Boundary Layer Climates.

The energetic basis of the urban heat island

I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

Principles of Terrestrial Ecosystem Ecology

Progress in urban climatology over the two decades since the first publication of the International Journal of Climatology is reviewed. It is emphasized that urban climatology during this period has benefited from conceptual advances made in microclimatology and boundary-layer climatology in general. The role of scale, heterogeneity, dynamic source areas for turbulent fluxes and the complexity introduced by the roughness sublayer over the tall, rigid roughness elements of cities is described. The diversity of urban heat islands, depending on the medium sensed and the sensing technique, is explained. The review focuses on two areas within urban climatology. First, it assesses advances in the study of selected urban climatic processes relating to urban atmospheric turbulence (including surface roughness) and exchange processes for energy and water, at scales of consideration ranging from individual facets of the urban environment, through streets and city blocks to neighbourhoods. Second, it explores the literature on the urban temperature field. The state of knowledge about urban heat islands around 1980 is described and work since then is assessed in terms of similarities to and contrasts with that situation. Finally, the main advances are summarized and recommendations for urban climate work in the future are made. Copyright © 2003 Royal Meteorological Society.

/pdf/two-decades-of-urban-climate-research-a-review-of-turbulence-12p43b6trj.pdf

Two decades of urban climate research: a review of turbulence, exchanges of energy and water, and the urban heat island

[1] We update the Goddard Institute for Space Studies (GISS) analysis of global surface temperature change, compare alternative analyses, and address questions about perception and reality of global warming. Satellite-observed night lights are used to identify measurement stations located in extreme darkness and adjust temperature trends of urban and periurban stations for nonclimatic factors, verifying that urban effects on analyzed global change are small. Because the GISS analysis combines available sea surface temperature records with meteorological station measurements, we test alternative choices for the ocean data, showing that global temperature change is sensitive to estimated temperature change in polar regions where observations are limited. We use simple 12 month (and n × 12) running means to improve the information content in our temperature graphs. Contrary to a popular misconception, the rate of warming has not declined. Global temperature is rising as fast in the past decade as in the prior 2 decades, despite year-to-year fluctuations associated with the El Nino-La Nina cycle of tropical ocean temperature. Record high global 12 month running mean temperature for the period with instrumental data was reached in 2010.

/pdf/global-surface-temperature-change-2xwuck0p9j.pdf

Global surface temperature change

Boundary-layer flow over very rough surfaces is poorly understood so the applicability of standard micrometeorological theory is uncertain. This study presents observations of the turbulent fluctuations of meteorological parameters over a suburban area. Even though the height of measurement is considered to be close to the junction between the inertial and roughness sub-layers, the wind and temperature spectra and the momentum and sensible heat flux cospectra are in good agreement with reference data from smoother surfaces. Recommendations are made concerning site requirements, height of measurement and averaging times for the study of turbulence and turbulent fluxes over suburban terrain.

/pdf/velocity-and-temperature-spectra-and-cospectra-in-an-ostb8nr8m4.pdf

Velocity and temperature spectra and cospectra in an unstable suburban atmosphere

Summertime measurements of local scale energy balance of a suburban site in west Mi- ami, Florida, in 1995 are presented. All of the radia- tion and turbulent heat fluxes were measured di- rectly. In addition several derived surface character- istics are calculated including the albedo, radiation temperature, emissivity, aerodynamic and canopy resistances, Bowen's ratio, Priestley-Taylor and Mc- Naughton-Jarvis coefficients. The results are used to test parameterizations to calculate several heat fluxes. Most radiation fluxes can be calculated with simple schemes in cloudless conditions but the spa- tial and temporal variability of cloud degrades re- sults greatly. This highlights the value of observing incoming solar radiation since it can form an excel- lent surrogate for daytime net all-wave radiation in all sky conditions. The heat flux results for this warm, wet subtropical site demonstrate similarities with those from similarly developed locations in temperate climates. Interestingly this finding in- cludes the fraction of energy used in evaporation. It is thought that this may be related to the relatively large heat storage in Miami which may reflect the presence of wet soils and free-standing water, the persistently low vapor pressure deficits (7-14 hPa) typical of this humid climate and the relatively poor coupling between the surface and the whole plane- tary boundary layer due to relatively low surface roughness.

/pdf/the-suburban-energy-balance-in-miami-florida-3zsnwuwbij.pdf

The suburban energy balance in miami, florida

Introduction, Graem Wynn views of the metropolitan area, Alfred H. Siemens the primordial environment, O. Slaymaker, et al the lower mainland 1820-81, Cole Harris the rise of Vancouver, Graeme Wynn primordial to prim order - a century of environmental change, T.R. Oke, et al Vancouver, the province, and the pacific rim, T.J. Barnes, et al Vancouver since the Second World War - an economic geography, R.N. North and W.G. Hardwick time to grow up? from urban village to world city 1966-91, D. Ley, et al the biophysical environment today, D.G. Steyn, et al epilogue, Derek Gregory.

Vancouver and its region

There is growing interest in urban dew and its significance in questions of urban climate and air pollution deposition, but little research has been undertaken to study it. In this study, a generic, urban residential neighbourhood is modelled out-of-doors at a scale of 0.125, using three wooden houses (1.08 m tall), a concrete pavement (1.0 m in width), a grassed park (7.5 m in half-width) and several small trees (up to 1.5 m tall). The thermal inertia of each house is inflated, according to the internal thermal mass (ITM) approach, so that nocturnal surface temperatures are conserved. First-order validation was achieved through comparison with data collected at nearby full-scale sites in Vancouver, BC, Canada. Moisture accumulation (measured by blotting on grass and by lysimetry) is found to be primarily controlled by nocturnal weather conditions and the intrinsic nature of each substrate, e.g. dewfall is abundant on nights with few clouds and light winds, and on surfaces such as grass and asphalt–shingle roofs, which cool rapidly after sunset. However, these responses are modified by location effects related to the net radiation balance of the surface, which itself is strongly linked to site geometry as expressed by sky view factor and whether surfaces are isolated from heat sources. The dominant mechanism is argued to be the systematic increase in longwave radiation loss that is associated with increased sky view. Results agree with those observed at the full scale and suggest that maps of sky view factor, and knowledge of dew at an open site, can potentially be used to create maps of dew distribution in urban and other complex environments. Copyright © 2002 Royal Meteorological Society.

Validation and results of a scale model of dew deposition in urban environments

Classics in physical geography revisited: Sundborg, Å. 1951: Climatological studies in Uppsala with special regard to the temperature conditions in the urban area. Geographica 22

Timothy R. Oke

Papers

Velocity and temperature spectra and cospectra in an unstable suburban atmosphere

The suburban energy balance in miami, florida

Vancouver and its region

Validation and results of a scale model of dew deposition in urban environments

Classics in physical geography revisited: Sundborg, Å. 1951: Climatological studies in Uppsala with special regard to the temperature conditions in the urban area. Geographica 22