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United States Department of Agriculture

Agricultural Research Service

Research Project: EFFICIENT MANAGEMENT AND USE OF ANIMAL MANURE TO PROTECT HUMAN HEALTH AND ENVIRONMENTAL QUALITY

Location: Food Animal Environmental Systems Research Unit

Title: A system for estimating bowen ratio And evaporation from waste lagoons

Authors
item Quintanar, Arturo -
item Mahmood, Rezaul -
item Loughrin, John
item Lovanh, Nanh
item Motley, Monica -

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2009
Publication Date: August 10, 2009
Repository URL: http://hdl.handle.net/10113/40266
Citation: Quintanar, A.I., Mahmood, R., Loughrin, J.H., Lovanh, N.C., Motley, M.V. 2009. A system for estimating bowen ratio And evaporation from waste lagoons. Applied Engineering in Agriculture. 25(6):923-932.

Interpretive Summary: A low cost system was placed on a hog waste treatment lagoon to obtain estimates of its energy flows into and from the lagoon. The system consisted of humidity and temperature sensors and anemometers deployed above the lagoon, water temperature sensors, and a meteorological station located by the lagoon. To evaluate the system, data was analyzed during late June, 2007. There were distinct day/night differences with the lagoon absorbing energy during the day and emitting it at night. Furthermore, wind speeds above the lagoon were highest in the afternoon. These variations were linked to lagoon temperature stratifications which became more pronounced as wind speeds increased. At night the temperature stratification in the lagoon disappeared. This behavior is similar to other small bodies of water. These findings suggest that there is an increase in evaporation from the lagoon during the day. These results are important for characterizing the thermal behavior of lagoons leading to a better understanding of the processes that drive emissions of malodors and greenhouse gases from waste treatment lagoons.

Technical Abstract: A low cost system was deployed above a swine waste lagoon to obtain estimates of Bowen ratios and characterize lagoon temperatures. The system consisted of humidity and temperature sensors and anemometers deployed above the lagoon, water temperature sensors, and a meteorological station located by the lagoon. To evaluate the system, data was analyzed from the 25th through 28th June, 2007. Bowen ratios showed diurnal behavior near the lagoon surface characterized by negative values during day and positive ones at night. Latent (evaporation) and sensible heat fluxes were towards the atmosphere and the lagoon, respectively for most of the day. A diurnal cycle in atmospheric and lagoon temperatures was also observed. Furthermore, wind speeds above the lagoon were highest in the afternoon. These variations were linked to lagoon temperature stratifications which became more pronounced as wind speeds increased. Temperature stratification at the lagoon indicated increased heat exchange at the lagoon’s interface with the atmosphere. During the night, the stratification disappeared and temperatures in the water column were almost identical down to about 60 cm. This behavior is similar to that observed in other shallow water bodies that are fetch-limited. Lagoon heating was driven by the diurnal cycle of solar radiation and net radiation. This suggests that Bowen ratios had an inverse relationship with lagoon heating and its thermal stratification. This also indicates that there was an increase in latent heat flux and evaporation during the daytime. These results are important for characterizing the thermal behavior of the lagoon leading to a better representation of processes responsible for emissions.

Last Modified: 4/19/2014
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