Observational and Modeling Study of Observational and Modeling Study of Urbanization vs. Global Warming Impacts Urbanization vs. Global Warming Impacts

on SoCAB and SFBA Climateon SoCAB and SFBA Climate

Bereket Lebassi HabtezionBereket Lebassi HabtezionPh.D. CandidatePh.D. Candidate

Department of Mechanical EngineeringDepartment of Mechanical EngineeringSanta Clara UniversitySanta Clara University

Prof. Jorge GonzalezProf. Jorge GonzalezAdvisorAdvisor

Department of Mechanical EngineeringDepartment of Mechanical EngineeringCity College Of New YorkCity College Of New York

Presented at Santa Clara University Presented at Santa Clara University Dissertation defenseDissertation defense

onon

9 June 20109 June 2010

Outline

1. Background and Hypothesis

2. Observational Study

• SFBA and SoCAB analysis

• Impacts on Energy

3. Simulation Setup

• Grid Configuration

• Land Use input

• Anthropogenic heating

4. Results & Validation

• GHG impacts

• Urbanization impacts

5. Conclusion

Motivation 1: GHG Global-WarmingMotivation 1: GHG Global-Warming

From NASA RESEARCH NEWS (2006), group led by James Hansen, GISS, NYC

• Earth has warmed approximately 0.2 oC/decade for past 30 years, with max

warming after 1970

• Land temps has warmed faster than SSTs

Motivation 2: Interaction of coastal Motivation 2: Interaction of coastal climate influencesclimate influences

• GlobalGlobal– Sea surface temps (SSTs) Sea surface temps (SSTs) – Ocean currentsOcean currents– General Circulation (GC) pressure systemsGeneral Circulation (GC) pressure systems

• MesoscaleMesoscale– Sea/land breezesSea/land breezes– Mt/valley breezesMt/valley breezes– Ocean upwellingOcean upwelling– Land-use &/or Land-cover (LULC) changesLand-use &/or Land-cover (LULC) changes– Urban heat islands (UHIs)Urban heat islands (UHIs)

Earlier studies have related climate-change to Earlier studies have related climate-change to increased increased (*=CA studies; modeling studies (*=CA studies; modeling studies in yellow):in yellow):

• SSTs, evap rate:SSTs, evap rate: *Goodridge ‘91, Karl et al. ‘93 *Goodridge ‘91, Karl et al. ‘93

• Cloud cover changes:Cloud cover changes: * *Nemani et al. ’01Nemani et al. ’01

• Upwelling:Upwelling: * *Bakun ‘90,Bakun ‘90, **SnyderSnyder et al. ‘03 et al. ‘03; ; McGregor et al. McGregor et al.

‘07‘07

• Anthropogenic land cover conversions:Anthropogenic land cover conversions: Pielke et al. ’07Pielke et al. ’07,,

Chase et al. ‘00; Mintz ‘84; Zhang ‘97Chase et al. ‘00; Mintz ‘84; Zhang ‘97

• Irrigation:Irrigation: *Christy et al. ’06, *Christy et al. ’06, Lobell et al. ’06, *Kueppers et Lobell et al. ’06, *Kueppers et

al. ’07al. ’07,, *Bonfils et al. ’07 *Bonfils et al. ’07

• GHGs:GHGs: *Duffy et al. ’06, *Duffy et al. ’06, Walters et al. ’07, Cayan et al. ‘08Walters et al. ’07, Cayan et al. ‘08

• UHIs:UHIs: Ladochy et al. ’07 Ladochy et al. ’07

Research questions: the relative Research questions: the relative contributions to observed contributions to observed

temperature-trends in temperature-trends in coastal-urban areas from coastal-urban areas from

GHG-warming &/or LCLU-changes?GHG-warming &/or LCLU-changes?

1. In urban coastal regions, what temperature-change

is due to each of the following:

• GHG-induced global climate-change

• urbanization (i.e., LULC-changes)

2. How do these temperature-changes influence

coastal-flows

a.a. GHG WARMING/LULC GHG WARMING/LULC and/or and/or b.b. INCREASED INCREASED INLAND WARMINGINLAND WARMING

INCREASED HORIZONTAL INCREASED HORIZONTAL T- & p-GRADIENTST- & p-GRADIENTS

(COAST TO INLAND)(COAST TO INLAND)

INCREASED INCREASED SEA BREEZE SEA BREEZE FREQ, INTENSITY, FREQ, INTENSITY,

PENETRATION, &/OR DURATION PENETRATION, &/OR DURATION

COASTAL REGIONS DOMINATED BY SEA COASTAL REGIONS DOMINATED BY SEA BREEZES SHOULD THUS BREEZES SHOULD THUS COOLCOOL DURING DURING SUMMER DAYTIMESUMMER DAYTIME PERIODS PERIODS

Current Hypothesis: Observed Calif Current Hypothesis: Observed Calif temp trends resulted fromtemp trends resulted from

DATADATA• NCDC NCDC DAILY MAX & MIN 2-METER DAILY MAX & MIN 2-METER

TEMPSTEMPS FROM 273 CALIF SITES (see FROM 273 CALIF SITES (see map below) FROM 1948-2005map below) FROM 1948-2005

• NCDC NCDC MEAN MONTHLY GRIDDED MEAN MONTHLY GRIDDED SSTsSSTs– INTERNATIONAL COMPREHENSIVE 0CEAN-INTERNATIONAL COMPREHENSIVE 0CEAN-

ATM DATA SET (ICOADS)ATM DATA SET (ICOADS)– 2 OR 1 DEG HORIZ RESOLUTION2 OR 1 DEG HORIZ RESOLUTION

• SCU SCU DOWNSCALED REGIONAL DOWNSCALED REGIONAL CLIMATE CHANGE MODELING CLIMATE CHANGE MODELING RESULTSRESULTS FOR CALIF (10 KM FOR CALIF (10 KM RESOLUTION) FOR 21RESOLUTION) FOR 21STST CENTURY (see CENTURY (see same map below)same map below)

ANALYSESANALYSES• Only data from Only data from 1970-2005 (due to its 1970-2005 (due to its

accelerated warming) accelerated warming) were usedwere used

• Annual & summer (JJA) Annual & summer (JJA) warming/cooling trendswarming/cooling trends calculated (calculated (00C/decade) for SST, TC/decade) for SST, Tmaxmax, T, Tminmin

• Spatial distributionsSpatial distributions of JJA T of JJA Tmaxmax trends plotted for trends plotted for– South Coast Air Basin (SoCAB)South Coast Air Basin (SoCAB)– SFBA and Central Valley (CV)SFBA and Central Valley (CV)

• JJA land-sea JJA land-sea T-gradientT-gradient (as surrogate for (as surrogate for

p-gradient) trends calculated fromp-gradient) trends calculated from– mean monthly SSTs mean monthly SSTs

– 2-m land T2-m land Tmaxmax values values

SCU (Maurer 2007) statistically 10-km downscaled 1950-SCU (Maurer 2007) statistically 10-km downscaled 1950-2000 modeled JJA temps (2000 modeled JJA temps (00C) show total warming rates C) show total warming rates

that decrease to coast (dots are Calif NCDC sites & that decrease to coast (dots are Calif NCDC sites & boxes are study sub-areas)boxes are study sub-areas)

Result 1: Lebassi et al. (2009) J. of Climate Result 1: Lebassi et al. (2009) J. of Climate

Observed 1970-2005 CA JJA max-TObserved 1970-2005 CA JJA max-Temp emp ((00C/decade)C/decade) trends in SFBA & SoCAB show concurrent:trends in SFBA & SoCAB show concurrent:

> low-elev coastal-cooling & > high elev & inland-> low-elev coastal-cooling & > high elev & inland-warmingwarming > signif levels: solid circles >99% & open circles > signif levels: solid circles >99% & open circles <90%)<90%)

Results 2: Same for SFBA & Central Results 2: Same for SFBA & Central ValleyValleyCOOLING AREAS: COOLING AREAS: MARIN LOWLANDS, MONTEREY, SANTA CLARA MARIN LOWLANDS, MONTEREY, SANTA CLARA V., V., LIVERMORE V., WESTERN HALF OF SACRAMENTO V. LIVERMORE V., WESTERN HALF OF SACRAMENTO V.

TTminmin (Curve b) (Curve b) increasing faster increasing faster than Tthan Tmaxmax (Curve (Curve c)c)

Results 3: Temp. trends for all of California

Result 4: Combined SFBA & SoCAB 1970-2005 summer trends

(oC decade-1) of Tmax (Curves c)Inland Tmax warmingwarming sites

Coastal Tmax coolingcooling sites

(a)

(b)

(c)

(d)

• p-increases (up to 0.34 hPa decade-1) in Pacific High

• p-decreases (up to -0.8 hPa decade-1) in Calif- Nevada thermal Low

• p-gradient trend in next slide

Result 5: Average JJA 1.4-deg ERA40-reanalysis SLP trends Result 5: Average JJA 1.4-deg ERA40-reanalysis SLP trends (hPa/decade) at 11 LT for 1970-2005(hPa/decade) at 11 LT for 1970-2005

• As Temp-grad is As Temp-grad is only a surrogate for p-only a surrogate for p-grad,…grad,…

• Arrow shows SLP-Arrow shows SLP-gradient calc. end-gradient calc. end-pointspoints

• Plus & minus are Plus & minus are High- & Low-pressure High- & Low-pressure centers, respectively.centers, respectively.

+

-

+

Result 6: Trend in ocean-land summer SLP-gradient Result 6: Trend in ocean-land summer SLP-gradient

(hPa 100-km(hPa 100-km-1-1 decade decade-1-1) at 11 LT at end-points in previous ) at 11 LT at end-points in previous slideslide

Results show: p-gradient increases in both areas increased sea breeze

Result 7: Implications of max-Temp trend on Result 7: Implications of max-Temp trend on Calif Calif energy-usageenergy-usage

Lebassi et. al (2010) J. of Solar Energy and EngineeringLebassi et. al (2010) J. of Solar Energy and Engineering

(a) Cooling (a) Cooling Degree Day (CDD) Degree Day (CDD) trend: trend: upwardupward due due to GHG warming to GHG warming More energy for More energy for coolingcooling

(b) Heating (b) Heating Degree Day (HDD)Degree Day (HDD) trend: downward due you to GHG ue you to GHG warming warming Less energy for Less energy for heatingheating

SUMMARY 1: SUMMARY 1: OF OBS STUDYOF OBS STUDY• SUMMER DAYTIME MAX-TEMPSSUMMER DAYTIME MAX-TEMPS HAVE HAVE

– COOLEDCOOLED IN LOW-ELEVATION IN LOW-ELEVATION COASTALCOASTAL AREAS AREAS

– WARMEDWARMED IN INLAND AREAS IN INLAND AREAS

• PREVIOUS STUDIES DREW WRONG PREVIOUS STUDIES DREW WRONG CONCLUSIONS B/CCONCLUSIONS B/C– They did not separate summer vs. winter, They did not separate summer vs. winter,

day vs. night, day vs. night, &/or&/or inland vs. coastal inland vs. coastal

– Therefore, their TTherefore, their Tmaxmax were wrong and thus were wrong and thus their Ttheir Taveave & DTRs were also & DTRs were also contaminatedcontaminated

Modeling EffortModeling Effort

Introduction to Introduction to Regional Atmospheric Modeling System (RAMS)Regional Atmospheric Modeling System (RAMS)

RAMS RANS (non-transformed) EquationsRAMS RANS (non-transformed) Equations

R

ililh

ilh

ilh

ilililil

t

θ

z

θK

zy

θK

yx

θK

x-

z

θw

y

θv

x

θu

t

θ

SS

nnh

nh

nh

nnnn

t

r

z

rK

zy

rK

yx

rK

x-

z

rw

y

rv

x

ru

t

r

z

wK

zy

wK

yx

wK

xθ

gθ-

z

πθ-

z

ww

y

wv

x

wu

t

w

z

vK

zy

vK

yx

vK

xfu

y

πθ-

z

vw

y

vv

x

vu

t

v

z

uK

zy

uK

yx

uK

xfv

x

πθ-

z

uw

y

uv

x

uu

t

u

mmm0

v

mmm

mmm

Momentum eqs for u, v & w

Thermodynamic Eq for ice-liquid water potential-temp

Water Species (n-species, e.g. vapor, ice, snow, …)

(1)

(2)

(3)

Latent heat & RFD

Sources & sinks via phase changes

Local ∆ = Advection + p-grad + Coriolis + Turbulent Diffusion

Km, h: eddy diffusivity coef. for momentum & heat.

z

wθρ

y

vθρ

x

uθρ

θρc

Rπ

t

π 000000

00v

0

pd cR

vil pT //1000

vdTRp

(4)

(5)

(6)

(7)

Pressure Eq (in terms of π)

Ideal Gas Law for density

Poisson eq for Tv

pd cRpT /1000// Exner function π, for pressure

πππ 0

In summary:

• Prog Eqs for u, v, w, өil, rn, π′• Diag Eqs for π, ρ, p, Tv

Vertical Diffusion Coef KVertical Diffusion Coef Km,h,em,h,e via TKE (e) via TKE (e)

)z(z

κ1

)zκ(z

o

o

222 w'v'u2

1e

εPPz

eK

zy

eK

yx

eK

x-

z

ew

y

ev

x

eu

t

ebseee

,x

v

x

uKP

22

ms

,z

θK

θ

gP v

hb

3/2

e

eaε

2eSK

2eSK

2eSK

ee

hh

mm

Shear Production Buoyancy Molec Dissipation

Sm,h,e are f(Ri) l is mixing length

dze

dzez0.1 H

0

H

0

Vertical Boundary ConditionsVertical Boundary Conditions

z= H (model top) = 18.8 kmz= H (model top) = 18.8 km Rigid lid, with Rayleigh friction layer of 4 kmRigid lid, with Rayleigh friction layer of 4 km w = 0w = 0

z= h (SBL top) = 50 m z= h (SBL top) = 50 m Continuity of fluxes, gradients, & profilesContinuity of fluxes, gradients, & profiles

z= 0 (sfc) z= 0 (sfc) Sfc energy balance Eq in LEAF3Sfc energy balance Eq in LEAF3 No slip BC: V = 0No slip BC: V = 0

z=Hz=Hss (bottom soil layer) = 1 m (bottom soil layer) = 1 m

Constant temperature from large scale modelConstant temperature from large scale model

Sfc BC for T(t): RAMS uses LEAF-3 “big leaf” model to solve Sfc BC for T(t): RAMS uses LEAF-3 “big leaf” model to solve sfc energy balance at each sfc-type, sfc energy balance at each sfc-type,

e.g., for all-urban sfcs (no veg or evaporation)e.g., for all-urban sfcs (no veg or evaporation)

A

g

sspauugglsu

uuu Q

zCuCTTRR

tzC

**

44)1(

Terms on RHS of eq (L to R): • ↓ solar rad absorbed at sfc• ↓ IR rad from atm absorbed at sfc• ↑ IR rad from sfc to atm• ↑ IR rad from urban sfc

Note: rad terms come from complex rad-transfer model • convective heat to atm [where ( )* quantities come from SBL-Eq ]• ground heat to atm (where өs comes prog soil temp Eq)• anthro heat to atm. (specified, in slide below)

Finally: sum of RHS terms yields trend of building-canopy temp θu, which when added to past-value gives current-value.

Class α ε FV HV (m)

Short grass 0.21 0.95 0.75 0.3

Low-intensity urban 0.28 0.90 0.42 6.0

High-intensity urban 0.28 0.90 0.10 20.0

Parameter-values (needed as input in previous Eq) for different urban classes

where α Albedoε EmissivityFV Vegetation FractionHV Vegetation/building Height

Set up of Set up of RAMS simulations of SoCAB AreaRAMS simulations of SoCAB Area

5 years running average PDO (green) and Average Temperature (black) correlation for California coast

-2.5-2

-1.5

-1-0.5

00.5

1

1.52

2.5

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Tem

per

atu

re A

no

um

aly

Selected past (1966-70) & present (2001-2005) simulation-periods: have similar PDO- & temp-variations large-scale variability effects are

eliminated

Note: ENSO summer-impacts are mainly in winter in study-area

• Research goal:Research goal: separate-out effects of separate-out effects of urbanization & GHG urbanization & GHG warmingwarming

• on observed Lebassi et al. (2009) SoCAB JJA max-temp trends on observed Lebassi et al. (2009) SoCAB JJA max-temp trends • use RAMS to simulate these changes use RAMS to simulate these changes

• RAMS simulationsRAMS simulations• Runs 1 vs. 2:Runs 1 vs. 2:

• Research question: Research question: Effects of global climate-change?Effects of global climate-change?• Run 1: current Run 1: current

• urban LULC (NOAA 2002) at 30-m resolution urban LULC (NOAA 2002) at 30-m resolution • global-climate & SSTs for five JJA-periods (2001 to 2005)global-climate & SSTs for five JJA-periods (2001 to 2005)

• Run 2: usesRun 2: uses• Run 1 (Current 2002) LULCRun 1 (Current 2002) LULC• global climate & SSTs for five past JJA-periods (1966 to global climate & SSTs for five past JJA-periods (1966 to 1970) 1970)

• Runs 1 vs. 3:Runs 1 vs. 3: • Research question: Research question: Effects of urbanization? Effects of urbanization? • Run 1: one-year of Run 1 (2002)Run 1: one-year of Run 1 (2002)• Run 3: pre-urbanRun 3: pre-urban

• LULC: all urban turned to local dominant-class, i.e., LULC: all urban turned to local dominant-class, i.e., scrublandscrubland• over-estimate of max-urbanization effectsover-estimate of max-urbanization effects• 2002 JJA global-climate & SSTs2002 JJA global-climate & SSTs

Simulation Determination

•Model initializedModel initialized

• 0000 UTC = 17 LT0000 UTC = 17 LT

• 1 June of given year 1 June of given year

•12-hr spin up: 12-hr spin up: 11stst night night

•Large scale BCsLarge scale BCs

• every 6-hrevery 6-hr

• from gridded NCEP global-model outputfrom gridded NCEP global-model output

ICs and Large-scale BCs (FDDA)ICs and Large-scale BCs (FDDA)

> Arakawa-C> Arakawa-C staggered gridstaggered gridHoriz nested-grid Horiz nested-grid resolutionresolution

- Grid 1: Grid 1: 20 km20 km- Grid 2: Grid 2: 4 km4 km

• Vertical GridVertical Grid >> 49 levels to 31 km49 levels to 31 km ΔΔz = z = 40 m (near sfc)40 m (near sfc) 1.15 stretch-ratio 1.15 stretch-ratio ΔΔz =z = 1.2 km (aloft)1.2 km (aloft)

Grid ConfigurationGrid Configuration

Grid 2 (4 km): present (2002) LULC-classesGrid 2 (4 km): present (2002) LULC-classes• Lines: Lines: key topographic-heights (+ = key topographic-heights (+ = peaks) peaks)• Input:Input: 30-m NOAA C-CAP LULC 30-m NOAA C-CAP LULC RAMS’s Leaf-3 classifications RAMS’s Leaf-3 classifications• Output colors:Output colors: dominant class; parameter values as weighed dominant class; parameter values as weighed averagesaverages

• Veg:Veg: greens greens• Urban:Urban: browns browns

• Black squares:Black squares: METAR stations for RAMS evaluation METAR stations for RAMS evaluation

++

+ +

Model-Evaluation with Run-1 (Model-Evaluation with Run-1 (currentcurrent met & LU) met & LU) output: output:

June 1-10, 2002; averages of 12 SoCAB METAR June 1-10, 2002; averages of 12 SoCAB METAR sitessites

where: blue is obs & red is closest RAMS grid where: blue is obs & red is closest RAMS grid pointpoint

Mean wind speeds: both at 10-m Mean temps: both at 2-mMean wind speeds: both at 10-m Mean temps: both at 2-mmodel =3.1 m/s vs. obs = 2.9 m/s model = 20.2model =3.1 m/s vs. obs = 2.9 m/s model = 20.2ooC vs.C vs. obs = obs = 19.319.3ooCC

Model-Evaluation (cont.)Model-Evaluation (cont.)

Current-period evaluationCurrent-period evaluation(previous slide):(previous slide):

• Temp: rTemp: r22 = 0. 87 = 0. 87 (blue)(blue)• SpeedSpeed: r: r22 = 0.82 = 0.82 (red)(red)

Correlation (for part-b):Correlation (for part-b):rr22 = 0. 70 = 0. 70

Past-period evaluation:Past-period evaluation:• 1970 JJA-average 1970 JJA-average daily-daily-TTmaxmax

• average of 15 COOP-average of 15 COOP-sitessites• Model (red) minus Model (red) minus Obs (blue)Obs (blue)• TTmax max ave-diff = 0.7ave-diff = 0.7ooCC

aa

bb

cc

RAMS Results:RAMS Results: 19-m spatial-patterns 19-m spatial-patterns

in following orderin following order

Temp- and wind-results from Temp- and wind-results from – Run 1: current climate and current Run 1: current climate and current

urbanization urbanization – Run 2: past climate and current urbanizationRun 2: past climate and current urbanization– Run 1 minus Run 2Run 1 minus Run 2– Run 3: current climate and no-urbanizationRun 3: current climate and no-urbanization– Run 1 minus Run 3Run 1 minus Run 3

Large scale BC inputs into Large scale BC inputs into RAMSRAMS

(next 5 slides)(next 5 slides)

NCEP SLP: 17-LT JJA (5-yr Ave)• Orig. SLP-resolution: 2.5 deg

• Top R: Run-2 (P); Top L: Run 1 (N)• Lower: Run-1 minus Run-2 (N-P)• Box: area of p- grad calculation

Results: Location of H: not much change• Mag: diminished over most of ocean• Peak-decreases: over center of H• Increases found: N & S of decrease area• Max-decrease over Mx-coast (our D-2) due to expansion of Thermal- L over land

PastNow

N- PN- P

HL

HL

- -+

+

Present & Past 17-LT JJA-Ave NCEP 1000-hPa Present & Past 17-LT JJA-Ave NCEP 1000-hPa T(T(ooC)C)• Area is Area is black-boxblack-box sub-area of previous slide sub-area of previous slide • BC input to RAMS: BC input to RAMS: every 6-hrevery 6-hr for periods of Run-1(N) for periods of Run-1(N) && Run-2 (P) Run-2 (P)• White boxes:White boxes: D-1 & D-2 D-1 & D-2• Both results:Both results: Hot inland (H) & Cool ocean (C) Hot inland (H) & Cool ocean (C)• Comparison:Comparison: H & C centers: moved to SE H & C centers: moved to SE• Changes:Changes: best seen in best seen in next slidenext slide

NowNow PastPastC

H H

C

Left Slide: vertical section Left Slide: vertical section (from Fig. on right; topo not (from Fig. on right; topo not shown)shown)• Violet-line: land-areaViolet-line: land-area• Green line: D-1; White-line: D-Green line: D-1; White-line: D-22Results:Results: • Max warming: at 350-hPa or Max warming: at 350-hPa or 1.6km1.6km• Cooling: up to 980-hPa (= 400-Cooling: up to 980-hPa (= 400-m)m)

Right slide: horizontal sectionRight slide: horizontal section• Area is same as previous slide Area is same as previous slide • Boxes: again D-1 & D-2Boxes: again D-1 & D-2• Dash-line: z-section for slide at rightDash-line: z-section for slide at right

Results:Results: Inland warmingInland warming (+) & (+) & off-shore coolingoff-shore cooling (-) protrudes into D- (-) protrudes into D-22

Present minus PastPresent minus Past 17-LT JJA-Ave NCEP 1000-hPa 17-LT JJA-Ave NCEP 1000-hPa ΔT(T(ooC)C)

N - PN - P N - PN - P

--

+ +

Note:Note: cooling-area is b/t coast & center of H (to West) cooling-area is b/t coast & center of H (to West) and in the area of falling-SLP of previous slide and in the area of falling-SLP of previous slide (more (more

below)below)

T(oC)

ICOADS BC-SST: input to RAMS• Box is D-2• RAMS-interpolated D-1: JJA 5-yr ave. (constant for a given summer) • Top L: Run-1 (N) orig.-resolution: 1 deg• Top R: Run-2 (P) orig- resolution: 2 deg• Lower: Run-1 minus Run-2 SST (N-P)

Large-scale SST results:• NW-cooling in D-1 is a large-scale effect • max-warming in south

N- P

PastNow

T(oC)

RAMS GHG-WARMING RAMS GHG-WARMING RESULTS:RESULTS:

NEXT 8-SLIDESNEXT 8-SLIDES

12 LT 14 LT

16 LT

RAMS Run-1 (present) JJA-ave. D-1 T(oC) & V (barb = 1 m/s); Box is

D-2

Results: • Cool: ocean, coastal, & Mt. areas• Warm: inland• 12 LT: SB- & upslope-flows started • 14 LT: Both flows: more-developed• 16 LT: combined SB- & upslope- flows

Interpretation of Interpretation of sea-breeze sea-breeze wind-vector differences plotswind-vector differences plots

P

N

N-P

where:N = current wind-vector (red)P = past wind-vector (black)C-P = current minus past (white)

P

N

N-P

-P

-P

Retardation case: P > N, so N-P is in opposite dir (off-shore)

Acceleration case: N > P, so N-P is in their dir (on-shore)

14 LT14 LT12 LT12 LT

16 LT16 LT

RAMS Run-1 (present, prev. slide) minus Run-2 (past) JJA-Ave D-1 T(oC) & V (barb=0.4 m/s); Box is D-2Results: • Ocean warming < inland warming• 12 LT: coastal-cooling started; SB-change not evident in D-2 • 14 LT: coastal-cooling fills basin N-S & SB-change still not resolved in D-2• 16 LT: coastal-cooling reaches max & SB starts to weaken!!

D-2 JJA-Aver ∆T(oC) & ∆V (barb = 0.5 m s-1)

Results (relative to D-1): • More details & stronger temp & flow effects

• 12 LT: SB better defined & coastal-cooling is in 2-parts

• 14 LT: SB acceleration now visible & coastal- cooling is seen as stronger N of city

• 16 LT: SB starts to slow offshore, but is still accelerating over city • Peak coastal-cooling over 35-years of about 1.0 oC matches observed trend of 0.3 oC/decade • Dashed-line is for subsequent z-

section

14 LT14 LT

12 LT12 LT

16 LT16 LT

Two-tailed stat. sig. values for T, U, & VTwo-tailed stat. sig. values for T, U, & V

12 LT

14 LT

16 LT

• ∆ ∆TT:: coastal-cooling, SST-change, & inland-warming are mostly coastal-cooling, SST-change, & inland-warming are mostly significant at >99% (grey); lsignificant at >99% (grey); less-significantess-significant (<90%, yellow) results (<90%, yellow) results are due to cancellation of GHG-warming by increased marine-flow are due to cancellation of GHG-warming by increased marine-flow coolingcooling• ∆ ∆UU & ∆∆VV: Most changes also significant at 99%; less-significant : Most changes also significant at 99%; less-significant areas are over ocean at 12 LT when SB change is not strong & over areas are over ocean at 12 LT when SB change is not strong & over land at 14 LT when SB starts to weakenland at 14 LT when SB starts to weaken

TU

V

z-section at 33.85 N for z-section at 33.85 N for T(T(ooC) & (u, 100w) wind (m/s)C) & (u, 100w) wind (m/s)• Top RTop R Run-1 (Now): NCEP cold-area to 500- Run-1 (Now): NCEP cold-area to 500-m; warmest inland; inversion top 900-m & m; warmest inland; inversion top 900-m & base 50-mbase 50-m• Top LTop L Run-2 (Past): inversion top now 750-m Run-2 (Past): inversion top now 750-m & inversion-base at sfc& inversion-base at sfc• Bottom RBottom R Run-1 (N) minus Run 2 (P): Run-1 (N) minus Run 2 (P): > Present w-wind: up in cooling area & down > Present w-wind: up in cooling area & down aboveabove > GHG-induced warming aloft & inland> GHG-induced warming aloft & inland > Shallow warming over ocean from SST > Shallow warming over ocean from SST increasesincreases > NCEP-cooling over ocean & sea-breeze > NCEP-cooling over ocean & sea-breeze induced cooling over previously-warm coastal induced cooling over previously-warm coastal land-area (both to about 500-m) land-area (both to about 500-m) • z-line is eastern-edge of subsequent w-sectionz-line is eastern-edge of subsequent w-section

PastPastNowNow

N - PN - PT(oC)

Stat. sig. for previous z-section at 33.83 Stat. sig. for previous z-section at 33.83 N N

for temp-changes of for temp-changes of Domain-2Domain-2

• SST warming, cooling over ocean aloft, & coastal cooling: all significant at > 99%SST warming, cooling over ocean aloft, & coastal cooling: all significant at > 99%

• transition zone is less significanttransition zone is less significant

• Note: topography not shownNote: topography not shown

z-section w (cm/s) at 14 LT• Top L: Run-1 (Now): Subsidence over ocean & up-motion max over-peaks• Top R: Run-2 (Past): Patten similar to Run-1, but up-motion was stronger • Bottom R: Run-1 minus Run-2 (N-P) > Subsidence decreases (less negative, yellow) over ocean, as thermal-L expansion weakens Pacific-H > The area of decreased up-motion (less positive, blue) is due to increased marine-air stability and is bisected by a narrow area of increased (yellow) up-motion, as topo-graphic-induced up-motion overcomes stability effect

PastPastNowNow

N-PN-P

Urban areas:Urban areas: • UHI-peaks at 16 LT (1.0 UHI-peaks at 16 LT (1.0 ooC) C) • SB-retardation peaks (1.5 SB-retardation peaks (1.5 m/s) at 16 LT (Run-1 vector m/s) at 16 LT (Run-1 vector onshore & difference-vector onshore & difference-vector offshore) due to urban zoffshore) due to urban z0--decelerationdecelerationRural:Rural: • small inland-directed small inland-directed warm-air advection (0.2 warm-air advection (0.2 ooC) C) • insignificant Mt-top & insignificant Mt-top & over-ocean cooling over-ocean cooling (secondary-circulation (secondary-circulation effect?)effect?)• Costal park-insert shows Costal park-insert shows SB induced-cooling w/o the SB induced-cooling w/o the retardation-effect retardation-effect

2002 JJA 12, 14 & 16 LT Run 1 (Urban) minus Run 3 (no-Urban): Temp & U (1 barb = 0.5 m/s) differ-ences (U minus no U)

URBANIZATION RESULT (one slide):URBANIZATION RESULT (one slide):

12 LT12 LT

14 LT14 LT

16 LT16 LT

T (oC)

SummarySummaryThe effects of The effects of urbanization & GHG- warmingurbanization & GHG- warming on summer sea breezes in on summer sea breezes in

the SoCAB were studied by the SoCAB were studied by

> RAMS meso-met modeled PBL winds & temps> RAMS meso-met modeled PBL winds & temps

> comparison of RAMS temps with observed near-sfc values> comparison of RAMS temps with observed near-sfc values

• Increased GHGs (Run-1 vs. Run-2) resulted inIncreased GHGs (Run-1 vs. Run-2) resulted in

> increased sea-breezes over the ocean & coastal plain, and thus> increased sea-breezes over the ocean & coastal plain, and thus

> sea-breeze induced coastal-cooling over the coastal plain (whose > sea-breeze induced coastal-cooling over the coastal plain (whose aerial extent & magnitude aerial extent & magnitude matchedmatched the observations) the observations)

• Urbanization produced andUrbanization produced and

> UHI and a > UHI and a

> reduced sea-breeze penetration (due to the large urban-z> reduced sea-breeze penetration (due to the large urban-z00))

• Implications from coastal-coolingImplications from coastal-cooling

> Lower energy-use for cooling> Lower energy-use for cooling

> Lower heat-stress levels> Lower heat-stress levels

> Lower peak O> Lower peak O33 concentrations concentrations

> Benefits for peak-temperature sensitive agriculture > Benefits for peak-temperature sensitive agriculture

Other places where Other places where costal-cooling might occurcostal-cooling might occur

From IPCCFrom IPCC

Future Future workwork

> > Scientific questionsScientific questions• What are future changes in coastal cooling?What are future changes in coastal cooling?• When and how coastal cooling stop, if ever?When and how coastal cooling stop, if ever?• Is there an index that can predict coastal cooling in other Is there an index that can predict coastal cooling in other

areas?areas?

> Extend observational data analysis to> Extend observational data analysis to• Other months Other months • Extreme valuesExtreme values

> Additional RAMS modeling of> Additional RAMS modeling of• Future GHG vs. LULC impactsFuture GHG vs. LULC impacts• SFBA and other areas SFBA and other areas

> Impact-analyses of> Impact-analyses of • Energy use Energy use • Air quality Air quality • Heat stressHeat stress

• Lebassi, B. H, J. E. González, D. Fabris, E. Maurer, C. Milesi, and Lebassi, B. H, J. E. González, D. Fabris, E. Maurer, C. Milesi, and R. Bornstein, 2010: R. Bornstein, 2010: RAMS modeled differences between 1970 RAMS modeled differences between 1970 and 2005 summer daytime temperatures and winds in coastal and 2005 summer daytime temperatures and winds in coastal Southern Cali-forniaSouthern Cali-fornia. J. Climate (in preparation).. J. Climate (in preparation).

• Lebassi, B. H, J. E. González, D. Fabris, E. Maurer, N. L. Miller, C. Lebassi, B. H, J. E. González, D. Fabris, E. Maurer, N. L. Miller, C. Milesi, P. Switzer, and R. Bornstein, 2009: Observed 1970-2005 Milesi, P. Switzer, and R. Bornstein, 2009: Observed 1970-2005 cooling of summer daytime temperatures in coastal California, cooling of summer daytime temperatures in coastal California, J. Climate, J. Climate, 2222, 3558-3573, doi:10.1175/2008JCLI2111.1., 3558-3573, doi:10.1175/2008JCLI2111.1.

• Lebassi, B., J. JE. Gonzalez, R. Bornstein, and, D. Fabris, 2009: Lebassi, B., J. JE. Gonzalez, R. Bornstein, and, D. Fabris, 2009:

Regional impacts in the coastal California environment from a Regional impacts in the coastal California environment from a changing climate. J. Solar Energy and Engineering (to appear changing climate. J. Solar Energy and Engineering (to appear in August).in August).

• Lebassi B., D. Fabris, J. E. Gonzalez, S. Zarantonello, S. Lebassi B., D. Fabris, J. E. Gonzalez, S. Zarantonello, S. Chiappari, N. L. Miller, and R. Bornstein, 2005: Urban heat Chiappari, N. L. Miller, and R. Bornstein, 2005: Urban heat islands in California’s Central Valley, islands in California’s Central Valley, BAMSBAMS, 1542-1543. , 1542-1543.

JOURNAL PUBLICATIONSJOURNAL PUBLICATIONS

Presentation and extended abstract publicationsPresentation and extended abstract publications• RAMS modeled differences between 1970 and 2005 summer day time temperatures and winds in coastal California, B. RAMS modeled differences between 1970 and 2005 summer day time temperatures and winds in coastal California, B.

Lebassi, and JE. Gonzalez, and R. Bornstein, presented at the 34th Climate Diagnostics and Prediction Workshop, Lebassi, and JE. Gonzalez, and R. Bornstein, presented at the 34th Climate Diagnostics and Prediction Workshop, Monterey, CA, October 26-30, 2009.Monterey, CA, October 26-30, 2009.

• Modelling the Impacts of Urbanization vs. Green House Gas Warming in Southern California Coasts, B. Lebassi, and J. JE. Modelling the Impacts of Urbanization vs. Green House Gas Warming in Southern California Coasts, B. Lebassi, and J. JE. Gonzalez, and R. Bornstein, Second International Conference on Countermeasures to Urban Heat Islands, LBNL, Gonzalez, and R. Bornstein, Second International Conference on Countermeasures to Urban Heat Islands, LBNL, Berkeley, California, 21-23 September, 2009.Berkeley, California, 21-23 September, 2009.

• Regional energy-use impacts in the coastal California environment from a changing climate, B. Lebassi, J. Gonzalez, R. Regional energy-use impacts in the coastal California environment from a changing climate, B. Lebassi, J. Gonzalez, R. Bornstein, and R. Van Buskirk, The 7th International conf on Urban Climate, Yokohama, Japan. June 29- July 3, 2009.Bornstein, and R. Van Buskirk, The 7th International conf on Urban Climate, Yokohama, Japan. June 29- July 3, 2009.

• Modeling differences between 1970 and 2005 summer daytime temperatures in coastal California, B. Lebassi, J. Modeling differences between 1970 and 2005 summer daytime temperatures in coastal California, B. Lebassi, J. Gonzalez, and R. Bornstein, the 7th International conf on Urban Climate, Yokohama, Japan. June 29- July 3, 2009.Gonzalez, and R. Bornstein, the 7th International conf on Urban Climate, Yokohama, Japan. June 29- July 3, 2009.

• Regional Impacts on Energy Demands from a Changing Climate in the Coastal California Environment,Regional Impacts on Energy Demands from a Changing Climate in the Coastal California Environment, B. Lebassi, JE. B. Lebassi, JE. Gonzalez, D. Fabris, and R. Bornstein, Inaugural US-EU-China Thermophysics Conf. Renewable Energy, UECTC2009-342 Gonzalez, D. Fabris, and R. Bornstein, Inaugural US-EU-China Thermophysics Conf. Renewable Energy, UECTC2009-342 (Invited Paper). Beijing, China, 28-30 May, 2009.(Invited Paper). Beijing, China, 28-30 May, 2009.

• Cooling summer daytime temperatures in two urban coastal California air basins during 1948-2005: observations and Cooling summer daytime temperatures in two urban coastal California air basins during 1948-2005: observations and implications, R. Bornstein, B. Lebassi, E. Maurer, P. Switzer, and J. E. Gonzalez, presented 8th Conf. on Coastal implications, R. Bornstein, B. Lebassi, E. Maurer, P. Switzer, and J. E. Gonzalez, presented 8th Conf. on Coastal Atmospheric and Oceanic Prediction and Processes, 89th AMS Annual Meeting, Phoenix, AZ, 10-15 January 2009.Atmospheric and Oceanic Prediction and Processes, 89th AMS Annual Meeting, Phoenix, AZ, 10-15 January 2009.

• Regional Impacts on Energy Demands from a Changing Climate in Coastal California Environments, 2009: J.E. Gonzalez, Regional Impacts on Energy Demands from a Changing Climate in Coastal California Environments, 2009: J.E. Gonzalez, B. Lebassi, R. D. Bornstein, H. Taha, and R. D. Van Buskirk, presented at Eighth Conference on Coastal Atmospheric and B. Lebassi, R. D. Bornstein, H. Taha, and R. D. Van Buskirk, presented at Eighth Conference on Coastal Atmospheric and Oceanic Prediction and Processes, 89th AMS Annual Meeting, Phoenix, AZ, 10-15 January 2009.Oceanic Prediction and Processes, 89th AMS Annual Meeting, Phoenix, AZ, 10-15 January 2009.

• Observed and simulated California climate trends due to concurrent long-term inland-warming and coastal-cooling, B. Observed and simulated California climate trends due to concurrent long-term inland-warming and coastal-cooling, B. Lebassi, and J. E. Gonzalez, R. Bornstein, and D. Fabris; presented at The 17th Joint Conference on Planned and Lebassi, and J. E. Gonzalez, R. Bornstein, and D. Fabris; presented at The 17th Joint Conference on Planned and Inadvertent Weather Modification/Weather Modification Association Annual Meeting, Westminster, CO, 20-25 April 2008.Inadvertent Weather Modification/Weather Modification Association Annual Meeting, Westminster, CO, 20-25 April 2008.

• RAMS simulations of a global-warming reverse-reaction: California coastal summer daytime cooling, B. Lebassi, Santa RAMS simulations of a global-warming reverse-reaction: California coastal summer daytime cooling, B. Lebassi, Santa Clara University, Santa Clara, CA; and J. E. Gonzalez, D. Fabris, E. Maurer, N. L. Miller, C. Milesi, and R. Bornstein; Clara University, Santa Clara, CA; and J. E. Gonzalez, D. Fabris, E. Maurer, N. L. Miller, C. Milesi, and R. Bornstein; present at 88th AMS conference, 20th Conf on Climate Variability and Change, New Orleans, LA, 20-24 January, 2008.present at 88th AMS conference, 20th Conf on Climate Variability and Change, New Orleans, LA, 20-24 January, 2008.

• Observations of a global-warming reverse-reaction: California coastal summer daytime cooling, R. Bornstein, B. Lebassi, Observations of a global-warming reverse-reaction: California coastal summer daytime cooling, R. Bornstein, B. Lebassi, J. E. Gonzalez, D. Fabris, E. Maurer, N. L. Miller, and C. Milesi; present 88th AMS Conf, 20th Conf on Climate Variability J. E. Gonzalez, D. Fabris, E. Maurer, N. L. Miller, and C. Milesi; present 88th AMS Conf, 20th Conf on Climate Variability and Change. New Orleans, 20-24 January, 2008.and Change. New Orleans, 20-24 January, 2008.

• Spatial and Temporal Changes in Climatological Degree-Days in California, B. Lebassi. E. Gonzalez, R. Bornstein, D. Spatial and Temporal Changes in Climatological Degree-Days in California, B. Lebassi. E. Gonzalez, R. Bornstein, D. Fabris, Energy Sustainability, Long Beach, CA, 10-13 January, 2007.Fabris, Energy Sustainability, Long Beach, CA, 10-13 January, 2007.

• Observed long-term California temperature-trends: coastal cooling and inland warming, 2007: B. Lebassi, J. E. Gonzles, Observed long-term California temperature-trends: coastal cooling and inland warming, 2007: B. Lebassi, J. E. Gonzles, D. Fabris, E. Maurer, R. Bornstein, and N. L. Miller; presented at 87th AMS annual Symposium, Connections Between D. Fabris, E. Maurer, R. Bornstein, and N. L. Miller; presented at 87th AMS annual Symposium, Connections Between Mesoscale Processes and Climate Variability, Santa Antonio, TX, 14-18 January, 2007.Mesoscale Processes and Climate Variability, Santa Antonio, TX, 14-18 January, 2007.

• Impacts of Land Use and Land Cover on Regional Summer Time Coastal Cooling and Inland Warming in Central Impacts of Land Use and Land Cover on Regional Summer Time Coastal Cooling and Inland Warming in Central California, 2007: Jorge E. González, B. Lebassi and R. Bornstein; presented at Seventh Conference on Coastal California, 2007: Jorge E. González, B. Lebassi and R. Bornstein; presented at Seventh Conference on Coastal Atmospheric and Oceanic Prediction and Processes, San Diego California, 10-13 September, 2007.Atmospheric and Oceanic Prediction and Processes, San Diego California, 10-13 September, 2007.

• Modeling urban heat islands in California central valley, B. Lebassi, J. E. González, D. Fabris, N. L. Miller, and C. Milesi; Modeling urban heat islands in California central valley, B. Lebassi, J. E. González, D. Fabris, N. L. Miller, and C. Milesi; presented at 86th AMS annual Symposium, Sixth Sym on the Urban Environment, Atlanta, GA. Jan 28- Feb 3, 2006.presented at 86th AMS annual Symposium, Sixth Sym on the Urban Environment, Atlanta, GA. Jan 28- Feb 3, 2006.

• Climatology temperature mapping for California urban heat island study site selection, Lebassi Bereket, D. Fabris, J. E. Climatology temperature mapping for California urban heat island study site selection, Lebassi Bereket, D. Fabris, J. E. Gonzalez, S. Zarantonello, S. Chiappari, N. L. Miller, and R. Bornstein. Presented at Atm Sci and Air Quality Conf., San Gonzalez, S. Zarantonello, S. Chiappari, N. L. Miller, and R. Bornstein. Presented at Atm Sci and Air Quality Conf., San Francisco, CA, 27-29 April, 2005.Francisco, CA, 27-29 April, 2005.

Thank You!Thank You!

Any Questions? Any Questions?