- Aerosol optical depth mapping from multispectral imagers — Aerosol optical depth (AOD) quantifies how much sunlight a column of atmosphere scatters or absorbs. Satellites retrieve it at multiple wavelengths, separating dust, smoke, and sulphate pollution by spectral fingerprint and Ångström exponent, with known limits over bright surfaces.
- GNSS radio occultation for atmospheric profiling — When a GNSS signal grazes Earth's limb before reaching a low-orbit receiver, its path curves in proportion to atmospheric density. Inverting that curve yields precise vertical profiles of temperature, pressure, and water vapour from the surface to roughly 60 km altitude, with no calibration drift and near-global coverage every six hours.
- Atmospheric CO₂ and CH₄ column measurement for climate-treaty datasets — OCO-2, OCO-3, GOSAT-2 and TROPOMI retrieve column-averaged CO₂ and CH₄ from shortwave infrared spectra, giving treaty bodies an independent check on national greenhouse-gas inventories. The technique is powerful but cloud-biased and cannot directly invert surface fluxes without modelling.
- Ice-sheet surface elevation change from photon-counting lidar — ICESat-2's photon-counting lidar resolves ice-surface elevation change to a few centimetres per year, giving glaciologists and policymakers the most precise public record of ice-sheet geometry available from orbit.
- Ice-sheet mass balance from satellite gravimetry — Twin satellites ranging each other to millimetre precision detect month-to-month shifts in Earth's gravity field caused by ice-mass loss over Greenland and Antarctica. The technique is the only operational method for whole-ice-sheet mass budgets, but its 300 km resolution floor means it cannot pinpoint which glacier is responsible.
- Global lightning climatology from optical sensors in geostationary orbit — High-frame-rate optical sensors in geostationary orbit detect the 777.4 nm oxygen triplet emission from lightning, enabling continuous global flash mapping tied to convective intensity and climate variability.
- Saharan and Asian dust plume transport tracking — Mineral dust lofted from the Sahara and Asian deserts can travel thousands of kilometres, disrupting aviation, agriculture and public health. Satellites detect and track these plumes using UV absorbing aerosol index, thermal infrared brightness-temperature differences, and lidar backscatter profiles.
- Sea-level rise measurement from radar altimetry — Nadir-pointing Ku-band radar altimeters on a continuous satellite series have measured global mean sea-level change since 1992 at millimetre-per-year precision, revealing thermal expansion, ice-melt contributions, and regional divergence from the global mean.
- Sea-surface temperature retrieval for oceanography and fisheries — Satellite SST combines thermal infrared precision with microwave all-weather coverage to track ocean heat at daily global scales. The physics of each method sets hard limits on what you can know, and where.
- Surface soil moisture retrieval for drought monitoring — L-band microwave radiometry measures the dielectric contrast between wet and dry soil to retrieve volumetric moisture in the top 5 cm, globally. SMOS and SMAP are the dedicated missions; Sentinel-1 SAR fills the resolution gap they cannot close.
- Stratospheric ozone column monitoring for treaty verification — Total ozone column and vertical ozone profiles retrieved from UV backscatter and occultation instruments provide the long-term, calibrated record needed to verify Montreal Protocol compliance and track the stratosphere's slow recovery.
- Tropospheric humidity retrieval from microwave sounders — Passive microwave sounders near 183 GHz retrieve tropospheric humidity profiles through cloud cover that defeats every optical instrument. This page explains the physics, the key instruments, and what the data honestly can and cannot resolve.
- Urban heat island intensity mapping from thermal infrared — Land surface temperature retrieved from thermal infrared satellites reveals the urban heat island with quantified intensity. Landsat TIRS reaches 100 m resolution; MODIS and ECOSTRESS offer different trade-offs between revisit and detail.
- Volcanic SO₂ plume tracking and emission quantification — UV backscatter spectrometry on TROPOMI and OMPS retrieves sulphur dioxide column amounts daily at sub-kilometre to tens-of-kilometres scale, enabling near-real-time aviation hazard alerts and long-run climate forcing estimates, with honest caveats on altitude ambiguity and low-altitude degassing blind spots.