Observations are direct measurements of the Earth’s climate system, collected from instruments like weather stations, satellites, buoys, and aircraft, or from natural records (tree rings, ice cores, and sediments). They provide the foundational data for tracking temperature, precipitation, sea level, and many other variables over time. Observational data is essential for understanding current conditions and detecting trends or extremes. Observations are the most direct and accurate representation of what is happening but can have gaps, especially in remote areas, hard to measure variables or over long time scales. Also used for validating models and understanding current trends.
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Important Data links and catalogues
You can find important observational data records through the following links.
- ECV Inventory (CEOS/CGMS) - The Essential Climate Variables (ECV) Inventory houses existing and planned data records from various space agencies.
- The Earth Science Data Systems (ESDS) Program - provides open access to NASA’s archive of Earth science data, empowering researchers and decision makers to better understand and protect our home planet.
- Met Office Hadley Centre observations datasets - Researchers at the Met Office Hadley Centre produce and maintain a range of gridded datasets of meteorological variables for use in climate monitoring and climate research.
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Other resources
The Earth Observation Handbook
The CEOS Earth Observation Handbook presents the main capabilities of satellite Earth observations, their applications and a systematic overview of present and planned CEOS agency Earth observation satellite missions and their instruments.
NASA Eyes on the Earth
Fly along with NASA's Earth science missions in real-time, monitor Earth's vital signs like Carbon Dioxide, Ozone and Sea Level, and see satellite imagery of the latest major weather events, all in an immersive, 3D environment.
CSA page on Earth Observation Satellites
Learn how Earth observation satellites provide data on oceans, ice, land environments, and the atmosphere, or explore different satellite missions that are operated or supported by the Canadian space agency.
Important Observation related terms
These are some concepts that are specifically important in relation to observations.
- Metadata - Descriptive info about data (e.g., instrument type, location, calibration history) that's crucial for proper interpretation.
- Proxy Data - Indirect climate evidence (e.g., tree rings, ice cores) used to infer past climate conditions before modern instruments.
- Quality Control (QC) Flags- Indicators attached to data points that flag potential issues like errors, gaps, or suspect readings.
- Coverage Bias - Gaps or uneven distribution in spatial or temporal data that affect the representativeness of observations.
- Reprocessing - Re-analysis of raw observational data using updated algorithms or corrections to improve accuracy and consistency.
- Ground Truthing - Using direct, on-the-ground measurements to validate or calibrate remote sensing data, often from satellites.
- Instrument Drift - Gradual changes in instrument response over time, affecting long-term measurement consistency.
- Homogenization - Techniques used to adjust observational time series to account for non-climate-related changes (like station relocations or equipment updates).
- Radiometric Calibration - The process of converting raw satellite sensor data into physical units like temperature or radiation.
- Inhomogeneities - Discontinuities or biases in a climate record caused by changes in instruments, observing practices, or environment.