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	Bowen ratio - Wikipedia, the free encyclopedia
		A Bowen ratio is the ratio of energy fluxes from one medium to another by [[[Media:Example.ogg]]InsertformulahereInsertformulahereInsertformulahereInsertformulahereInsertformulahereInsertformulahereInsertformulahereInsertformulahereInsertformulahere--203.129.254.243 08:15, 13 April 2006 (UTC)#REDIRECT Insert text
		The quantity was named by Harald Sverdrup after Ira Sprague Bowen (1898–1973), an astrophysicist who's theoretical work on evaporation to air from water bodies made first use of it, and it is used most commonly in meteorology and hydrology.
		In this context, when the magnitude of B is less than one, a greater proportion of the available energy at the surface is passed to the atmosphere as latent heat than as sensible heat, and the converse is true for values of B greater than one.
	en.wikipedia.org /wiki/Bowen_ratio (251 words)

	Bowen Ratio Surface Flux: GSFC (FIFE)
		The Bowen ratio system consists of two sensor arms, each 1.5 meters long, which suspend the temperature sensor and air intake for the humidity sensor over the canopy.
		Sampling is performed at 1 second intervals for the Bowen ratio, 1 minute intervals for the net radiation, and 1 second intervals for soil heat flux.
		Bowen ratio (Beta) was calculated from the mean values of the vertical gradients of temperature (T) and vapor pressure (e) over the 30 minute averaging period using the surface pressure (P) and psychrometric constant (gamma):
	www-eosdis.ornl.gov /FIFE/Datasets/Surface_Flux/Bowen_Ratio_GSFC.html (3734 words)

	Irrigation Journal - Crop Coefficients - Jul/Aug 98 (Site not responding. Last check: 2007-09-17)
		The Bowen ratio energy balance method was selected as the method of estimating ETc, because it is reasonably accurate and the instruments can be made portable.
		The Bowen ratio energy balance instruments that were constructed in this project were tested in fields with lysimeters to compare ET estimates.
		Bowen ratio system and dividing that by the sum of the ETo estimates provided by the local CIMIS weather station for the same daylight hours that the instrument was collecting data in the field.
	www.greenmediaonline.com /ij/1998/0798/798crop.asp (2149 words)

	Measurements of Surface Fluxes
		It is partitioned between sensible and latent heat flux according to the ratio of careful measurements of the difference in air temperature between two heights to the difference in water vapor pressure between the same two heights.
		During IFC 4, however, they show Bowen ratio values of sensible heat flux to be 29% and 19% higher and of latent heat flux to be slightly smaller than eddy correlation values observed at the two sites.
		After including the uncertainty in the Bowen ratio determination and errors due to non-homogeneous site conditions, we estimate the overall uncertainty in individual flux determinations by the Bowen ratio method to be between 10% to 30% of the fluxes.
	esm.versar.com /FIFE/Summary/Sur_flux.htm (4688 words)

	Bowen Ratio Surface Flux: USGS (FIFE)
		Each Bowen ratio station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat.
		The Bowen Ratio Surface Flux Observations (USGS) at site 6912-BRW were collected by L. Weaver and D.I. Stannard, both at the USGS Water Resources Division in Denver, Colorado.
		The Bowen ratio, B {a ratio of the transport or gradient equations of sensible heat, H, and latent heat, E} is given by:
	www-eosdis.ornl.gov /FIFE/Datasets/Surface_Flux/Bowen_Ratio_USGS.html (4015 words)

	Tamarix (Site not responding. Last check: 2007-09-17)
		A Bowen ratio energy balance was conducted over a Tamarix ramosissima (saltcedar) stand growing in a riparian corridor along the Virgin River in southern Nevada.
		A field study to quantify Bowen ratio ET estimates of Tamarix ramosissima (Ledeb) was conducted during 1994 - 1996 along the lower Virgin River (southern Nevada).
		A Bowen ratio energy balance (BREB) approach was used to estimate canopy level ET by Tamarix (Bowen 1926).
	www.unlv.edu /Faculty/devitt/virgin.htm (1788 words)

	Bowen ratio versus canopy chamber CO2 fluxes on sagebrush rangeland by Douglas A. Johnson, Nicanor Z. Saliendra, John ... (Site not responding. Last check: 2007-09-17)
		Bowen ratio versus canopy chamber CO2 fluxes on sagebrush rangeland by Douglas A. Johnson, Nicanor Z. Saliendra, John W. Walker, and John R. Hendrickson
		Bowen ratio versus canopy chamber CO fluxes on sagebrush rangeland
		The objective of this study was to compare the Bowen ratio-energy balance and canopy chamber techniques for measuring CO2 fluxes in a sagebrush-steppe ecosystem.
	uvalde.tamu.edu /jrm/Sep03/Johnson.htm (393 words)

	[No title]
		Bowen ratio, weather, and supplementary data were collected at MS003 from DOY 162 to DOY 171.
		The average Bowen ratio was calculated by dividing the total LE measured during the period into the total H measured during the period.
		Bowen ratios at MS002 and MS003 were similar, and Bowen ratios at MS001 and MS004 were similar.
	hydrolab.arsusda.gov /washita92/datarpt/chap5.htm (2538 words)

	WRIR 99-4079 -- Abstract
		ET was calculated from energy fluxes measured and computed from the Bowen ratio for each 20-minute interval, except for those intervals having missing or inaccurate data or during which the Bowen ratio solution was unstable.
		Energy-budget fluxes and daily ET calculated from the Bowen ratio at CMEADW for the 5-day period, September 1-5, 1996, are shown in figure 11.
		Another factor contributing to the higher ratio is that the dense mat of dead vegetation (1 to 3 ft thick) and the marsh plant structure (tall and broad-leafed) work together to reduce evaporative losses.
	pubs.usgs.gov /wri/wri994079/text/evapotranspiration.htm (3085 words)

	Scientia Agricola - Energy balance in irrigated wheat in the cerrados region of Central Brazil (Site not responding. Last check: 2007-09-17)
		The Bowen ratio method was employed to measure evapotranspiration because it is valid for conditions of non-neutral stability (Huband and Monteith, 1986), it is widely used as a convenient standard against which other techniques have been compared (Sharma, 1983, Huband and Monteith, 1986, Luchiari Jr.
		In contrast to 1982, under the advective conditions of 1983 some values of the Bowen ratio are negative but are otherwise generally close to zero after canopy closure (Figure 5b).
		Given the low Bowen ratios measured during most of both growing seasons, irrigating when the soil water potential reached -60 to -70 J/kg was considered adequate and efficient.
	www.scielo.br /scielo.php?pid=S0103-90161997000300011&script=sci_arttext&tlng=en (3608 words)

	Australian Agronomy Conference - Papers
		The comparison of evapotranspiration measured by the RCM with the Bowen ratio (BR) method (2, 6) was conducted in the centre of a field of actively growing winter wheat at Moree, in northern New South Wales, on 19 and 20 August, 1997.
		It is suspected that the Bowen ratio method slightly overestimates the ET values, when the temperature is declining toward the end of the day.
		The Bowen ratio method differs in that ET is determined at 10 minute time intervals before being averaged over a 30 minute period.
	www.csu.edu.au /special/agronomy/papers/31/31.html (1843 words)

	Ira Bowen Bibliography
		Bowen, I.S., “The Presence of Neutral Oxygen in the Gaseous Nebulae,” Phys.
		Bowen, I.S., “The Chemical Composition of the Nebulae,” PASP 46, 186-87 (1934).
		Bowen, I.S., “The Spectrum and Composition of the Gaseous Nebulae,” Ap.J. Bowen, I.S., “The Galactic Nebulae,” Scientia 59, 77-86 (1936).
	www.phys-astro.sonoma.edu /BruceMedalists/Bowen/BowenRefs.html (1061 words)

	DETERMINATION OF GLOBAL HEAT FLUX BOWEN RATIO USING SATELLITE REMOTE SENSING DATA (Site not responding. Last check: 2007-09-17)
		Hicks and Hess'(1977) linear regression formula for the analytical Bowen ratio was used to estimate the Bowen ratio in the tropical Pacific.
		However relative Bowen ratio error was smaller over the western Pacific and a larger margin of error was found over the eastern Pacific due to the complicated interaction of the humidity, wind, and other variables.
		Assumptions about the analytical Bowen ratio was agrees well with weak wind and high humidity over the western Pacific, which had negative phase of the humidity and positive phase of the winds on the relative Bowen ratio, respectively.
	www.iugg.org /iapso/abstracts/IJ-01/IJ01-21.htm (261 words)

	Bruce Metelerkamp's MSc Thesis Abstract (titled "The use of the Bowen Ratio Energy Balance Method for the ...
		The Bowen Ratio Energy Balance (BREB) is one method that can be used to provide sub-hourly evaporation estimates required for research, local irrigation scheduling and monitoring of remote sites.
		The Bowen ratio energy balance method, as applied, can accurately and continuously measure evaporation from a mountainous catchment, providing the fetch and advection requirements as set out, have been met.
		Due to the formulation of Bowen ratio theory, failure of the system at times of low evaporative flux (due to low available energy near sunrise and sunset) can be expected.
	homepages.ihug.co.nz /~metz/bruce/appendx.htm (1480 words)

	Plant Physiology Online: Heat Dissipation from Leaves: The Bowen Ratio (Site not responding. Last check: 2007-09-17)
		When the evaporation rate is low, because water supply is limited, the Bowen ratio tends to be high.
		Thus, the Bowen ratio is about 10 for deserts, 2-6 for semi-arid regions, 0.4 to 0.8 for temperate forests and grasslands, 0.2 for tropical rain forests and 0.1 for tropical oceans (Nobel 1999)
		In these conditions there is no sensible heat loss, because the air around the leaf is at the same temperature as the leaf; the Bowen ratio therefore approaches zero, and heat dissipation is due mostly to evaporative heat loss.
	www.plantphys.net /printer.php?ch=9&id=132 (483 words)

	Your Heading Goes Here (Site not responding. Last check: 2007-09-17)
		Typical values for the Bowen ratio are 0.1 for tropical oceans; 0.1-0.3 for tropical wet jungles; 0.4-0.8 for temperate forests and grassland; 2.0-6.0 for semi-arid areas; and greater than 10.0 for deserts
		The Bowen ratio is defined as the ratio of sensible heat to latent heat (Equation 2).
		It is common practice in the Bowen ratio technique to measure the wet bulb depression at two levels using psychrometers to determine the water vapour gradient.
	www.arts.monash.edu.au /subjects/ges/ges2190/BR_theory.htm (1975 words)

	ARS \| Publication request: The Bowen Ratio-Energy Balance Method for Estimating Latent Heat Flux of Irrigated Alfalfa ...
		Interpretive Summary: The Bowen ratio-energy balance (BREB) is a micrometeorological method often used to quantify crop water use, investigate plant-water relations, and evaluate crop water use models.
		Technical Abstract: The Bowen ratio-energy balance (BREB) is a micrometeorological method often used to estimate latent heat flux because of its simplicity, robustness, and cost.
		The smallest daytime difference of the BREB method compared with lysimeters was when Bowen ratios were between 0 and 0.3.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=104760 (439 words)

	CHAPTER X. MICROMETEOROLOGICAL MEASUREMENTS
		The fetch to height ratio was in excess of 200 along the north-south transect and 100 along the east-west transect.
		Evaporative fraction defined as the ratio between latent heat and net radiation fluxes will be analyzed to evaluate diurnal trends as a function of surface cover.
		Bowen, I.S. The ratio of heat losses by conduction and by evaporation from any water surface.
	hydrolab.arsusda.gov /washita94/chap10.htm (3267 words)

	Nat' Academies Press, Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs (2003)
		The Bowen ratio is the ratio of the sensible heat to the latent heat.
		The Bowen ratio method fails under conditions of low energy availability such as during the night or during periods of precipitation.
		Like all of the micrometeorological methods, the Bowen ratio technique is subject to errors associated with the chemical and micrometeorological sensors and the spatial and temporal variability of fluxes within the source area of interest.
	www.nap.edu /books/0309087058/html/94.html (791 words)

	Water Supply Paper 2430 Abstract
		A mean-gradient Bowen ratio system was used to measure and average vertical air temperature and vapor-pressure gradients, and the Bowen ratio was computed using the mean air temperature and vapor-pressure gradients.
		Measurements made using the mean-gradient Bowen ratio system at a forested pine flatwood site indicated that vapor-pressure gradients were too weak to be resolved by the system.
		The Bowen ratio obtained from eddy correlation measurements was then combined with measurements of available energy to compute evapotranspiration by the EBBR method.
	fl.water.usgs.gov /Abstracts/wsp2430_bidlake.html (748 words)

	A study of land-atmosphere interactions during summertime rainfall using a mesoscale model
		Analysis of the dynamics of moisture and energy states in the boundary layer for all model grid cells revealed the existence of dual limit cycles in the model's phase space of Bowen ratio and relative humidity.
		Specifically, the dual limit cycles suggest two distinct regimes of land-atmosphere interactions: (1) a divergent (splitting) trajectory of increasing diurnal variations of Bowen ratio and relative humidity for persistently dry weather conditions and (2) a convergent (merging) trajectory of rapidly decreasing Bowen ratio and increasing relative humidity for wet weather conditions.
		Regionally, the footprint of these two regimes of land-atmosphere interactions is apparent in the correlation between Bowen ratio and the vertical distribution of relative humidity in the troposphere.
	www.agu.org /pubs/crossref/2002/2000JD000254.shtml (430 words)

	Plant Physiology Online: Heat Dissipation from Leaves: The Bowen Ratio
		Plants with very high Bowen ratios conserve water but have to endure very high leaf temperatures in order to maintain a sufficient temperature gradient between the leaf and the air.
		Very low Bowen ratios can be measured in a lawn on a relatively still day.
		In that case, there is sensible heat gain rather than heat loss, and the Bowen ratio becomes negative.
	www.plantphys.net /article.php?ch=t&id=132 (483 words)

	CE520 Physical Hydrology - Homework
		Use both the aerodynamic method and the empirical Penman equation for the evaluation of the drying power of the air, and compare your results.
		Obtain the Bowen Ratio implied by the equilibrium evaporation rate and compare with the Bowen Ratio obtained in part b.
		Obtain the Bowen Ratio implied by this rate of evaporation under conditions of minimal advection.
	www.engr.colostate.edu /~ramirez/ce_old/classes/ce520_ramirez/Homework_2_2003.htm (263 words)

	ET Study
		Reginato and Jackson (1992) compared porometer and normal curve methods (Groeneveld and Warren, 1992), similar to those in the Green Book, to Bowen ratio and eddy correlation measurements; however, the LAI and percent-cover measurements were not made concurrently with the micrometeorological measurements, rendering the evaluation of the Green Book method inconclusive.
		Tyler et al.’s (1997) comparison of Bowen ratio and eddy correlation methods was done on the Owens Lake lakebed for establishing a water budget and estimating salt flux from the lakebed.
		They found that the eddy correlation method agreed better with lysimeter measurements than did Bowen ratio measurements, and concluded that low evaporation rates from the playa surface resulted in such low humidity gradients that the Bowen ratio method was unreliable.
	www.inyowater.org /ICWD_Reports/cstudy_ET.htm (4033 words)

	ARM - Instruments: Energy Balance Bowen Ratio Station
		The content of the ARM website is available to any browser, but for the best experience we highly recommend you upgrade to a standards-compliant browser such as the latest version of Mozilla, Netscape, Internet Explorer, or Opera (all available for free download).
		The Energy Balance Bowen Ratio (EBBR) system produces 30 min estimates of the vertical fluxes of sensible and latent heat at the local surface.
		Flux estimates are calculated from observations of net radiation, soil surface heat flux, and the vertical gradients of temperature and relative humidity.
	www.arm.gov /instruments/instrument.php?id=ebbr (210 words)

	A Review of "A Coupled Study of the Exchange of Carbon Cycle Gases at the Surface and in the Column of the Atmosphere ...
		The ratio of the dry heat flux to the evaporative energy flux, referred to as the Bowen ratio, is a key parameter for the determination of evapotranspiration.
		At a larger scale, the Bowen ratio can also be used to quantify the degree of convective coupling between land and atmosphere, and hence the role of terrestrial ecosystems in climate variability and change.
		Under these conditions the flux of any trace gas is proportional to the change in mixing ratio of that gas in the PBL relative to the free troposphere multiplied by the mean vertical velocity through the top of the PBL.
	www.archive.arm.gov /Carbon/dataneeds/review.html (2276 words)

	ABLE Energy Balance Bowen Ratio (EBBR) Station (Site not responding. Last check: 2007-09-17)
		The ABLE Energy Balance Bowen Ratio (EBBR) Station provides in situ half-hour averages of the surface vertical fluxes of sensible heat, latent heat, net radiation, and soil surface heat flux.
		The fluxes are obtained by the energy balance Bowen ratio technique, a gradient method that uses vertical gradients of temperature and relative humidity in combination with point measurements of net radiation and soil heat flow from 5 sets of soil sensors.
		The Bowen ratio is measured as the ratio of the gradients of temperature and vapor pressure (the latter calculated from relative humidity and temperature) across two fixed heights within 3 meters of the surface.
	www.atmos.anl.gov /ABLE/ABLEEBBRWebPage.html (1184 words)

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