioxide in the troposphere, available as approximately one-hour scans for daylight hours over North America, from August 2023 to present. These data should be considered as provisional products and potentially ready for testing by operational users and may be suitable for scientific publication.
Layer Overview
The Tropospheric Emissions: Monitoring of Pollution (TEMPO) Nitrogen Dioxide Vertical Column Troposphere layer provides information on the amount of nitrogen dioxide in the troposphere. This is provided as the total number of nitrogen dioxide molecules in the tropospheric column of air above one square centimeter on the Earth’s surface (units: molecules/cm^2). Nitrogen dioxide Level 3 files provide trace gas information on a regular grid. Level 3 files are derived by combining information from all Level 2 files constituting a TEMPO East-West scan cycle, using an area-weighted re-gridding approach. The data have been converted from their native file format (netCDF4) to Cloud Raster Format (CRF).
Temporal Coverage
The temporal resolution of a nominal scan is approximately one hour during daylight hours, with more frequent scans in the morning over the eastern portion of the field of regard (FOR) and in the evenings over the western portion of the FOR. Each image is presented with the starting timestamp of the corresponding TEMPO scan. Due to the nature of the TEMPO instrument’s east to west scanning pattern, each image is a composite of measurements taken over a period of 40-60 minutes, depending on the spatial coverage of the scan. Data are updated daily with the previous day's data. Data are available from August 2023 to present.
Geographic Coverage
Imagery is available for North America. This layer is presented in its native geographic coordinate system (WGS 1984) and resolution. The sensor’s native spatial resolution is ~2 km x 4.75 km at the center of TEMPO’s FOR and the Level 3 product resolution is 0.02 x 0.02 degrees.
Data Filtering
The layer is filtered to display high-quality pixels using the main data quality flag (removing low confidence measurements), solar zenith angle (removing data retrieved at high solar zenith angles), and effective cloud fraction (removing where clouds obscure the tropospheric column) variables. The filters applied are set to remove pixels based on the following: main_data_quality_flag > 1, eff_cloud_fraction > 0.5, and solar_zenith_angle > 80.
Data Validation
These data should be considered as provisional products per the Provisional Product Maturity level defined in the TEMPO validation plan. These data are at provisional maturity, which means that product performance has been demonstrated through a large, but still (seasonally or otherwise) limited number of independent measurements. The analysis is sufficient for limited qualitative determinations of product fitness-for-purpose, and the product is potentially ready for testing by operational users and may be suitable for scientific publication. Please note that there have been no changes to the data in this image service from when it was classified as beta; therefore, users do not need to recreate imagery or redo analyses conducted while the image service data were beta. Users may consult the TEMPO User Guide for descriptions of the data and associated known issues.
Recommended Usage Notes
When viewing the image service in the ESRI online map viewer, it is recommended to use the multidimensional slider rather than the default time slider. The multidimensional slider can be accessed via the “multidimensional” icon in the right-hand menu.
TEMPO Mission Overview
The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is a grating spectrometer, sensitive to visible (VIS) and ultraviolet (UV) wavelengths of light with a spectral range of 290-490 + 540-740 nm and 0.6 nm spectral resolution. The TEMPO instrument is attached to the Earth-facing side of a commercial telecommunications satellite (Intelsat 40e) in geostationary orbit over 91˚ W longitude (about 22,000 miles above Earth’s equator). This allows TEMPO to maintain a continuous view of North America so that the instrument's light-collecting mirror can make a complete east-to-west scan of the field of regard hourly during daylight hours. By measuring sunlight reflected and scattered from the Earth's surface and atmosphere back to the instrument's detectors, TEMPO's ultraviolet and visible light sensors provide measurements of ozone, nitrogen dioxide, formaldehyde, and other constituents involved in the chemical dynamics of Earth’s atmosphere.
The primary mission objectives of TEMPO involve understanding the dynamics of air quality, pollution sources, and their impact on climate change. By providing near real-time data and comprehensive atmospheric composition measurements, TEMPO will assist scientists in studying pollution patterns, evaluating the efficacy of environmental policies, and predicting future trends in air quality.
Contact
For inquiries about this service, please contact larc-dl-asdc-tempo@mail.nasa.gov or post/view questions on the Earthdata Forum.