PAR

The photosynthetically active radiation (PAR) sensors at ARM’s Bankhead National Forest (BNF) atmospheric observatory consist of 12 quantum light sensors distributed on three towers to measure how sunlight at photosynthetically active wavelengths (400–700 nanometers) penetrates the forest canopy. On the 43-meter tower (BNF supplemental site S10), sensors are located 43 m, 22 m, 10 m, and 5 m from the ground. Downwelling radiation is measured with upward-facing sensors at all heights, and upwelling radiation is measured with downward-facing sensors at 43 m and 5 m. On the two 10 m towers (BNF supplemental sites S13 and S14), upwelling radiation is measured at 8 m and 2 m, and downwelling radiation is measured at 8 m.

• Shortwave broadband total downwelling irradiance
• Shortwave broadband total upwelling irradiance