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Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010)

We are all familiar with the fact that cities are generally warmer than the surrounding, more rural areas. We see it referenced most nights in our television weather reports. It is especially significant on nights with clear skies and light winds which favor radiational cooling. This is most significant in the rural areas but in the city, the excess heat absorbed during the day and the local heat sources maintain higher nighttime readings. During the days or nights with strong winds and clouds the differences are minimzed due to mixing and the advective cooling of the city by the winds.

The urban heat island

Urban heat island (UHI) has been evidenced as a phenomenon having a series of negative consequences in energy use, human thermal comfort, citizens' health, wellbeing and air quality. Thus, all professions, faculties and disciplines of society are actively seeking for effective UHI mitigation techniques and strategies. Previous studies have indicated that synoptic variables such as wind, precipitation, cloud coverage, fog and air quality have significant impacts on UHI phenomenon. In accordance with this basis, we devise to develop UHI mitigation techniques and strategies based on meteorological characteristics and synoptic conditions. This paper therefore has reviewed the influences of meteorological characteristics and synoptic conditions, such as precipitation, wind, cloud coverage, fog, air pollution and haze on UHI effects. Through this work, people can obtain better understandings of using them to mitigate UHI effects. Meanwhile, some suggestions on urban planning and development have been briefly presented for the alleviation of UHI effects.

Potentials of meteorological characteristics and synoptic conditions to mitigate urban heat island effects

1. After du Bois-Reymond [7] had constructed the example of a continuous function whose Fourier series diverges at apoint Jordan [12] gave a new criterion for convergence of Fourier series which introduced a new class of functions: B V. It was followed by several, today classical, theorems about the behavionr of Fourier series of functions of this class. We are concerned with one of them, essentially due to L. Fej6r [9] (see atso Czillag [5]).

Rendiconti del circolo matematico di Palermo

Cities are particularly vulnerable to meteorological hazards because of the concentration of population, goods, capital stock and infrastructure. Urban climate services require multi-disciplinary and multi-sectorial approaches and new paradigms in urban climate modelling. This paper classifies the required urban input data for both mesoscale state-of-the-art Urban Canopy Models (UCMs) and microscale Obstacle Resolving Models (ORM) into five categories and reviews the ways in which they can be obtained. The first two categories are (1) land cover, and (2) building morphology. These govern the main interactions between the city and the urban climate and the Urban Heat Island. Interdependence between morphological parameters and UCM geometric hypotheses are discussed. Building height, plan and wall area densities are recommended as the main input variables for UCMs, whereas ORMs require 3D building data. Recently, three other categories of urban data became relevant for finer urban studies and adaptation to climate change: (3) building design and architecture, (4) building use, anthropogenic heat and socio-economic data, and (5) urban vegetation data. Several methods for acquiring spatial information are reviewed, including remote sensing, geographic information system (GIS) processing from administrative cadasters, expert knowledge and crowdsourcing. Data availability, data harmonization, costs/efficiency trade-offs and future challenges are then discussed.

City-descriptive input data for urban climate models: Model requirements, data sources and challenges

Urban canopy parameters (UCPs) are essential in order to accurately model the complex interplay between urban areas and their environment. This study compares three different approaches to define the UCPs for Moscow (Russia), using the COSMO numerical weather prediction and climate model coupled to TERRA_URB urban parameterization. In addition to the default urban description based on the global datasets and hard-coded constants (1), we present a protocol to define the required UCPs based on Local Climate Zones (LCZs) (2) and further compare it with a reference UCP dataset, assembled from OpenStreetMap data, recent global land cover data and other satellite imagery (3). The test simulations are conducted for contrasting summer and winter conditions and are evaluated against a dense network of in-situ observations. For the summer period, advanced approaches (2) and (3) show almost similar performance and provide noticeable improvements with respect to default urban description (1). Additional improvements are obtained when using spatially varying urban thermal parameters instead of the hard-coded constants. The LCZ-based approach worsens model performance for winter however, due to the underestimation of the anthropogenic heat flux (AHF). These results confirm the potential of LCZs in providing internationally consistent urban data for weather and climate modelling applications, as well as supplementing more comprehensive approaches. Yet our results also underline the continued need to improve the description of built-up and impervious areas and the AHF in urban parameterizations.

Impact of urban canopy parameters on a megacity’s modelled thermal environment

The river runoff regime significantly changed worldwide in the end of twentieth – the beginning of twenty-first century. In the European part of Russia the current changes are manifested in...

Evaluating climate and water regime transformation in the European part of Russia using observation and reanalysis data for the 1945–2015 period

Many lakes at different stages of separation from the sea were formed along the coast of Kandalakshsky Gulf of the White Sea because of a rapid glacioisostatic lifting. The natural stage of their hydrological evolution is the meromixis. Five stratified lakes at different stages of isolation were studied in 2010-2014. The studies included echo-sounding of bottom topography, measurements of hydrological parameters: temperature, salinity, pH, redox potential, oxygen content, as well as registration of organoleptic properties of water, and in situ illumination measurements at different depths. Data from four years of observation are generalized, the vertical structure of the lakes was determined, as well is its seasonal and interannual variations. The lakes are ranked by chronology of their separation from the sea.

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Salt lakes separated from the white sea

The study applies object-oriented analysis to the extraction of urban canyons and introduces the concept of directed urban canyon which is then being experimentally applied in urban meteorological modeling. Summary of current approaches for describing urban canyon geometry is provided. Then a new theoretical approach to canyon delineation and three-level hierarchical classification is presented. The study discloses an original methodology based on triangular irregular network (TIN) designed to allow extraction of directed and undirected urban canyons from cartographic data and estimation of their geometric characteristics. Obtained geometric properties of canyons are coupled with land cover data into the database, which is then applied in micro-to-local scale temperature and wind modeling. Using URB_MOS model and the derived database we refined COSMO_RU modeling results which facilitated the decrease of the mean root square error of temperature forecast from 4.0 to 2.1 degrees. Estimation of possible wind accelerations along canyons using the derived database is also presented. Results and future perspectives are summarized in the concluding part.

Object-oriented approach to urban canyon analysis and its applications in meteorological modeling

Line generalization is an essential data processing operation in geographic information systems and cartography. Many point reduction and simplification algorithms have been developed for this purpose. During the last three decades, several attempts have been made to develop approaches of generalization that adapt to the geometric properties of the processed lines. They typically incorporate line segmentation based on quantitative descriptions of the line shape. Little attention has been paid to the cases in which heterogeneous lines of different geometric character are mixed in one dataset. One common example is administrative borders, which often contain natural and artificial, smooth and sharp, schematic and non-schematic, and regular and irregular shapes. The tuning of the simplification algorithm based on a quantitative description of the shape would be ineffective here, since different algorithms must be applied to lines of different characters. In this article, we present a general method a...

Timofey Samsonov

Papers

Impact of urban canopy parameters on a megacity’s modelled thermal environment

Evaluating climate and water regime transformation in the European part of Russia using observation and reanalysis data for the 1945–2015 period

Salt lakes separated from the white sea

Object-oriented approach to urban canyon analysis and its applications in meteorological modeling

Shape-adaptive geometric simplification of heterogeneous line datasets