7.3. Site parameters¶
A wide range of parameters can be set to characterise each grid in your study area. The following explains what things you should consider as you decide on the amount of effort needs to be spent on each fo these. Somed data can be obtained from literature and others are very site specifice. Dpending on your goal for applying the model you may want to spend more or less effort ensuring the parameters values are good/reasonable/OK for your site. A good starting point is to concentrate on the parameters that are initially most importnat and update the others once you have some initial runs.
7.3.1. Anthropogenic Heat¶
This varies significantly across a city and between cities.
This can be modelled offline (e.g. using LUCY, LQF) and then values supplied in the meterological input. The disadvantage of this is that the results are static (e.g. do not repond to temperature) but may allow for more sophisticated/detailed modeling of the values.
The offline models can be used to derive parameters for models within SUEWS (e.g. Ward and Grimmond 2017). This allows for the responses to conditions to be captured and then modelling for other conditions to be predicted.
Approaches
U approach (Ao et al. 2018)
V approach (Jarvi et al. 2011)
DASH approach (Capel-Timms et al. 2020)
LUCY/LQF approach (Allen et al. 2011, Lindberg et al. 2013, Gabey et al. 2019 )
GQF approach (Iamarino et al. 2012, Gabey et al. 2019)
References
Allen L, F Lindberg, CSB Grimmond 2011: Global to city scale model for anthropogenic heat flux, International J. of Climatology, 31, 1990-2005 10.1002/joc.2210
Ao Xiangyu, CSB Grimmond, HC Ward, AM Gabey, Jianguo Tan, Xiuqun Yang, Dongwei Liu, Xing Zhi, Hongya Liu, Ning Zhang Evaluation of the Surface Urban Energy and Water balance Scheme (SUEWS) at a dense urban site in Shanghai: Sensitivity to anthropogenic heat and irrigation J Hydrometeorology 19, 1983–2005,https://doi.org/10.1175/JHM-D-18-0057.1
Capel-Timms I, ST Smith, T Sun, S Grimmond Dynamic Anthropogenic activitieS impacting Heat emissions (DASH v1.0): Development and evaluation. In reivew
Gabey A, S Grimmond, I Capel-Timms 2019: Anthropogenic Heat Flux: advisable spatial resolutions when input data are scarce Theoretical and Applied Climatology 135 (1-2), 791-807 https://doi.org/10.1007/s00704-018-2367-y
Iamarino M, Beevers S, CSB Grimmond 2012: High Resolution (Space, Time) Anthropogenic Heat Emissions: London 1970-2025 International J. of Climatology 32, 1754-1767 10.1002/joc.2390
Järvi L, CSB Grimmond, A Christen 2011: The Surface Urban Energy and Water Balance Scheme (SUEWS): Evaluation in Vancouver and Los Angeles. J. of Hydrology, 411, 219-237 10.1016/j.jhydrol.2011.10.001
Lindberg F, CSB Grimmond, N Yogeswaran, S Kotthaus, L Allen 2013: Impact of city changes and weather on anthropogenic heat flux in Europe 1995-2015 Urban Climate,4, 1–15 10.1016/j.uclim.2013.03.002
Ward HC, S Grimmond 2017: Using biophysical modelling to assess the impact of various scenarios on summertime urban climate across Greater London Landscape and Urban Planning 165, 142–161, https://doi.org/10.1016/j.landurbplan.2017.04.001
7.3.2. Conductances¶
For urban areas, at the moement, we recommend the values that the model come with. However, for areas which are largely vegetated we recommend that other values are used. Omidvar et al. (2020) provides values for a range of different vegetation types.
How to determine your own values?
if you have observations for a long period (e.g. changing phenology) then you can calculate your own values. The following papers explain how:
Omdivar et al. (2020) - there are Jupyter Notebooks with Python code for many model parameters *start here*
`Ward et al. (2016) <Ward2016>
`Grimmond and Oke (1991) <G091>
7.3.3. Materials¶
For each material type there are different characteristics needed for the radiative, conductive and water behaviour.
¶ Type
Comment
Height
for larger roughness elements this is needed
Albedo important
This changes with phenology
Emissivity
Surface water storage capacity
amount of water that is intercepted before drainage occurs
Runoff/drainge of water from the surface
drainage rate after interception water storage is full
Storage Heat
Choice from three sub-models (OHM, AnOHM, ESTM) parameters needed vary with which is used
LAI/Phenology important
for vegetation it is necessary to capture the seasonal response of the vegetation.
Infiltration rate
does water pond on the surface or drain into the soil?
Soil
soil density, hydraulid conducitivity, depth,
How to determine your own values?
If you have observations for a long period (e.g. changing phenology) then you can calculate your own values. The following paper explains how:
Omdivar et al. (2020) - there are Jupyter Notebooks with Python code for many model parameters *start here*
7.3.4. Function¶
Does day light savings occur?
Type |
Comment |
---|---|
Energy Use |
When do people do things on work days? non-work days? |
External Water use |
garden irrigation, car cleaning, street cleaning, dust suppression,automatic or manual, flood irrigation to maintain a soil mositure content |
Snow clearing |
when does this occur? what is the prioriy order for a region (e.g. major vs minor roads) |
Population density |
day time densities (work, school relate)(Night - census where people live); DASH model allows fopoy dynamic occupancy (Capel-Timms et al. 2020) |
References
Capel-Timms I, ST Smith, T Sun, S Grimmond Dynamic Anthropogenic activitieS impacting Heat emissions (DASH v1.0): Development and evaluation. In reivew
7.3.5. Water within Grid¶
How does water move between areas?
Does the water from the roof all go in to drains or does some go on to grass?
All surfaces can be set to move water fronn one land cover to another - the constraint is that is it must add up to 100%
this will influence the soil moisture available (or not) to plants
does irrgation all go to vegetation or does flow to the roads if too wet
7.3.6. All¶
all the different characteristic types need to be considered
Tip
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