825 / 2024-09-19 15:28:16
Research on Heat Flux and Aerosol Flux Observations in Open Surface-Water Areas Based on Large Aperture Scintillometer
large aperture scintillometer,sensible heat flux,aerosol flux
Session 70 - Internal Waves and Ocean Mixing
Abstract Accepted
The aerosol and heat fluxes in the near-surface layer impact weather, climate, and air quality. Quantifying aerosol flux and sensible heat flux data is beneficial for analyzing atmospheric changes, predicting weather patterns, and evaluating atmospheric environments. Direct observation of these fluxes is challenging; traditional methods usually rely on eddy covariance technique for calculations. The complexity of aerosol particle properties and the diversity of characterizations, such as optical properties and composition variation, make observational difficulties significant, and there is little mutual validation. This study utilizes a large aperture scintillometer (LAS) developed by Yuan et al. (2015，2024) from the University of Science and Technology of China to observe aerosol and sensible heat fluxes over open waters. The experiment was conducted at Siyuan Lake in the Minhang campus at Shanghai Jiao Tong University, with the LAS set up at both the northern and southern ends of the lake, approximately 290 meters apart and 3 meters above the ground. The observation period was from August 10 to September 20, 2024. Additionally, a CSAT3B sonic anemometer and a PWD50 visibility meter were placed in the middle of the path to validate LAS measurements. The high-frequency and low-frequency ends of the LAS spectrum correspond to the atmospheric equivalent refractive index structure parameter (Cn,Re&Im
), and single-point visibility and wind speed data can also be converted to Cn,Re&Im
for calculation of sensible heat and aerosol fluxes. The study shows that the voltage spectrum distribution from lake observations closely matches the theoretical distribution, with low-frequency data under 1 Hz and high-frequency data ranging from 1 to 100 Hz, effectively filtering high-frequency and low-frequency data. The low-frequency variance shows more regularity, with a diurnal pattern of higher daytime values and lower nighttime values, and significant daytime fluctuations which peaks up to ten times higher than nighttime values. Aerosol flux variation during the day is within ±
0.5 μg∙m-2∙s-1
, with nighttime variation much lower, almost within ±0.1 μg∙m-2∙s-1, possibly related to atmospheric stability and fountain in the lake during the daytime. The daily average aerosol flux ranges from 0 to 0.1 μg∙m-2∙s-1. The LAS data trends are similar to those from eddy covariance principle and effectively capture turbulent fluxes.
), and single-point visibility and wind speed data can also be converted to Cn,Re&Im for calculation of sensible heat and aerosol fluxes. The study shows that the voltage spectrum distribution from lake observations closely matches the theoretical distribution, with low-frequency data under 1 Hz and high-frequency data ranging from 1 to 100 Hz, effectively filtering high-frequency and low-frequency data. The low-frequency variance shows more regularity, with a diurnal pattern of higher daytime values and lower nighttime values, and significant daytime fluctuations which peaks up to ten times higher than nighttime values. Aerosol flux variation during the day is within ±0.5 μg∙m-2∙s-1, with nighttime variation much lower, almost within ±0.1 μg∙m-2∙s-1, possibly related to atmospheric stability and fountain in the lake during the daytime. The daily average aerosol flux ranges from 0 to 0.1 μg∙m-2∙s-1. The LAS data trends are similar to those from eddy covariance principle and effectively capture turbulent fluxes.