15:00–15:15 | ABSTRACT 1199
BACKSCATTERING BY < 0.2 UM PARTICLES IN THE OCEANS
We measured the angular scattering functions at 517 nm in different size fractions, including bulk and particles of sizes <0.2 µm in diameter (very small particles, VSP), in a variety of waters ranging from coasts to open oceans and from surface to depths as deep as 3000 m. The measurements revealed a strong covariation in backscattering between these very small particles and bulk particle populations. The fractional contribution by VSP decreases from 60% in clear oceanic water where bulk particle backscattering coefficient bbp is on the order of 0.001 m–1 to <1% in turbid coastal water where bbp ~ 0.1 m–1. An empirical model is developed (R2 = 0.89) to estimate bbp for VSP from the bulk bbp, which can now be routinely obtained from satellite observations. The study shed light onto a key question that has perplexed the ocean optics community regarding the source of backscattering in the oceans. It also provides a new perspective in examining particles in the operationally defined dissolved domain, in addition to absorption by CDOM that has been routinely measured.
Xiaodong Zhang, The University of Southern Mississippi, [email protected], https://orcid.org/0000-0002-2982-210X
Yuanheng Xiong, The University of Southern Mississippi, Division of Marine Science, [email protected], https://orcid.org/0000-0001-5263-576X
