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Full catalog/OPERA_L4_TROPO-ZENITH_V1
OPERA_L4_TROPO-ZENITH_V1·v1·dataset

How much the atmosphere bends radar signals overhead

OPERA Tropospheric Correction at Zenith validated product (Version 1)
land NASA ASF Level 4 active netCDF-4XMLPNG
In plain English

What it measures. Estimates how much the atmosphere slows and bends radar signals passing straight up through it, broken into the part caused by water vapor and the part caused by dry air pressure, at different heights.

How it's made. Calculated from a weather-forecast model (Europe's ECMWF high-resolution forecast) rather than from a satellite sensor, then packaged so it can be matched to any radar mission.

How & where you'd use it. A correction input: radar scientists use it to remove atmospheric distortion from satellite radar measurements so the ground readings come out accurate. Most people would use it indirectly, baked into corrected radar products.

What's measured

SPECTRAL/ENGINEERING › RADAR

Coverage & cadence

  • Time span2016-01-01 → ongoing
  • Measured byECMWF
  • Processing levelLevel 4
  • Spatial extent-180, -90, 180, 90
  • FormatsnetCDF-4, XML, PNG
  • StatusACTIVE

What you can do with it

  • Track deforestation, fire scars and land-cover change
  • Monitor crop and vegetation health (NDVI/EVI)
  • Map how built-up vs. green an area is over time
Official description

The OPERA Level 4 Troposphere Zenith Radar Delays (TROPO-ZENITH) products are radar sensor-agnostic, one-way troposphere zenith-integrated delays, including both wet and hydrostatic components, at various height levels. Tropospheric delay in satellite radar measurements is primarily influenced by atmospheric temperature, water vapor, and pressure, which are correlated with topography. It is characterized as the integral of air refractivity from the surface up to top of the atmosphere at approximately 80 km altitude. Refractivity consists of wet and hydrostatic components that vary in space and time, driven by atmospheric pressure, temperature, and water vapor partial pressure. While hydrostatic delay is mainly governed by atmospheric pressure and temperature , wet delay is predominantly affected by water vapor content, i.e water pressure normalized by the temperature. Global estimates of these atmospheric parameters are available from Numerical Weather Prediction models, such as the European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Model high-resolution 15-day forecast (HRES) dataset, which provides the data used to compute the TROPO-ZENITH product. The TROPO-ZENITH product contains one-way zenith-integrated tropospheric delays, which must be intersected with topography elevation, projected to an imaging path and scaled to the radar wavelength to apply the two-way tropospheric correction for radar propagation. The OPERA project is funded by NASA’s Satellite Needs Working Group (SNWG) which provides data products developed to meet the needs of stakeholders from US government agencies.

Get the data

opera_l4_tropo-zenith_v1_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="OPERA_L4_TROPO-ZENITH_V1",
    version="1",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from ASF
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.