albedometers

An albedometer is a sensor that measures surface albedo, the fraction of incoming solar radiation reflected by a surface. The instrument is typically built around two calibrated broadband pyranometers mounted on a common frame so their optical fields of view are matched to the target surface.

In a standard configuration, one pyranometer points upward to quantify the incident shortwave irradiance reaching the surface, while the other points downward to capture the radiation reflected by the surface. The albedo is calculated as the ratio of the reflected irradiance to the incident irradiance, usually expressed as a number between 0 and 1 (or as a percentage). Some systems employ a spectrally resolved sensor or separate channels to determine spectral albedo across visible to near-infrared wavelengths.

Albedometers can be deployed on the ground, mounted on towers, or used in field campaigns. They are used in climate and cryosphere research, vegetation and soil studies, urban heat island investigations, and energy balance measurements. They are often paired with data loggers and meteorological sensors to provide concurrent measurements of temperature, wind, and humidity.

Measurement considerations include maintaining a cosine-corrected, unobstructed view of the surface, shielding from stray light, and accounting for solar angle and atmospheric effects. Regular calibration against known radiometric references is required to maintain accuracy, along with routine maintenance of sensor domes to minimize spectral and directional biases.