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Friday, July 24, 2020 | History

3 edition of Sensible heat flux measurements near a cold surface found in the catalog.

Sensible heat flux measurements near a cold surface

Yin-Chao Yen

Sensible heat flux measurements near a cold surface

by Yin-Chao Yen

  • 57 Want to read
  • 26 Currently reading

Published by U.S. Army Corps of Engineers, Cold Regions Research & Engineering Laboratory, Available from NTIS in [Hanover, N.H.], [Springfield, Va .
Written in English

    Subjects:
  • Heat -- Transmission -- Measurement,
  • Turbulence -- Measurement,
  • Low temperature research,
  • Anemometer

  • Edition Notes

    StatementYin-Chao Yen ; prepared for Office of the Chief of Engineers.
    SeriesCRREL report -- 95-22.
    ContributionsUnited States. Army. Office of the Chief of Engineers., Cold Regions Research and Engineering Laboratory (U.S.)
    The Physical Object
    Paginationvi, 43 p. :
    Number of Pages43
    ID Numbers
    Open LibraryOL17604041M
    OCLC/WorldCa34221159

    tures larger than ⫾ K, correlations with the difference in measured sensible heat flux were good. It was It was found that radiative surface temperatures, obtained from thermal infrared. In this work, sensible heat flux estimated using a bulk transfer method was validated with a three-dimensional ultrasonic anemometer or surface layer scintillometer at various sites. Results indicate that it remains challenging to obtain temperature and wind speed at an appropriate reference height. To overcome this, alternative observations using an unmanned aerial vehicle (UAV) were considered.

      The ratio of sensible heat to latent heat is called the Bowen ratio and the physics of the various processes mean that this ratio is kept to a minimum – a moist surface will hardly increase in temperature while evaporation is occurring, but once it has dried out there will be a rapid rise in temperature as the sensible heat flux takes over. In recent years, the large aperture scintillometer (LAS) has been used to measure average sensible heat flux from m to 10 km, and the measurement can be comparable to the pixel-scale fluxes.

    What other fluxes are important? We have focused on the sensible heat flux up to now, but turbulence creates other vertical fluxes. There are many vertical turbulent fluxes, but two important ones are the latent heat flux, which involves the vertical transport of water vapor, and the horizontal momentum flux, which involves the vertical transport of horizontal wind. sivities. Because a snow surface can be very cold, espe-cially at night, this can result in very stable conditions with a near-surface temperature inversion that will re-duce turbulent mixing (Male ). Uncertainty in the exchange coefficients is further complicated by the in-equality of eddy diffusivities for latent and sensible en-.


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Sensible heat flux measurements near a cold surface by Yin-Chao Yen Download PDF EPUB FB2

Books. An illustration of two cells of a film strip. Video An illustration of an audio speaker. DTIC ADA Sensible Heat Flux Measurements Near A Cold Surface Item Preview remove-circle DTIC ADA Sensible Heat Flux Measurements Near A Cold Surface by Defense Technical Information Center.

Get this from a library. Sensible heat flux measurements near a cold surface. [Yin-Chao Yen; United States. Army. Office of the Chief of Engineers.; Cold Regions Research and Engineering Laboratory (U.S.)] -- A unidirectional sonic anemometer with a fine-wire thermocouple in conjunction with a hot film anemometer were employed to measure the turbulent fluctuating velocities of W', U', and the.

{{Citation | title=Sensible heat flux measurements near a cold surface / Yin-Chao Yen ; prepared for Office of the Chief of Engineers | author1=Yen, Yin-Chao | author2=United States. Anandakumar K () Sensible heat flux over a wheat canopy: optical scintillometer measurements and surface renewal analysis estimations.

Agric For Meteorol – CrossRef Google Scholar Arya SP () Introduction to micrometeorology, 2nd by: 1. By means of the algorithm presented here, the temporal course H(t) and the daily mean H¯ of the sensible heat flux H can be estimated from measurements of the thermodynamic surface temperature (as a function of time) and from a one-time-of-day air temperature observation.

In addition to these temperatures, one needs estimates for daily mean wind speed, for the roughness lengths of Cited by: 9.

where L e is the latent heat of vaporization and is a function of sea surface temperature (SST, T s) expressed as L e =(− 37×T s)× 6. c p is the specific heat capacity of air at constant pressure; c e and c h are the stability- and height-dependent turbulent exchange coefficients for latent and sensible heat, respectively.

T a /q a are the temperature/specific humidity at a. Residue of sensible heat flux (absolute value) w/m Model Comparison at OA Site on Stable Conditions Our model Typical model. 0 0 10 20 30 40 50 60 70 80 90 time indices. Residue of sensible heat flux (absolute value) w/m Model Comparison at HJP02 Site on Stable Conditions Our model Typical model 0 Surface heat flux is a major forcing for the thermohaline circulation; it is the sum of the four terms: the incoming short-waves solar radiation, the outgoing sensible heat flux, latent heat flux, and long-wave radiation.

The net air–sea heat flux map is shown in Figure is a strong heat flux into the ocean along the equatorial band, in particular the cold tongues in both the Pacific. Sensible heat is literally the heat that can be felt. It is the energy moving from one system to another that changes the temperature rather than changing its example, it warms water rather than melting other words, it is the heat that can be felt standing near a fire, or standing outside on a [[sunny day.

Negative means that sensible heat is moving towards the surface. My book states that that would mainly occur at nighttime. During day there is a positive sensible heat flux and sensible heat moves away from the surface.

I can imagine that during the day, due to solar radiation, the surface warms up and air rises through convection and sensible. sensible heat flux may be larger in magnitude than the downward sensible heat flux that results from the pos-itive air–sea difference of potential temperature.

The measured flux thus appears to be countergradient (Andreas ). Previous studies of the sea surface sensible heat flux generally exclude countergradient heat fluxes by 1) elim. In this work, we propose a novel approach for computing surface sensible heat fluxes from a time series of thermal imagery sampled at 20 Hz.

The approach consists of using a surface energy budget, where the ground heat flux is easily computed from limited measurements using a force–restore‐type methodology, the latent heat fluxes are.

Measurements of LAS sensible heat flux can be used to validate and/or calibrate satellite estimates of sensible heat and latent energy fluxes over large areas (e.g., Watts et al. Surface layer scintillometry (SLS) is complementary to LAS in that sensible heat flux measurements between 50 and m for the former are possible.

Hukseflux company started in making sensors for measurement of heat flux in soils. In the course of the years, we have added many “special purpose” sensors and systems for other parameters of the surface energy balance. Our soil heat flux sensors and 4-component net-radiometers are popular sensors in meteorological networks.

The sensible and latent heat fluxes, H and LE, can be obtained from sonic anemometer measurements of vertical velocity w and temperature Tc and fast-response hygrometer measurements of water vapor density h2o. However, several corrections must be made to these measured quantities.

Fluxes are very small in all cases. Simulated sensible heat flux H generally compares well to EC-measured H. Differences were less than 1 W m −2 during both early and late periods (mean values 3–4 and 7–8 W m −2, respectively), although they are slightly larger (3 W m −2) during the mid period (mean values 3–6 W m −2).

Figure 2. Predicted sensible heat flux (dashed line) from observed air temperature T compared with the measurement of sensible heat flux H (solid line) made at the ABRACOS experiment site (forest) in Reserva Jaru, Ji-Parana during April' (a) T and (b)/4.

one elevation during June 19 to July 8,are illustrated in Figure 1. The sensible heat flux H was positive, that is, from the lake to the atmosphere, except in May, when it was >0 W/m 2 at night and heat flux dominated clearly over H in spring and summer; that is, the Bowen ratio was less than 1.

Higher‐moment turbulence statistics proved to be efficient in detection of frequent. • Near-surface air temperature and humidity – Roberts et al. () neural net technique Latent Heat Flux Sensible Heat Flux SeaFlux Climatological Data Set Version Ta, qa momentum and turbulent heat fluxes • Extremes: cold air outbreaks, hurricanes.

Sensible Heat. Sensible heat is the energy required to change the temperature of a substance with no phase change. The temperature change can come from the absorption of sunlight by the soil or the air itself. Or it can come from contact with the warmer air caused by release of latent heat.

The National Oceanography Centre (NOC) Version Surface Flux and Meteorological Dataset is a monthly mean gridded dataset of marine surface measurements and derived fluxes constructed using optimal interpolation.

Input for the period to are ICOADS Release ship data and the update from to uses ICOADS Release It is a positive number when it is towards the surface. • G is the Ground Heat Flux. It is the loss of energy by heat conduction through the lower boundary. It is a positive number when it is directed away from the surface into ground.

The value at the surface is denoted G0. • H is the Sensible Heat Flux. It represents the loss of energy by the.Radiation, Sensible Heat Flux and Evapotranspiration Climatological and hydrological field work Figure 1: Estimate of the Earth’s annual and global mean energy balance.

Over the long term, the incoming solar radiation absorbed by the Earth and atmosphere is balanced by the Earth and atmosphere releasing the same amount of outgoing longwave.