9/25/2024 URBAN CLIMATOLOGY Part 1. Motivation to study urban climates, objectives, historical overview Outline Ten lectures, no preliminary knowledge required 1. Motivation to study urban climates, historical overview 2. Main factors controlling urban climate (UC), UC scales, energy balance 3. The climate of Brno as an example (data, methods, main outcomes) 4. Urban heat Island (UHI), UHI types, atmospheric UHI, UHI intensity 5. Urban Remote Sensing, surface UHI 6. Precipitation in urban areas 7. Spatio-temporal variability of other meteo elements in urban areas 8. Urban climate classification 9. Urban Climate Modelling 10. Urban adaptation to climate change Practical seminar - Local Climate Zones mapping - independent full-semester work with a short presentation of results at the end (Dec 4th) Conclusion - oral exam - answer two simple questions plus discussion on Your LCZ mapping results 1 Paper to read Urban Climate 10 (2014) 479-489 Contents lists available al ScienceDirect Urban Climate journal homepage: www.elsevier.Gom/lacate/uclim Urban climatology: History, status and prospects ^&OS5Mari Gerald Mills School of Geography, Planning & Environmental Policy, UCD, Dublin, Ireland https://is.muni.cz/auth/el/sci/podzirri2024/ZA311/urri/67875456/01 Mills 2014.pdf Useful sources https://urban-climate.org/teaching-resources/ https://lcz-generator.rub.de/ 1.1 Objective Climate in urban areas differ from that of rural areas due to process of urbanization. _ Manhattan-Mannahatta: on right is a reconstruction of Manhattan Island circa 1609 (called "Mannahatta"), as compared to today, based on historical landscape ecology and map data. • First phase of urbanization (initiated by the industrial revolution) • Second phase (uncontrolled development in less-developed countries) • Problem of sustainability • As for climate, urbanization means ... 1.1 Objective • Most meteorological elements and climatological characteristics have specific features of their spatial and temporal variability in urbanized areas • However, typical spatiotemporal variability of urban climate in individual cities is formed as a superposition of natural and anthropogenic factors atmosph Urban biosphi Urban hydrosphere pedo- and lithosphere Oke et al., 2017, Urban Climates ) Cambridge University Press 2017 Built system The biophysical components of an urban ecosystem. They include all aspects of the pre-urban natural environment subsequently modified by the introduction of built infrastructure Urban climate = natural climate variability + urban forced climate variability 1.1 Objective • Specific features of urban climate may strongly affect economic activities, infrastructure functioning, quality of life, etc. goods Oke et al., 2017, Urban Climates © Cambridge University Press 2017 The representation of the inputs to, and outputs from, an urban ecosystem (concept of urban metabolism). 1.1 Objective Urban climatology objective is to study: a) How cites impact climate b) How urban climate impacts cities and their dwellers Built-up areas create specific category of local climate - urban climate 10H Regional scale Bourikas, 2016 The peculiarities of the urban climate can be studied at the level of the mesoclimate, local climate or microclimate categories 1.2 Climate 10J 1 10' 10° 10° 10B Climate categories: The hierarchy of climate scales from global to regional to meso-scale to local to ] micro-scale 10 mm 1 in 1 km 1,000 km Oke etai, 2017, Urban Climates Characteristic horizontal distance scale (in) For local climate it is typical that the processes in the lower layers of the atmosphere are significantly shaped by the radiation, thermal, aerodynamic, and moisture properties of active surfaces. 1.2 Urban Climate concept Active surface - transition between the atmosphere and the lithosphere or hydrosphere (surface of soil, water, vegetation, roads, roofs of houses, etc.), on which radiation energy is reflected and/or transformed into other types of energy (primarily heat). In cities, active surfaces create complicated hierarchy: Urban region a u 10 City (bulit up area) Neighbourhood (LCZ) Block Canyon Element Facet 1 AntfrrapBgirric full i . 1 I LMkH Ml Active surface influences atmospheric processes in the boundary layer of the atmosphere through its physical and chemical properties (relief height, orientation, albedo, thermal conductivity, humidity, soil composition and structure, vegetation, ...). 1.2 Motivation - the target is ... SMART, green and climate neutral cities Regenerative and prosperous urban economies Equitable, engaged and empowered communities Connected, healthy and climate friendly 11 lifestyles Urban sustainability ©https://www2.helsinki.fi Sustainable city as a new Utopia? However, at first we have to describe, quantify, analyze impact, etc. How we can do it? Urban effect estimate Table 2.4 Methods lo attempt estimation of the 'urban effect1 using observations. Urbar>-p re-urban difference Difference between obj^rvngcini at the lame mil on ü its environment channel rram naluril (fJ) to urban I• due to urbanization. Contributions the IT KfDdtfttWB (V[,) and topographic context (V, J do not vary over period line* Urbanization began Satiora th^t capture the trance*mirJon af a landscape from natural to urtwn are very m e. Background dimate may change due to long wrm global or rcpartal climate change. Urban—rui difference _- downwind J rriT.iK<- ratio nil v» DnTerefi-ce. hc*wMn Obl*r%4tiOHt it two Stations located in adjacent rural (A) jnd •:■-■■>■■ {LT) iT*li. Contribution* <>f arid V; are ti»e ■mi nc ndl site 'or weather conditions nnd period e*arnined. M«a3urenicnu In a r\»ral -ar« (ft) arc not equivalent, to pre-u rban values; the character of the rural contribution to VfH chaises: station ma/open to advatflCfi from urban yr&a, hence urhnn-iffecned {A). (Vjwiüj^/^Wf*—) Deference (or ratio) between observations at Two stations focated in j njnl Ird upwind ([ftl vp). and one downwind, erf an urban area (tifbirwrfected (A) Awn). ConUibutions of u» and V. are the Difficult to find HMtCHU that meet lamt at each site rtw weather the requirements because urban- condldons (especial\f wind direction! affected area (A.) unVnown at and periid ikimiried. SHrcol t^U ^mly nivS Hi hliapt? and extent owllatro with weather, especially wind direction. Weekday-weekend Differoyict A-nrv/tKin obstratfoni aC the u--ne station, subdivided i n to (li^tc on weekdays (w doy) and WBufiterrds ar hft'idays {w'entfi. Contributions of Vt and V\ are the Weekend or holiday observations same for wtekday and weektrtd are not the equivalent of prc-urban datawts. Alio magniiudJt and pattern valutt bttausc human activity is of human activities have not chafed not absent effects of urban form signincandy o^er period examined. {fabric, cover and structure) are present in both >eu Of values. Are there any other approaches? 1.3 Motivation • Over the last 200 years, the global population has increased sevenfold and the fraction of the people living in urban areas increased from 3% to 50% (UN, 2015) • Importance of urban climate studies increase in recent decades due to global climate change Global Warming 1850 to 2023 HadCRUT5 GISTEMP NOAA ECMWF Berkeley Earth 95% confidence interval shown ror Berkeley Earth Temperature anomalies relative to 1981-2010 average 0.8 0.6 p 0.4 J 0.2 § o I 0.2 I QJ -0.4 I -0.6 t rn -O -0.8° h11ps://berkeleyearth.org/global-1empera1ure-report-for-2023/ 1.3 Motivation It is very probable that the frequency and intensity of hydrometeorological extremes will be higher in the near future New Scientist European heatwave caused 35,000 deaths Heat wave in the western Europe: temperature differences between July 2003 and July 2001 http://earthobservatory.nasa.gov/NaturalHazards 1.3 Motivation ft Annual number of tropical days (a), tropical nights (b), number (c) and intensity (d) of heat waves in Brno, airport station in the 1961-2020 period Higher heat load and higher extremity of weather and climate may negatively influence living conditions in urban areas with the direct impact to quality of life and health of population Any positive impacts? Better know/ledge of causes and mechanisms that form urban climate are necessary for the mitigation of negative impacts and for the realization of adaptation strategies 1.4 History Antiquity (VTTRUVIUS: 'DE ARCHITECTURAL middle ages Bad quality of air in the cities, air pollution Luke Howard (1772-1864) The Climate of London (1833) 1 II III IV V VI VII Mil IX \ \l XII Jilll. Feb. Mai: Apr. May Jun. July. Aug. Sep. Oil. Vcro Dee. - II h - il - - A comparison between the air temperature observations by Luke Howard (solid) against those made by the Royal Society within London (broken). Source: Howard (1833), 1.4 History • 21th century • Classification - concept of Local Climate Zones • Urban climate modelling (WRF, MUKLIMO_3D, ENVIMET) • Practical realisation of adaptation and mitigation measures • www. urban-climate, org/ Urban Climate Change Research Network • http://uccrn.org/ 1.5 Future prospects Improving scientific knowledge (the urban effect on precipitation) To overcome the paucity of information on the rapidly growing cities of the less prosperous regions Rapid advances in sensor technologies, problem of appropriate measurement devices and methods More realistic descriptions of land cover; better characterization of the city structure: material properties, geometry, and functions (traffic) Development of models (physical, numerical) Concept urban - rural is regionally different and mostly pays for mid-latitudes; rural mostly does not mean natural but managed natural 1.6 Definitions Urban climatology is concerned with the study of the climate effect of urban areas and the application of the knowledge acquired to the better planning and design of cities. Descriptive climatology Despite the accumulation of evidence (e.g. on the urban air temperature effect), much of it was specific to particular places and used distinct methods that made generalisations difficult. AIu *(max) =2.96 log P-6.41 Physical climatology Adopts a quantitative and systematic approach to research. Its the most common expression was formulation of the surface energy balance in cities. d* = Q.H + Q.E + Q.G The research focus was shifted from describing effects (responses) to seeking their cause (processes). 9/25/2024 1.7 Final remarks and questions i. Is it an actual problem to study urban climates? 2. What do you know about history of urban meteorology and climatology? 3. What is the difference between "descriptive" and "physical" urban climatology? 4. May there be any positive aspects of the recent climate change in urban environment? 5. What are the main topics of urban climatology in the near future? 11