Assessing The Impact of LULCC on The Greater Phoenix Area Matei Georgescu Center for Environmental Prediction – Rutgers University The Fourth Symposium on Southwest Hydrometeorology Tucson, Arizona September 20-21, 2007

Topic Outline Introduction/Scientific Question Method of Investigation/Numerical Modeling Impact of Hypothetical LULCC over Greater Phoenix area Assessment of 30 years of LULCC over Greater Phoenix area Concluding Remarks and Future Work Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Growth of Recorded Subdivisions in Maricopa County ( ) Source: Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Urban Population Explosion Maricopa & Pinal Counties Total of Major National Urban Areas (2000 Population Over 1 Million) YearPopulationAnnual Growth RatePopulation Annual Growth Rate ,236 20,439, ,5334.4%27,316,2482.9% ,7069.3%34,429,9022.3% ,0515.1%44,613,8092.6% ,0342.2%48,677,9060.9% ,9615.7%59,922,4302.1% ,1836.8%76,934,1422.5% 19701,035,4383.6%91,258,4481.7% 19801,599,9704.4%99,239,0370.8% 19902,238,4803.4%111,908,8091.2% 20003,251,8763.8%127,353,5341.3% 100 Year 4.9% 1.8% 50 Year 4.4% 1.5% Source: Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Scientific Question Can we quantify the impacts of LULCC on local and regional weather and climate? What can we say about specific land-atmosphere interactions and possible feedbacks controlling these impacts? With expansion expected to occur for at least the next 50 years what consequences may be expected? As sprawl continues in the Greater Phoenix area, can we use lessons learned from this case study to mitigate effects from other rapidly urbanizing cities in arid areas (e.g., Las Vegas, Riyadh)? Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

38 Vertical Levels with 12 levels in the first 1500 m. RAMS Convective Parameterization: Kain-Fritsch. Interactive Soil and Vegetation Model (LEAF II). Initial Surface Boundary Condition: NARR Reanalysis Soil Moisture/Temperature of corresponding year. Nudging at lateral boundaries with 6- hr NARR data. RAMS [v 4.3] nested grid domain configuration Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Dominant LULC representation for fine grid employing circa 2001 (a), circa 1992 (b), circa 1973 (c) landscape, and a hypothetical land cover scenario (i.e., pre-1900) with anthropogenic influence removed (d). Fine grid LULC representation (a) (c) (b) (d) urban irr. agriculture shrubland Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Impact of Hypothetical LULCC over Greater Phoenix area Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Summary of experiments Summary of all 12 experiments performed. For each experiment, the analysis time consists of the period lasting from July 1, 12Z through July 31, 12Z. ** denotes experiment used as Control simulation which was validated against observations. LULC Year from which Initial and Boundary Conditions were used to force RAMS WET YearsDRY Years NLCD **1994 Pre- Settlement NLCD Pre- Settlement NLCD Pre- Settlement Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Comparison to Observations Observed three-hourly 1.5 meter air temperatures (black) and RAMS simulated 2-meter temperatures from the control run simulation (red) during the period July 1st -12Z to July 31st -12Z, Units are in [°C]. The time series represent temperatures averaged over five stations: (1) Sky Harbor International Airport, (2) Phoenix Encanto, (3) Phoenix Greenway, (4) Waddell, and (5) Maricopa Agricultural Station. Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL observations simulation Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Comparison to Observations Mean monthly temperature comparison between RAMS-simulated control experiment and station-observations for July 1, 12Z - July 31, 12Z, Station July 1 12Z – July 31, 12Z [1990] Mean Temperatures [°C] ObservedSimulated Phoenix – Sky Harbor Phoenix - Encanto Phoenix - Greenway Waddell Maricopa Agricultural Station Regional Average Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

RAMS simulated ensemble differences (NLCD92 - Pre-Settlement) in (a) first atmospheric level [24.1 m] air temperature [°C] and (b) dew point [°C], for the WET years; (c) first atmospheric level [24.1 m] air temperature [°C] and (d) dew point [°C], for the DRY years. Each calculation is for the analysis period: July 1, 12Z – July 31, 12Z. Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL (a) (b) (c)(d) TemperatureDew-point Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

RAMS simulated ensemble differences (NLCD92 - Pre-Settlement) in (a) total accumulated precipitation [mm] for all 3 WET years; (b) total accumulated precipitation [mm] for all 3 DRY years; Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL (a) (b) Precipitation Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

RAMS simulated ensemble member differences (NLCD92 - Pre-Settlement) in total accumulated precipitation [mm] for (a) 1994, (b) 1989, and (c) (a) (b)(c) Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL Precipitation Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Sensitivity of Summer Climate to Land Cover Change over the Greater Phoenix, AZ, Region (2007), Submitted to GRL (a) domain-averaged [lat: 33 to 34/lon: to ] vertical profile of equivalent potential temperature difference (NLCD92 - Pre-Settlement) for selected DRY year cases; (b) as (a), but averaged over each DRY year simulation for the analysis period: July 1, 12Z – July 31, 12Z. (a)(b) Equivalent Potential Temperature Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

RAMS simulated ensemble differences (NLCD01 minus NLCD73) in (a) first atmospheric level [24.1 m] air temperature [°C] and (b) dew point [°C], for all three WET years; (c) first atmospheric level [24.1 m] air temperature [°C] and (d) dew point [°C], for all three DRY years. Each calculation is for the analysis period: July 1, 12Z – July 31, 12Z. TemperatureDew-point (a) (c) (b) (d) Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

RAMS simulated ensemble differences (NLCD01 minus NLCD73) in surface sensible heat flux (a) for all three WET years, and (b) all three DRY years. RAMS simulated ensemble differences (NLCD01 minus NLCD73) in surface latent heat flux (c) for all three WET years and (d) all three DRY years. Each calculation is for the analysis period: July 1, 12Z – July 31, 12Z. All units expressed in W m -2. (a) (c) (b) (d) Sensible Heat FluxLatent Heat Flux Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area

Concluding Remarks/Future Work Offsetting contributions of irrigated agriculture and urbanization (in a regionally-averaged sense) are specified. Greater-Phoenix region induced impact on precipitation is noted during particular atmospheric regime. Preliminary assessment of 30 years of LULCC over Greater Phoenix indicates warmer and drier climate. What does the future hold in terms of continued growth rate and continued landscape alteration? Source: Georgescu Assessing The Impact of LULCC on The Greater Phoenix Area