Uncertainties of surface turbulent flux measurements and the impacts on the derived large-scale forcing at the ARM SGP site
Poster PDF
Authors
Shuaiqi Tang — Pacific Northwest National Laboratory
Shaocheng Xie — Lawrence Livermore National Laboratory
Qi Tang — Lawrence Livermore National Laboratory
Yunyan Zhang — Lawrence Livermore National Laboratory
Minghua Zhang — Stony Brook University
David R. Cook — Argonne National Laboratory
Category
ARM infrastructure
Description
Two types of instruments, the eddy correlation flux measurement system (ECOR) and the energy balance Bowen ratio system (EBBR), are used at the Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site to measure surface latent and sensible fluxes. During summer months, ECOR usually measures smaller latent heat and larger sensible heat fluxes than EBBR. This is partly because that ECOR and EBBR typically sample different land surface types, with EBBR almost always looking at grassland while ECOR looking at grassland, cropland or forest, depending on the site and wind directions. Winter wheat is planted on most of cropland at SGP, which is usually drier than grassland during summer. When the data are filtered in certain wind directions to make sure ECOR and EBBR see the same surface, the differences are much smaller. We propose a new method to calculate the domain-mean surface turbulent fluxes based on the surface types seen by the instruments and investigate the sensitivity. The uncertainties of the surface fluxes will have impacts on the derived large-scale forcing data, especially on the vertical velocity. This will further affect the simulations of single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulation models (LES).
