Li-cor, Inc.

Liukang Xu

Dayle K McDermitt

George G Burba

Tyler Anderson

Michael D Furtaw

Bradley Alan Riensche

Xiaomao Lin

Dave Johnson

Anatoly Komissarov

Dayle Mcdermitt

Systems and methods for measuring turbulent gas flux using high-speed vertical wind speed measurements (e.g., on the order of 5-10 Hz or more frequently) and low-speed gas content measurements (e.g., on the order of 5 Hz or less frequently), without the need for the sophisticated and expensive high-speed hardware to separate gas samples (e.g., into accumulation bags) according to updrafts and downdrafts. A time series of high-speed vertical wind speed data is used as a guide to distinguish between updrafts and downdrafts. When vertical wind speed is upward (updraft), the low-speed gas content is recorded into a data structure in one location, or marked with one flag. When vertical wind speed is downward (downdraft), the low-speed gas content is recorded into a different location, or marked with a different flag. Eddy Accumulation or Relaxed Eddy Accumulation computations can be performed using the stored gas content data to determine gas flux.

Methods and apparatus for measuring gas flux

A system and method to obtain correct gas density and flux measurements using (i) gas analyzer (open-path, or closed-path gas analyzers with short intake tube, or any combination of the two); (ii) fast temperature or sensible heat flux measurement device (such as, fine-wire thermocouple, sonic anemometer, or any other device providing fast accurate gas temperature measurements); (iii) fast air water content or latent heat flux measurement device (such as, hygrometer, NDIR analyzer, any other device providing fast accurate gas water content measurements); (iv) vertical wind or sampling device (such as sonic anemometer, scintillometer, or fast solenoid valve, etc.) and (v) algorithms in accordance with the present invention to compute the corrected gas flux, compensated for T-P effects. In case when water factor in T-P effects is negligible, the fast air water content or latent heat flux measurement device (item iii in last paragraph) can be excluded.

Method and apparatus for determining gas flux

Disclosed embodiments of the present invention provide means to obtain correct gas density and flux measurements using (i) gas analyzer (open-path, or closed-path gas analyzers with short intake tube, for example 1 m long, or any combination of the two); (ii) fast temperature or sensible heat flux measurement device (such as, fine-wire thermocouple, sonic anemometer, or any other device providing fast accurate gas temperature measurements); (iii) fast air water content or latent heat flux measurement device (such as, hygrometer, NDIR analyzer, any other device providing fast accurate gas water content measurements); (iv) vertical wind or sampling device (such as sonic anemometer, scintillometer, or fast solenoid valve, etc.) and (v) algorithms in accordance with the present invention to compute the corrected gas flux, compensated for T-P effects. In case when water factor in T-P effects is negligible, the fast air water content or latent heat flux measurement device (item iii in last paragraph) can be excluded.

A method and apparatus are provided for maintaining pressure inside a closed chamber equal to the changing outside pressure, detecting leaks in the plumbing (i.e., air handling system) of a trace gas flux measurement system, and estimating the kinetic volume, e.g., of such a system.

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Lincoln, NE, United States of America

Liukang Xu