The EPiCC Vancouver Experiment : How do urban vegetation - PowerPoint PPT Presentation

The EPiCC Vancouver Experiment : How do urban vegetation characteristics and garden irrigation control the local scale energy balance? Andreas Christen (1) , B. Crawford (1) , N. Goodwin (2,5) , R. Tooke (2) , N. Coops (2) , C.S.B. Grimmond (3) , T. R. Oke (1) , and J. A. Voogt (4) (1) University of British Columbia, Department of Geography, Atmospheric Science Program,. (2) University of British Columbia, Department of Forest Resource Management, Vancouver, Canada (3) King’s College London, Department of Geography, London, UK (4) University of Western Ontario, Department of Geography, London, Canada (5) Department of Natural Resources, Queensland Government, Brisbane, Australia.

Motivation for this study Environmental Prediction in Canadian Cities (EPiCC) network: Include an urban canopy parameterization (UCP) in Canada’s weather forecasting system. Contribute to models that will support water conservation and support sustainable design in Canadian cities. See also: Voogt et al., paper J.1.4 (same conference, Tuesday, 9:15, Room 124A)

Urban Canopy Parameterizations (UCPs) Urban energy balance field studies: Plan area fractions Va92i Tu90u Me93 Va08s Ba02u3 Mo05 Sg94 Ba96 Lo01 Va92s Ba02u2 Mi95 Ba02u1 To98 Cc97 Ma01u Ch95 Va08o Ch92 Me03h Cc95 Ba02s1 Me03m Ac94 Ac93 Me03l Va83 Bm01 Sa91u Oa03r

Urban Canopy Parameterizations (UCPs) Urban energy balance field studies: Plan area fractions Traditional SVAT schemes work Va92i Tu90u well here Me93 Va08s Ba02u3 Mo05 Sg94 Ba96 Lo01 Va92s Ba02u2 Mi95 Ba02u1 To98 Cc97 Ma01u Ch95 Va08o Ch92 Me03h Cc95 Ba02s1 Me03m Ac94 Ac93 Me03l Va83 Bm01 Sa91u Oa03r

Urban Canopy Parameterizations (UCPs) Urban energy balance field studies: Plan area fractions UCPs have been tested here, and work well Traditional SVAT schemes work Va92i Tu90u well here Me93 Va08s Ba02u3 Mo05 Sg94 Ba96 Lo01 Va92s Ba02u2 Mi95 Ba02u1 To98 Cc97 Ma01u Ch95 Va08o Ch92 Me03h Cc95 Ba02s1 Me03m Ac94 Ac93 Me03l Va83 Bm01 Sa91u Oa03r

Urban Canopy Parameterizations (UCPs) Urban energy balance field studies: Plan area fractions UCPs combined with SVATs do not work so well here, or have not been tested. UCPs have been tested here, and work well Traditional SVAT schemes work Va92i Tu90u well here Me93 Va08s Ba02u3 Mo05 Sg94 Ba96 Lo01 Va92s Ba02u2 Mi95 Ba02u1 To98 Cc97 Ma01u Ch95 Va08o Ch92 Me03h Cc95 Ba02s1 Me03m Ac94 Ac93 Me03l Va83 Bm01 Sa91u Oa03r

The Vancouver Validation Experiment Simultaneously operated energy balance and hydrology sites in two contrasting neighborhoods in the City of Vancouver, BC, Canada and at a rural reference site to address the questions:

The Vancouver Validation Experiment Simultaneously operated energy balance and hydrology sites in two contrasting neighborhoods in the City of Vancouver, BC, Canada and at a rural reference site to address the questions: What is the role of anthropogenic water release associated with irrigation / sprinkling of urban green-space in the urban energy balance?

The Vancouver Validation Experiment Simultaneously operated energy balance and hydrology sites in two contrasting neighborhoods in the City of Vancouver, BC, Canada and at a rural reference site to address the questions: What is the role of anthropogenic water release associated with irrigation / sprinkling of urban green-space in the urban energy balance? Are the wet-dry contrasts of adjacent urban surfaces (that result from irrigation and paving) boosting evaporation in a non-linear fashion?

Study Sites Vancouver, BC, Canada Vancouver-Oakridge Vancouver-Sunset Building and population 9 Bldg. / ha 19 Bldg. / ha density 30 Inh. / ha 60 Inh. / ha Irrigation 61 % automatic 1 % automatic 34 % manual 79 % manual 5 % none 20 % none Vegetation λ v = 56% λ v = 44% High amount of tall trees Street trees, but very few on streets and private lots trees on private lots.

Eddy covariance Fluxes of sensible heat, latent heat (evapotranspiration) Net all-wave radiation

Soil hydrology observations 8 sites

Surface Wetness CR10 X Logger Soil moisture -5cm Soil Temperature -5cm

Rural reference site ‘Westham Island’ with non-irrigated, non-managed grassland

Q E / Q* Summer 2008

Ensemble Energy Balance Ensemble diurnal course, Aug. 11 to 17, 2008

Urban-rural differences Ensemble diurnal course, Aug. 11 to 17, 2008

The ‘tiling’ approach for urban surfaces Summation of Q E based on fraction Q E = λ v Q E v + (1 − λ v ) Q E i

The ‘tiling’ approach for urban surfaces Average daily totals for Aug. 11 to 17, 2008 Summation of Q E based on fraction Rural 5 Q E = λ v Q E v + (1 − λ v ) Q E i 4 Measured Oakridge Q E (MJ d -1 m -2 ) s n o i t c a r 3 f Measured Sunset g n i m m u s y b 2 d e t c i d e r P 1 0 0 0.2 0.4 0.6 0.8 1 Q Ei = 0 Vegetation fraction λ v

Is a summation of fractions adequate? β = Q H / Q E is greatly overestimated when summing the urban and rural fractions. β calc = 1 + β rural − 1 λ v Hourly data from Aug 13, 14, 17, and 18 2008 (days with irrigation permitted)

Daily average water consumption per home Lawn sprinkling not permitted Lawn sprinkling permitted 3,000 Water consumption ( l day -1 home -1 ) 2,807 2,760 2,625 2,405 2,250 1,875 1,777 1,500 1,438 1,413 1,340 1,125 750 375 0 Mon Tue Wed Thu Fri Sat Sun Week August 11 to 17, 2008

Partitioning water consumption Household use Lawn sprinkling fraction 3,000 Water consumption ( l day -1 home -1 ) 1,410 1,363 2,625 1,008 2,250 1,875 380 1,500 1,438 1,413 1,397 1,397 1,397 1,397 1,340 1,125 750 375 0 Mon Tue Wed Thu Fri Sat Sun Week August 11 to 17, 2008

The water balance for Vancouver Oakridge Measured by rain gauge Measured by EC Aug 11 to 17, 2008 p E 1.57 mm d -1 0.00 mm d -1 Measured by water meters 1.16 mm d -1 I Residual term Δ r 0.12 mm d -1 Estimated via CO 2 flux F < 0.01 mm d -1 Measured by TDR Δ S - 0.52 mm d -1 p + F + I = E + ∆ r + ∆ S

Key points Vegetation fraction significantly controls the partitioning of turbulent fluxes in the urban energy balance. Acknowledgments: Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), NSERC, BC hydro, the City of Vancouver, all home owners who agreed to install meters and sensors on their lawns, technical contributions by Jonathan Bau, Kate Liss, Rick Ketler, Zoran Nesic and Chad Siemens.

Key points Vegetation fraction significantly controls the partitioning of turbulent fluxes in the urban energy balance. However, a simple summation (‘tiling’) of a ‘rural’ vegetated (SVAT) and a dry ‘urban’ impervious fraction (UCP) is was shown to be insufficient to model the summertime energy balance of the study area. Acknowledgments: Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), NSERC, BC hydro, the City of Vancouver, all home owners who agreed to install meters and sensors on their lawns, technical contributions by Jonathan Bau, Kate Liss, Rick Ketler, Zoran Nesic and Chad Siemens.

Key points Vegetation fraction significantly controls the partitioning of turbulent fluxes in the urban energy balance. However, a simple summation (‘tiling’) of a ‘rural’ vegetated (SVAT) and a dry ‘urban’ impervious fraction (UCP) is was shown to be insufficient to model the summertime energy balance of the study area. Lawn irrigation was the most important water input during the analyzed week. Hence any appropriate modeling of the urban energy balance must take anthropogenic water input through lawn irrigation (and potentially advective effects) into account. Acknowledgments: Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), NSERC, BC hydro, the City of Vancouver, all home owners who agreed to install meters and sensors on their lawns, technical contributions by Jonathan Bau, Kate Liss, Rick Ketler, Zoran Nesic and Chad Siemens.