An experimental study in micro‐meteorology

Swinbank, W. C.; Dyer, A. J.

doi:10.1002/qj.49709339808

Cited by 104 publications

(51 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The second concern is the assumption of similarity for the eddy diffusivities. Similarity theory is based on the argument that the turbulent transport of both heat and water vapor, along with any other scalar quantity, is dependent only on the turbulent motion of the parcel of air composing the eddy (Swinback and Dyer 1967). However, the eddy diffusivities may not be similar when the sources for the various scalar quantities are not identically distributed (McNaughton and Laubach 1998) or when advective processes persist on local or regional scales (Lee et al 2004;Gavilá n and Berengena 2007).…”

Section: Theoretical Considerations a Bowen Ratio Energy Balance Methodsmentioning

confidence: 99%

Concerning the Measurement and Magnitude of Heat, Water Vapor, and Carbon Dioxide Exchange from a Semiarid Grassland

Alfieri

Blanken

Smith

et al. 2009

Journal of Applied Meteorology and Climatology

View full text Add to dashboard Cite

Grassland environments constitute approximately 40% of the earth's vegetated surface, and they play a key role in a number of processes linking the land surface with the atmosphere. To investigate these linkages, a variety of techniques, including field and modeling studies, are required. Using data collected at the Central Plains Experimental Range (CPER) in northeastern Colorado from 25 March to 10 November 2004, this study compares two common ways of measuring turbulent fluxes of latent heat, sensible heat, and carbon dioxide in the field: the eddy covariance (EC) and Bowen ratio energy balance (BREB) methods. The turbulent fluxes measured by each of these methods were compared in terms of magnitude and seasonal behavior and were combined to calculate eddy diffusivities and examine turbulent transport. Relative to the EC method, the BREB method tended to overestimate the magnitude of the sensible heat, latent heat, and carbon dioxide fluxes. As a result, substantial differences in both the diurnal pattern and long-term magnitudes of the water and carbon budgets were apparent depending on which method was used. These differences arise from (i) the forced closure of the surface energy balance and (ii) the assumption of similarity between the eddy diffusivities required by the BREB method. An empirical method was developed that allows the BREB and EC datasets to be reconciled; this method was tested successfully using data collected at the CPER site during 2005. Ultimately, however, the BREB and EC methods show important differences that must be recognized and taken into account when analyzing issues related to the energy, water, or carbon cycles.

show abstract

Section: Theoretical Considerations a Bowen Ratio Energy Balance Methodsmentioning

confidence: 99%

Concerning the Measurement and Magnitude of Heat, Water Vapor, and Carbon Dioxide Exchange from a Semiarid Grassland

Alfieri

Blanken

Smith

et al. 2009

Journal of Applied Meteorology and Climatology

View full text Add to dashboard Cite

show abstract

“…The use of a common eddy diffusivity and, hence, of a common local stability function for all scalar quantities is based on some empirical results that the turbulent transfer of sensible heat and water vapor is similar (e.g., [48,79,80]), which is adopted to the other scalars as well (e.g., [52,81,82]). This is in agreement with some empirical results derived from concurrent measurements of ozone fluxes and ozone profiles [83].…”

Section: The Turbulent Numbers Of Schmidt Prandtl and Lewis-semenovmentioning

confidence: 99%

Similarity Hypotheses for the Atmospheric Surface Layer Expressed by Non-Dimensional Characteristic Invariants – A Review

Kramm¹,

Herbert²

2009

TOASCJ

View full text Add to dashboard Cite

Abstract:In this paper, similarity hypotheses for the atmospheric surface layer (ASL) are reviewed using nondimensional characteristic invariants, referred to as -numbers. The basic idea of this dimensional -invariants analysis (sometimes also called Buckingham's -theorem) is described in a mathematically generalized formalism. To illustrate the task of this powerful method and how it can be applied to deduce a variety of reasonable solutions by the formalized procedure of non-dimensionalization, various instances are represented that are relevant to the turbulence transfer across the ASL and prevailing structure of ASL turbulence. Within the framework of our review we consider both (a) MoninObukhov scaling for forced-convective conditions, and (b) Prandtl-Obukhov-Priestley scaling for free-convective conditions. It is shown that in the various instances of Monin-Obukhov scaling generally two -numbers occur that result in corresponding similarity functions. In contrast to that, Prandtl-Obukhov-Priestley scaling will lead to only one number in each case usually considered as a non-dimensional universal constant.Since an explicit mathematical relationship for the similarity functions cannot be obtained from a dimensionalinvariants analysis, elementary laws of -invariants have to be pointed out using empirical or/and theoretical findings. To evaluate empirical similarity functions usually considered within the framework flux-profile relationships, so-called integral similarity functions for momentum and sensible heat are presented and assessed on the basis of the friction velocity and the vertical component of the eddy flux densities of sensible and latent heat directly measured during the GREIV I 1974 field campaign.

show abstract

“…In the turbulent region of the atmosphere, eddy diffusivities for all the conserved scalars are generally assumed equal because they are carried by the same eddies and, therefore, are associated at source (Swinbank and Dyer, 1967). There is evidence to suggest k H is greater than k E under stable (early morning and late afternoon) conditions when heat gets transferred more efficiently than the water vapour (Katul et al, 1995) and when the effects of lateral advection of heat are significant (Verma et al, 1978).…”

Section: Bowen Ratio Methodologymentioning

confidence: 99%

Components of near-surface energy balance derived from satellite soundings – Part 2: Noontime latent heat flux

et al. 2014

View full text Add to dashboard Cite

Abstract. This paper introduces a relatively simple method for recovering global fields of latent heat flux. The method focuses on specifying Bowen ratio estimates through exploiting air temperature and vapour pressure measurements obtained from infrared soundings of the AIRS (Atmospheric Infrared Sounder) sensor onboard NASA's Aqua platform. Through combining these Bowen ratio retrievals with satellite surface net available energy data, we have specified estimates of global noontime surface latent heat flux at the 1 • × 1 • scale. These estimates were provisionally evaluated against data from 30 terrestrial tower flux sites covering a broad spectrum of biomes. Taking monthly average 13:30 data for 2003, this revealed promising agreement between the satellite and tower measurements of latent heat flux, with a pooled root-mean-square deviation of 79 W m −2 , and no significant bias. However, this success partly arose as a product of the underspecification of the AIRS Bowen ratio compensating for the underspecification of the AIRS net available energy, suggesting further refinement of the approach is required. The error analysis suggested that the landscape level variability in enhanced vegetation index (EVI) and land surface temperature contributed significantly to the statistical metric of the predicted latent heat fluxes.

show abstract

An experimental study in micro‐meteorology

Cited by 104 publications

References 6 publications

Concerning the Measurement and Magnitude of Heat, Water Vapor, and Carbon Dioxide Exchange from a Semiarid Grassland

Concerning the Measurement and Magnitude of Heat, Water Vapor, and Carbon Dioxide Exchange from a Semiarid Grassland

Similarity Hypotheses for the Atmospheric Surface Layer Expressed by Non-Dimensional Characteristic Invariants – A Review

Components of near-surface energy balance derived from satellite soundings – Part 2: Noontime latent heat flux

Contact Info

Product

Resources

About