Concerning light at different locations

I spoke about photosynthetically active radiation and explained the meaning, and usual values, of photosynthetically active radiation (PAR), photosynthetic photon flux density (PPFD), and daily light integral (DLI). I explained that PAR can be estimated for any location, given latitude and day of the year, for a clear day with no clouds. At the field day on March 8, I further explained how different intensities of cloud cover tend to affect the PPFD. Similar calculations of solar radiation allow one to estimate the evapotranspiration for a site, again given the date and the latitude, and I demonstrated this ET calculator that uses the Hargreaves equation: https://asianturfgrass.shinyapps.io/ET_calculator/.

Transcript

1. Concerning light at di erent locations Micah Woods Chief Scientist Asian Turfgrass Center www.asianturfgrass.com 7 March 2016
2. PAR, PPFD, and DLI What do these mean? PAR is photsynthetically active radiation. It is the light with wavelengths from 400 to 700 nm.
3. PAR, PPFD, and DLI What do these mean? PAR is photsynthetically active radiation. It is the light with wavelengths from 400 to 700 nm. PAR is measured instantaneously as a flux of photons within those wavelengths on a surface of 1 m2.
4. PAR, PPFD, and DLI What do these mean? PAR is photsynthetically active radiation. It is the light with wavelengths from 400 to 700 nm. PAR is measured instantaneously as a flux of photons within those wavelengths on a surface of 1 m2. Instantaneous PAR is the photosynthetic photon flux density, (PPFD). In full sun at midday in summer, the PPFD will be about 2,000 micromoles of photons per square meter per second.
5. PAR, PPFD, and DLI What do these mean? PAR is photsynthetically active radiation. It is the light with wavelengths from 400 to 700 nm. PAR is measured instantaneously as a flux of photons within those wavelengths on a surface of 1 m2. Instantaneous PAR is the photosynthetic photon flux density, (PPFD). In full sun at midday in summer, the PPFD will be about 2,000 micromoles of photons per square meter per second. Adding together all the PAR from each second of the day gives the daily light integral, DLI. For ultradwarf bermudagrass, the maximum possible DLI is best. For minimum acceptable quality, the DLI should be at least 30 moles per square meter per day.
6. PPFD meter
7. Bangkok, no clouds, 7 March 2016 3 7 54.1 mo d dli 0 500 1000 1500 2000 4 6 8 10 12 14 16 18 20 Time of day PPFD, µmol m-2 s-1
8. Bangkok & Manila, 7 March 2016 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 mo d 0 500 1000 1500 2000 4 6 8 10 12 14 16 18 20 Time of day PPFD, µmol m-2 s-1 BKK MNL
9. Bangkok & Manila & Tokyo, 7 March 2016 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 mo d 0 500 1000 1500 2000 4 6 8 10 12 14 16 18 20 Time of day PPFD, µmol m-2 s-1 BKK MNL TYO
10. Field day tomorrow at Phoenix