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.

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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.

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Global surface temperature change

The ‘Sunset’ neigborhood in Vancouver, BC, may be the most extensively studied area in urban climatology. Since 1977, about 50 papers have been published that focus on flux measurements, land-atmosphere exchange, and models developed using data gathered on and around the ‘Vancouver-Sunset’ micrometeorological tower. This newsletter contribution aims to provide a brief history of this unique flux tower, show how selected developments in urban climatology were linked to work at this site, and highlight some of the ongoing research on urban trace-gas flux measurements to validate fine-scale emission models.

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35 years of urban climate research at the 'Vancouver-Sunset' flux tower

Measuring Nocturnal Longwave Radiative Flux Divergence

A LiDAR-based approach for anthropogenic heat release modeling by buildings at the urban neighbourhood-scale

Measuring Longwave Radiative Flux Divergence in an Urban Canyon

A technique to identify inhomogeneities in historical temperature records caused by microclimatic changes to the surroundings of a climate station is presented Because site characteristics can have a pronounced influence on the nocturnal cooling process, this technique uses daily maximum and minimum temperatures to construct time series of monthly ‘cooling ratios’ for the test station and a neighbouring reference station Hurst rescaling is applied to the time series of cooling ratios to aid in the identification of change points, or inflections, which signal microclimatic change in one of the station records These change points are then compared to documented station history events, provided that sufficient metadata exists Results for a variety of air temperature records, ranging from rural to urban stations, are presented to illustrate the applicability of the technique

Timothy R. Oke

Papers

35 years of urban climate research at the 'Vancouver-Sunset' flux tower

Measuring Nocturnal Longwave Radiative Flux Divergence

A LiDAR-based approach for anthropogenic heat release modeling by buildings at the urban neighbourhood-scale

Measuring Longwave Radiative Flux Divergence in an Urban Canyon

A technique to detect microclimatic inhomogeneities in historical temperature records