A
Gaps in Knowledge and Practice for the Next Decade in Urban Meteorology

Grimmond et al. (2009) identified where improvements in Observations, Data, Understanding, Modeling, Tools, and Education are needed to ensure that in the next decade Urban Meteorology supports the development of more sustainable cities. Prioritization is indicated as high (H), medium (M) or low (L). These areas are reproduced below:

OBSERVATIONS

  • Need operational urban meteorological networks (within and around the city) with optimum balance between resolution and practicability, which include: surface-based instrumentation (soil moisture and air/soil/surface temperature), vertical profiles (from within the deep urban canopy layer to the top of the boundary layer) of temperature, humidity, wind, turbulence, radiation, rainfall, air quality (gases and particles, precursors and secondary), reflectivity and refractivity. (H)

  • Need observations over and within a larger range of urban morphologies to establish universal flow and flux characteristics. Need to ensure that there are long term data sets (rather than short term campaigns) that have wide spatial representativeness. The existing long term measurement stations should be preserved. (H)

  • Need to measure fluxes of CO2 using eddy covariance approach combined with isotopic analysis to determine not only the sizes of these fluxes but also to identify emission sources (e.g., background concentration, gasoline combustion, natural gas combustion and respiration) to evaluate the role of cities on the Earth-atmosphere carbon exchange. (H)

  • Need to undertake measurement studies to validate quantitative estimates of anthropogenic heat and moisture emissions and improve estimation



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A Gaps in Knowledge and Practice for the Next Decade in Urban Meteorology Grmmond et al. (2009) dentfied where mprovements n observatons, Data, Understandng, Modelng, tools, and educaton are needed to ensure that n the next decade Urban Meteorology supports the development of more sustanable ctes. Prortzaton s ndcated as hgh (H), medum (M) or low (L). these areas are reproduced below: OBSERVATIONS • need operatonal urban meteorological networks (wthn and around the cty) wth optmum balance between resoluton and practcablty, whch nclude: surface-based nstrumentaton (sol mosture and ar/sol/surface temperature), vertical profiles (from wthn the deep urban canopy layer to the top of the boundary layer) of temperature, humdty, wnd, turbulence, radaton, ranfall, ar qualty (gases and partcles, precursors and secondary), reflectvty and refractvty. (H) • need observatons over and wthn a larger range of urban morpholo- gies to establsh unversal flow and flux characterstcs. need to ensure that there are long term data sets (rather than short term campagns) that have wde spatal representatveness. the exstng long term measurement sta- tions should be preserved. (H) • need to measure fluxes of co usng eddy covarance approach 2 combned wth sotopc analyss to determne not only the szes of these fluxes but also to dentfy emsson sources (e.g., background concentraton, gasolne combuston, natural gas combuston and respraton) to evaluate the role of ctes on the earth-atmosphere carbon exchange. (H) • need to undertake measurement studes to valdate quanttatve est- mates of anthropogenc heat and mosture emssons and mprove estmaton 153

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154 154 WHen WeAtHeR MAtteRs technques at a range of scales startng wth the ndvdual buldng where measurements can close the energy budget on a control volume. (M) • need smultaneous measurements of flow propertes at varous stes and levels to better study coherent structures and ntermttent ventlaton processes wthn the roughness sublayer. (M) • need to better assess urban surface characterstcs (e.g., emssvty to develop methods to correct for thermal ansotropy), and determne fluxes from remote sensng. (M) • need to explore the use of new measurement technques ncludng the use of remote sensng technologes and smaller, more moble and af- fordable nstruments. (M) DATA • need to meet data requrements to allow translaton of research find- ngs nto urban/buldng desgn tools and gudelnes for dfferent clmate zones and classes of urban land-use. (H) • need to ensure that data are provded n a format that s usable for a broad range of practtoners wthout compromse to scentfic accuracy and ntegrty. (H) • need to ensure metadata to descrbe nstrument, stng, qualty assur- ance and control features and documentaton are complete and comparable by creatng, and usng, a standardzed urban protocol. (H) UNDERSTANDING • need to develop methods and frameworks to analyse atmospherc data measured above complex urban surfaces. ths ncludes measurement source areas to ensure representatve results and meanngful comparson between stes. (H) • need to know more about the outer layer of the urban boundary layer (UBL), .e., the atmosphere above the nternal surface layer (IsL). (H) • need to assess for each nterventon what scale nterventons are needed and possble (e.g., legally, economcally, plannng, techncally, etc.) to make ctes more sustanable (e.g., lvable, healthy, etc.). (H) • need for assessment of human-nduced large-scale clmate change at the scale of ctes to ensure that the sgnal of clmate change s dstngushed from the nose of natural varablty. (H) • need to better understand the couplng of surface and ar tempera- tures. (M)

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APPenDIX A 155 • need to examne ventlaton and pollutant removal mechansms (upward and sdeward) for 3D street canyons. (M) • need to understand f urban canopes are a specal class of rough wall or canopy flows and to what extent urban resdual surface layer (RsL) turbulence can be descrbed wth a possbly modfied mxng layer model. (M) • need to ncrease our knowledge on the subsurface heat sland. (L) MODELLING • need to evaluate urban land surface schemes n both offlne and onlne mode for a wde range of condtons to ensure that the models are fit for purpose. (H) • need to mprove short-range, hgh-resoluton numercal predcton of weather, ar qualty, and chemcal dsperson n the urban zone through mproved modelng of the bogeophyscal features of the land surface and consequent exchange of heat, mosture, momentum, and radaton (.e., the surface energy balance, seB) wth the UBL. (H) • need cFD/Les studes of wnd and pollutant transport studes n regmes other than skmmng flow and wth combned effects of wnd and buoyancy. (H) • need to mprove understandng of feedback mechansms between the urban envronmental condtons and human actvty. (H) • need to ncorporate more realstc ar polluton chemstry mecha- nsms (e.g., o ttraton at urban canopy level) nto models. (M) 3 • need to further develop mult-scale modelng to allow nvestga- tons such as: effect of large-scale atmospherc turbulence on the neghbor- hood- or even mcro-scale turbulence below the canopy levels; nteracton between natural and artfical landscapes; to assess street-level comfort, buldng energy consumpton and urban desgn. (M) • need laboratory and cFD/Les studes wth structures that more closely resemble ctes than earler dealzed, homogenous arrays to nform model development for urban RsL turbulence. (M) • need further work on a smple unversal UHI model for appled users. (L) TOOLS • need to develop tools to allow models to be able to accommodate the wde dfferences n data avalablty dependng on the applcaton from

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156 156 WHen WeAtHeR MAtteRs research to operatonal stuaton e.g., n field research studes, extensve wnd observatons may be avalable (and detaled buldng morphology), but for emergency response stuatons only mnmal nputs may be avalable (e.g., wnds from the nearest arport, no 3-D buldng data). (H) • need to develop desgns for hot ctes whch promote shadng and ventlaton wthout compromsng ar qualty and natural lghtng. (H) • need to encourage development of actve smulaton tools (e.g. www. susdesgn.com/tools.php) through communty partcpaton (e.g. forums, blogs, wks). (H) • need to develop tools that allow competng and unntended mpacts of proposed sustanable desgn to be assessed (e.g., wll urban greenng reduce temperatures but ncrease humdty, resultng n no net ncrease n comfort levels?) (H) • need to develop tools that allow assessment of the best, or rank- ng of, socal, economc and envronmental decsons for urban clmate management (e.g., urban greenng vs. repavng roads and pavements wth hgh(er) albedo vs. low‐emssvty materals vs lmtng the contrbuton of anthropogenc heat; nvestment n expensve mult‐functonal solutons (e.g., vegetated roofs) vs. cheaper, sngle benefit solutons such as cool roofs). (H) • need to make use of spatal and temporal estmaton of transport emssons through vehcle fleet efficences and traffic data. (M) • need to solve techncal challenges such as mosture seepage n veg- etated roofs, and hazards to street trees (e.g., pests, new pathologes, sol qualty, compacton, dranage, frequent dsturbances from utlty trenches and excessve pavng). (M) • need to determne how to lnk the beneficares of urban clmate nterventons wth the costs of mplementng them. (M) EDUCATION • need to ensure wdespread educaton of the meteorologcal com- munty of the needs for plannng and managng ctes of all szes n as sustanable a manner as possble. (H) • need to encourage communcaton whch crosses tradtonal scen- tfic dscplne and spatal scales (e.g.: http://www.conservatoneconomy. net; http://www.sustanable-buldngs.org/ndex.php). (H) • need to mprove publc educaton and communcaton of heat/health percepton through use of smple language and communty access. (H)

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APPenDIX A 157 • need for collaboraton wth stakeholders n the wdespread develop- ment of heat/health warnng systems. (H) • need to communcate through conventonal publcatons and to use current (and evolvng) electronc meda to allow accessblty wth depth of content that s up-to date. (M)

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