John L. Monteith

Bio: John L. Monteith is an academic researcher from International Crops Research Institute for the Semi-Arid Tropics. The author has contributed to research in topics: Atmosphere & Transpiration. The author has an hindex of 58, co-authored 138 publications receiving 30024 citations. Previous affiliations of John L. Monteith include Goddard Space Flight Center & University of Nottingham.

Chapter 1 the Physics of the Microclimate

Abstract: Publisher Summary This chapter discusses the physics of the microclimate. The thermal environment affects man through the transfer processes between his body and its surroundings. The mechanisms of these processes are outlined in the chapter. Complete specification of a thermal environment is obviously a complex problem and in general it is necessary to describe not only the temperature gradient between a subject and the fluid (usually air) in which he is immersed, but also the respective transfer coefficients for evaporation, convected sensible heat and radiation, and the radiant field. Because of the complexity of real environments, within buildings and in the open air, effective temperature indices have been developed. The aim of these indices is to specify the environment by a single number in units of temperature, which is the most easily understood determinant of heat loss. Such indices may help to specify comfortable or tolerable environments with greater precision. However, man's perception of the environment is complicated by his own psychological and physiological reactions.

I. Angular distribution of incoming radiation

Abstract: SUMMARY The apparent emissivity of the atmosphere t', defined as the ratio of incoming long-wave radiation to black-body radiation at screen temperature To, was measured under clear skies in the English Midlands and in the Sudan. At a zenith angle Z the emissivity was given by

Reflection and Review

Abstract: The papers presented at this meeting have given us a comprehensive account of the state of the art in what one is tempted to call ‘forest meteorology’ though ‘meteorological forestry’ is probably nearer the mark. Older members of the audience like myself who can recall the descriptive and anecdotal nature of the subject in the early 1950s have enjoyed hearing how it has come of age through the painstaking collection of measurements in the field and through the emergence of principles that have guided the development of mathematical models. Forest meteorologists have been fortunate that much of the foundation of their subject has been laid by the pioneers of agricultural meteorology who have had an easier task experimentally and are therefore a little ahead, but not much! A psychologist might have felt quite at home at this meeting because there have been so many references to the way systems ‘behave’. It seemed that systems were ‘well behaved’ when processes being observed were consistent with theoretical predictions where they existed, or with intuition where they did not. Bad behaviour (by a forested catchment in Rob Roy’s territory for example) meant a discrepancy between performance and expectation. We should remember, however, that the recognition of so-called bad behaviour is the first step towards new developments in most branches of science; and that progress in forest meteorology will depend on the skill and patience of people who feel challenged to tackle the anomalies, the uncertainties and the loose ends that we have heard about yesterday and today.

Crop evapotranspiration : guidelines for computing crop water requirements

Abstract: (First edition: 1998, this reprint: 2004). This publication presents an updated procedure for calculating reference and crop evapotranspiration from meteorological data and crop coefficients. The procedure, first presented in FAO Irrigation and Drainage Paper No. 24, Crop water requirements, in 1977, allows estimation of the amount of water used by a crop, taking into account the effect of the climate and the crop characteristics. The publication incorporates advances in research and more accurate procedures for determining crop water use as recommended by a panel of high-level experts organised by FAO in May 1990. The first part of the guidelines includes procedures for determining reference crop evapotranspiration according to the FAO Penman-Monteith method. These are followed by updated procedures for estimating the evapotranspiration of different crops for different growth stages and ecological conditions.

Large Area Hydrologic Modeling and Assessment Part i: Model Development

Abstract: A conceptual, continuous time model called SWAT (Soil and Water Assessment Tool) was developed to assist water resource managers in assessing the impact of management on water supplies and nonpoint source pollution in watersheds and large river basins. The model is currently being utilized in several large area projects by EPA, NOAA, NRCS and others to estimate the off-site impacts of climate and management on water use, nonpoint source loadings, and pesticide contamination. Model development, operation, limitations, and assumptions are discussed and components of the model are described. In Part II, a GIS input/output interface is presented along with model validation on three basins within the Upper Trinity basin in Texas.

Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components

Abstract: Integrating conceptually similar models of the growth of marine and terrestrial primary producers yielded an estimated global net primary production (NPP) of 104.9 petagrams of carbon per year, with roughly equal contributions from land and oceans. Approaches based on satellite indices of absorbed solar radiation indicate marked heterogeneity in NPP for both land and oceans, reflecting the influence of physical and ecological processes. The spatial and temporal distributions of ocean NPP are consistent with primary limitation by light, nutrients, and temperature. On land, water limitation imposes additional constraints. On land and ocean, progressive changes in NPP can result in altered carbon storage, although contrasts in mechanisms of carbon storage and rates of organic matter turnover result in a range of relations between carbon storage and changes in NPP.

Correction of flux measurements for density effects due to heat and water vapour transfer

Abstract: When the atmospheric turbulent flux of a minor constituent such as CO2 (or of water vapour as a special case) is measured by either the eddy covariance or the mean gradient technique, account may need to be taken of variations of the constituent's density due to the presence of a flux of heat and/or water vapour. In this paper the basic relationships are discussed in the context of vertical transfer in the lower atmosphere, and the required corrections to the measured flux are derived. If the measurement involves sensing of the fluctuations or mean gradient of the constituent's mixing ratio relative to the dry air component, then no correction is required; while with sensing of the constituent's specific mass content relative to the total moist air, a correction arising from the water vapour flux only is required. Correspondingly, if in mean gradient measurements the constituent's density is measured in air from different heights which has been pre-dried and brought to a common temperature, then again no correction is required; while if the original (moist) air itself is brought to a common temperature, then only a correction arising from the water vapour flux is required. If the constituent's density fluctuations or mean gradients are measured directly in the air in situ, then corrections arising from both heat and water vapour fluxes are required. These corrections will often be very important. That due to the heat flux is about five times as great as that due to an equal latent heat (water vapour) flux. In CO2 flux measurements the magnitude of the correction will commonly exceed that of the flux itself. The correction to measurements of water vapour flux will often be only a few per cent but will sometimes exceed 10 per cent.