11

CoolingCooling summer daytime temperatures summer daytime temperatures in two in two urbanurban coastal CA air basins coastal CA air basins

during 1948-2005: during 1948-2005: observations and observations and implicationsimplications

Prof. Robert BornsteinProf. Robert Bornstein

Dept. of Meteorology, SJSUDept. of Meteorology, SJSUpblmodel@hotmail.com

Bereket Lebassi, Jorge GonzalezBereket Lebassi, Jorge Gonzalez

Dept. of Mechanical Engineering, SCUDept. of Mechanical Engineering, SCU

Presented atPresented atAMS Annual Meeting, Phoenix, AZAMS Annual Meeting, Phoenix, AZ

Jan 2009Jan 2009

22

ACKNOWLEDGMENTSACKNOWLEDGMENTS

FUNDING PROVIDED BY:FUNDING PROVIDED BY:

• SANTA CLARA UNIVERSITYSANTA CLARA UNIVERSITY

• NSFNSF

• USAIDUSAID

33

OVERVIEW• BACKGROUNDBACKGROUND• DATADATA• ANALYSESANALYSES• RESULTSRESULTS

– ALL OF CALIFORNIAALL OF CALIFORNIA– COASTAL VS. INLANDCOASTAL VS. INLAND– UHI IMPACTSUHI IMPACTS

• IMPLICATIONSIMPLICATIONS• FUTURE EFFORTSFUTURE EFFORTS

to appearto appear, J. of Climate as Lebassi et al. , J. of Climate as Lebassi et al. (2009)(2009)

44

““The” research-problemThe” research-problem

• What are the impacts of global climate change What are the impacts of global climate change on CAon CA– climate, e.g., seasonal and daily temperature trendsclimate, e.g., seasonal and daily temperature trends– weather, e.g., precipitation and water supplyweather, e.g., precipitation and water supply– air quality, e.g., ozone and PMair quality, e.g., ozone and PM– energy planning, e.g., for peak usageenergy planning, e.g., for peak usage– human health, e.g., human health, e.g., UHI and thermal stress levelsUHI and thermal stress levels– agriculture, e.g., winery operationsagriculture, e.g., winery operations

• (Not covered in this paper) How can meso-met (Not covered in this paper) How can meso-met modeling best be used tomodeling best be used to – reproduce past changes reproduce past changes – estimate future trends estimate future trends

55

Background Background (1 of 2)(1 of 2)

• Global scale observations Global scale observations generallygenerally show past show past asymmetric (more for Tasymmetric (more for Tminmin than for T than for Tmaxmax) warming ) warming accelerated since mid-1970s onaccelerated since mid-1970s on– global scale (1.0-2.5 deg resolution) global scale (1.0-2.5 deg resolution) (see graph)(see graph) – regional scales regional scales

• Global-model results Global-model results – match the observationsmatch the observations– predict accelerated further warming predict accelerated further warming

• CA downscaledCA downscaled global-model results global-model results (see 2(see 2ndnd graph)graph) – have been done (at have been done (at SCUSCU & elsewhere) onto 10 km grids & elsewhere) onto 10 km grids – show summer warming that show summer warming that decreases towards coast decreases towards coast

(but no cooling)(but no cooling)

66

Not much change from mid-40s to mid-70s, when valuesstarted to again rapidly rise

77

Statistically down-scaled (Prof. Maurer, Statistically down-scaled (Prof. Maurer, SCUSCU) 1950-2000 ) 1950-2000 Summer (JJA)Summer (JJA) IPCC temp-changes ( IPCC temp-changes (00C) show warming C) show warming rates that decrease towards coast; rates that decrease towards coast; red dotsred dots are COOP are COOP

sites used in present study & sites used in present study & boxesboxes are study sub-areas are study sub-areas

88

Background (2 of 2): Previous CA studies Background (2 of 2): Previous CA studies (next 2 slides)(next 2 slides) have explained their have explained their

climate-change obs in terms of increased climate-change obs in terms of increased GHGs & increased:GHGs & increased:

• Coastal upwelling:Coastal upwelling: Bakum (1990)Bakum (1990)

• SSTs & urbanization:SSTs & urbanization: Goodridge (1991) Goodridge (1991)

• Cloud cover:Cloud cover: Nemani et al. (2001)Nemani et al. (2001)

• UHIs: UHIs: Duffy et al. (2006)Duffy et al. (2006)

• IrrigationIrrigation – Christy et al. (2006)Christy et al. (2006)– Bonfils and Lobell (2007)Bonfils and Lobell (2007)– Lobell and Bonfils (2008)Lobell and Bonfils (2008)

99

Publication Parameter Studied Finding

Goodridge (1991)

80 years of annual-average daily Tave

at 112 site

Warming in both coastal (attributed to warming SSTs) & inland urban (attributed to UHI effects) areas; cooling in inland rural areas was unexplained

Nemani et al. (2001)

Sites in Napa & Son-oma Valleys during 1951-97 for Tmin & Tmax

Tmin increased & Tmax slightly

decreased, both attributed to measured increased cloud cover. Increased annual coastal TD

related to increased SSTs

Duffy et al. (2006)

Interpolated (to grid) monthly-average Tave from 1950-99

Warming in all seasons, attributed to increased UHIs or GHGs

Christy et al. (2006)

18 Central Valley sites from 1910-2003 for Tave Tmax,

& Tmin

Increased Tave & Tmin in all seasons,

greater in summer & fall. Summer cooling Tmax & warming

TD values attributed to increased

summer irrigation

1010

Bonfils & Duffy (2007)

Christy et al. (2006) Tmin

Warming Tmin not due to irri-gation,

which could only overcome GHG-warming for Tmax

Bonfils & Lobell (2007) and Lobell & Bonfils (2008)

Gridded Tmax &

Tmin

Expanded irrigation cooled sum-mer Tmax, while producing negli-

gible effects on Tmin

LaDochy et al. (2007)

331 sites during 1950-2000 for Tave, Tmin, & Tmax

Annual Tave warming at most sites.

Almost all increases due to changes in Tmin (max in summer), as Tmax

showed no change or cooling. Max Tave warming in southern CA, but

NE Interior Basin showed cooling

Abatzoglou et al. (2008)

Coastal sites during 1970-2000 for Tmax

Significant coastal cooling in late summer & early fall

1111

Current HypothesisCurrent Hypothesis

INCREASEDINCREASED GHG-INDUCED GHG-INDUCED INLAND TEMPSINLAND TEMPSINCREASED (COAST TO INCREASED (COAST TO INLAND) PRESSURE & TEMP INLAND) PRESSURE & TEMP GRADIENTSGRADIENTS INCREASED INCREASED SEA BREEZESEA BREEZE FREQ, INTENSITY, FREQ, INTENSITY, PENETRATION, &/OR PENETRATION, &/OR DURATION DURATION COASTAL AREAS SHOULD COASTAL AREAS SHOULD SHOW SHOW COOLING SUMMER COOLING SUMMER DAYTIME MAX TEMPSDAYTIME MAX TEMPS (i.e., A (i.e., A REVERSE REACTION)REVERSE REACTION)

NOTE:NOTE: NOT A TOTALLY ORIGINAL NOT A TOTALLY ORIGINAL IDEA IDEA

1212

CURRENT DATACURRENT DATA

• NCDC DAILY MAX & MIN 2-METER NCDC DAILY MAX & MIN 2-METER TEMPSTEMPS – FROM ABOUT 300 CA NWS COOP SITES FROM ABOUT 300 CA NWS COOP SITES – FOR 1948-2005FOR 1948-2005– USED IN MANY OTHER CA CLIMATE-USED IN MANY OTHER CA CLIMATE-

CHANGE STUDIESCHANGE STUDIES

• ERA40 1.4 DEG T-85 REANALYSIS ERA40 1.4 DEG T-85 REANALYSIS SUMMER (JJA) 1000-LST SUMMER (JJA) 1000-LST – SEA-LEVEL PRESSURE TRENDS SEA-LEVEL PRESSURE TRENDS – FOR 1970-2005FOR 1970-2005

1313

DATA ANALYSESDATA ANALYSES

• Emphasis: Emphasis: on summer (JJA) data from 1970-on summer (JJA) data from 1970-20052005

• All-CA warming/cooling trendsAll-CA warming/cooling trends calculated calculated ((00C/decade) for:C/decade) for: T Tmaxmax, T, Tminmin, Tave, & daily temp range (DTR = TTmaxmax -T -Tminmin)

• Spatial-distributions of TSpatial-distributions of Tmax trends: trends: plotted for plotted for thethe– South Coast Air Basin (SoCAB)South Coast Air Basin (SoCAB)– SFBA (includes northern Central Valley) SFBA (includes northern Central Valley)

• Tests of statistical significanceTests of statistical significance

• Land-sea sea-level pressuresLand-sea sea-level pressures– Spatial-distributions of 1979-2005 trendsSpatial-distributions of 1979-2005 trends– Temporal-trends for sea-level pressure-gradient Temporal-trends for sea-level pressure-gradient

1414

Results 1:Results 1: SoCAB 1970-2005 summer (JJA) T SoCAB 1970-2005 summer (JJA) Tmax max warming/ warming/ cooling trends (cooling trends (00C/decade); C/decade); ?=more data needed

solid, crossed, & open circles show solid, crossed, & open circles show stat p-valuesstat p-values < 0.01, < 0.01, 0.05, & not significant, respectively0.05, & not significant, respectively

??

????

1515

Results 2:Results 2: SFBA & Central Valley 1970-2005 JJA SFBA & Central Valley 1970-2005 JJA T Tmaxmax warming/cooling trends ( warming/cooling trends (00C/decade), as in previous C/decade), as in previous

figurefigure

??

??

??

1616

GOES10 imageGOES10 image of summertime marine Stratus of summertime marine Stratus penetration into Central Valley: penetration into Central Valley: supportssupports our our

inland coastal cooling boundary (Leoncini, inland coastal cooling boundary (Leoncini, 2002)2002)

1717

• LOWER TRENDSLOWER TRENDS FROM 1950- 70 FROM 1950- 70 (EXCEPT FOR T(EXCEPT FOR TMAX)

• Curve b:Curve b: T TMIN HAD HAD FASTEST RISE FASTEST RISE (AS (AS EXPECTED)EXPECTED)

• Curve c:Curve c: T TMAX HAD SLOWEST RISE; IT IS A SMALL-∆ b/t BIG POS VALUE & BIG NEG-VALUE (IN LAST 2 GRAPHS)

• CURVE a:CURVE a: TAVE THUS THUS ROSE AT MID RATE ROSE AT MID RATE

• Curve d:Curve d: DTR DTR ((diurnal temp diurnal temp rangerange) THUS ) THUS

DECREASED DECREASED (AS (AS TTMAX FALLS & FALLS & TTMIN RISES)RISES)

Results 3: JJA Temp trends; all CA-sitesAA

BB

CC

DD

1818

Significance of these Significance of these all-CA all-CA TrendsTrends• HIGHER TRENDS FROM 1970-2005 HIGHER TRENDS FROM 1970-2005

FOCUS NEEDED ON THIS PERIOD• TTMIN HAS FASTER RISE HAS FASTER RISE

ASSYMETRIC WARMING IN LITERATUREASSYMETRIC WARMING IN LITERATURE• BUTBUT T TMAX

– HAS SLOWER RISE– IT IS A SMALL DIFFERENCE B/T BIG POS-VALUE &

BIG NEG-VALUE (AS SEEN IN ABOVE SPATIAL PLOTS)

• TAVE & DTR DTR ARE ALSO THUS ARE ALSO THUS “CONTAMINATED” “CONTAMINATED” • NEXT 2 SLIDESNEXT 2 SLIDES THUS SHOWS THUS SHOWS SEPARATE SEPARATE

TRENDSTRENDS FOR CALIFORNIA FOR CALIFORNIA – COASTAL AREAS COASTAL AREAS – INLAND AREASINLAND AREAS

1919

Result 4: JJA TResult 4: JJA Tave, T, Tmin, T, Tmax, & DTR TRENDS FOR, & DTR TRENDS FOR

INLAND-WARMING INLAND-WARMING SITES OF SoCAB & SFBASITES OF SoCAB & SFBA

Curve b:Curve b: T TMIN IN-

CREASED (EXPECT- (EXPECT-ED)ED)

Curve c:Curve c: T TMAX FASTER RISE (UNEXPECTED), (UNEXPECTED), COULD BE DUE TO COULD BE DUE TO INCREASED INCREASED >UHIs>UHIsDOWN-SLOPE FLOWDOWN-SLOPE FLOW

CURVE a:CURVE a: TAVE THUS THUS

ROSE AT MID RATEROSE AT MID RATE

Curve d:Curve d: DTR THUS DTR THUS INCREASED, INCREASED, AS TAS TMAX ROSE FASTER THAN FASTER THAN TTMIN ROSE ROSE

bb

cc

aa

dd

2020

Result 5: JJA TResult 5: JJA Tave, T, Tmin, T, Tmax, & DTR TRENDS FOR , & DTR TRENDS FOR

COASTAL-COOLINGCOASTAL-COOLING SITES OF SoCAB & SFBA SITES OF SoCAB & SFBA

Curve b:Curve b: T TMIN ROSE ROSE

(EXPECTED)(EXPECTED)

Curve c:Curve c: T TMAX COOLING

(UNEXPECTED (UNEXPECTED MAJOR MAJOR RESULTRESULT OF STUDY) OF STUDY)

CURVE a:CURVE a: TAVE THUS SHOWED ALMOST NO CHANGE AS FOUND IN LITAS RISING TAS RISING Tmin & FALLING & FALLING

TTmax ALMOST CANCELLED OUT

Curve d:Curve d: DTR THUS DE- DTR THUS DE-CREASED, AS CREASED, AS TTMIN ROSE & TTMAX FELL FELL

aa

bb

cc

dd

2121

Trend in 1979-2002 ERA40 reanalysis of Trend in 1979-2002 ERA40 reanalysis of 1800 UTC (1000 LT) JJA 1800 UTC (1000 LT) JJA sea-level p-changessea-level p-changes

(hPa/decade)(hPa/decade)• dotsdots =1.4-deg =1.4-deg gridsgrids

• end-ptsend-pts of of solid lines = pts solid lines = pts for for p-grad p-grad trend trend calcu-lation calcu-lation (next slide)(next slide)

• H & L:H & L: both both strengthened & strengthened & moved to NW moved to NW (can’t see here)(can’t see here)

2222

Result 6:Result 6: Trends in sea minus land JJA 1800 Trends in sea minus land JJA 1800 UTC UTC

sea-level sea-level p- gradientp- gradient (hPa/100-km/decade) (hPa/100-km/decade)

from values at ends of lines in from values at ends of lines in previous Fig.previous Fig.

These stronger These stronger HPGFsHPGFs stronger stronger sea breezessea breezes coastal coastal coolingcooling

2323

IPCC 2001 does show cooling over Central California!!

2424

Significance of above Significance of above Coastal-Coastal-Cooling Cooling and Inland-Warming and Inland-Warming

trendstrends• CA ASSYMETRIC WARMINGCA ASSYMETRIC WARMING IN LITERATURE IN LITERATURE

IS HEREIN SHOWN TO BE DUE TO IS HEREIN SHOWN TO BE DUE TO – COOLING TTMAX IN COASTAL AREAS & – CONCURRENTCONCURRENT WARMING TTMAX IN INLAND AREAS

• PREVIOUS CA STUDIESPREVIOUS CA STUDIES – DID NOT LOOK SPECIFICALLY AT DID NOT LOOK SPECIFICALLY AT SUMMER SUMMER

DAYTIME COASTAL VS. INLAND VALUESDAYTIME COASTAL VS. INLAND VALUES HAVE HAVE – THEY THUS REPORTED THEY THUS REPORTED CONTAMINATEDCONTAMINATED T TMAX, ,

TTAVE, & DTR VALUES, & DTR VALUES– THEY, HOWEVER, ARE THEY, HOWEVER, ARE NOT INCONSISTENTNOT INCONSISTENT

WITH CURRENT RESULTS, THEY ARE JUST NOT WITH CURRENT RESULTS, THEY ARE JUST NOT AS AS DETAILEDDETAILED IN THEIR ANALYSES & RESULTS IN THEIR ANALYSES & RESULTS

2525

Result 7. JJA 1970-2005 2 m TResult 7. JJA 1970-2005 2 m Tmax max trends for 4 pairs of trends for 4 pairs of sites:sites:

urban (red, solid) urban (red, solid) && rural (blue, dashed) rural (blue, dashed)

Notes:Notes:1.1. All sites are near All sites are near

cooling-warming cooling-warming borderborder

1.1. UHI-TRENDUHI-TREND (K/decade)(K/decade)= = absolute sumabsolute sum b/t b/t warming-urban & warming-urban & cooling-rural cooling-rural trends trends

a. a. SFBASFBA sites sites > Stockton > Stockton (0.38 + 0.17 = (0.38 + 0.17 = 0.55)0.55)> Sac. (0.49)> Sac. (0.49)

b. b. SoCABSoCAB sites sites > Pasadena (0.26)> Pasadena (0.26) > S. Ana (0.12)> S. Ana (0.12)

uu

rr

2626

Notes on JJA daytime Notes on JJA daytime UHI-trendUHI-trend resultsresults

• Faster growingFaster growing cities (area & population) cities (area & population) had faster growing UHIs had faster growing UHIs (not shown)(not shown)

• As As no coastal sitesno coastal sites showed warming T showed warming Tmax

values, calculations could only be done atvalues, calculations could only be done at– these four pairs these four pairs – Located at the inland boundary of the warming Located at the inland boundary of the warming

and cooling areasand cooling areas

• Coastal sitesCoastal sites would have would have cooled even morecooled even more without their (assumed) growing UHIswithout their (assumed) growing UHIs

2727

SUMMARY OF CURRENT CA OBSSUMMARY OF CURRENT CA OBS • SUMMER TSUMMER Tminmin IN CALIF HAVE BEEN IN CALIF HAVE BEEN

WARMING FASTER THAN WARMING FASTER THAN TTmaxmax

• SUMMER DAYTIME TSUMMER DAYTIME Tmaxmax HAVE BEEN HAVE BEEN COOLING, COOLING, IN LOW-ELEVATION IN LOW-ELEVATION COASTALCOASTAL AIR-BASINSAIR-BASINS

• THE FOLLOWING AREAS ARE THE FOLLOWING AREAS ARE COOLING IN COOLING IN CENTRAL CA:CENTRAL CA:– MARINE LOWLANDSMARINE LOWLANDS– MONTEREYMONTEREY– SANTA CLARA VALLEYSANTA CLARA VALLEY– LIVERMORE VALLEYLIVERMORE VALLEY– WESTERN HALF OF SACRAMENTO VALLEYWESTERN HALF OF SACRAMENTO VALLEY

2828

Current results are Current results are unique, unique, as this study is first to:as this study is first to:

• segment obs in segment obs in allall the following ways the following ways– summer-values onlysummer-values only– TTmax & T & Tmin, as well as T, as well as Tave

– coastal vs. inland sitescoastal vs. inland sites

• consider sea-breeze enhancement consider sea-breeze enhancement – as causal mechanism of climate changeas causal mechanism of climate change– instead of: instead of: GHGs, irrigation, SST, UHI, PDO, GHGs, irrigation, SST, UHI, PDO,

&/or aerosols &/or aerosols (next slide)(next slide)

• do do data analyses data analyses && urbanized meso- urbanized meso-met modeling met modeling (not shown)(not shown)

2929

Possible explanations of coastal cooling Possible explanations of coastal cooling in the literaturein the literature

• GHGGHG warming:warming: – triggers secondary “reverse reaction” local effectstriggers secondary “reverse reaction” local effects– e.g., increased sea breeze activity e.g., increased sea breeze activity (our contention)(our contention)

• UHI development:UHI development: warms (& not cools) warms (& not cools)

• SST changes:SST changes: – GHG warming off Calif.-coast is stronger than GHG warming off Calif.-coast is stronger than

increased upwelling, increased upwelling, as as – SSTs are increasing SSTs are increasing (not shown)(not shown)

• PDO:PDO: uncorrelated to T uncorrelated to Tmax max (not shown)(not shown)

• Increased rural-irrigation:Increased rural-irrigation: – cools Tcools Tmaxmax

– important in Central Valleyimportant in Central Valley

3030

BENEFICIAL IMPLICATIONS OF BENEFICIAL IMPLICATIONS OF COASTAL COOLINGCOASTAL COOLING

• NAPA WINE AREAS NAPA WINE AREAS – MAY NOT GO EXTINCTMAY NOT GO EXTINCT – REALLY GOOD NEWS!REALLY GOOD NEWS! (next map)(next map)

• ENERGYENERGY FOR COOLINGFOR COOLING – MAY NOT INCREASE AS RAPIDLY AS POPULATION MAY NOT INCREASE AS RAPIDLY AS POPULATION – PAPER J21.4PAPER J21.4, THIS SESSION BY GONZALEZZ ET , THIS SESSION BY GONZALEZZ ET

AL.AL.

• LOWER HUMAN HEAT-STRESS RATESLOWER HUMAN HEAT-STRESS RATES• OO33 CONCENTRATIONS CONCENTRATIONS MIGHT CONTINUE TO MIGHT CONTINUE TO

DECREASE, AS LOWER TDECREASE, AS LOWER Tmaxmax REDUCES REDUCES– ANTHROPOGENIC EMISSIONSANTHROPOGENIC EMISSIONS– BIOGENIC EMISSIONSBIOGENIC EMISSIONS– PHOTOLYSIS RATESPHOTOLYSIS RATES

3131

NAPA WINE AREAS MAY NAPA WINE AREAS MAY NOT GO EXTINCTNOT GO EXTINCT DUE TO DUE TO ALLEGED RISING TALLEGED RISING TMAX VALUES, AS PREDICTED IN VALUES, AS PREDICTED IN NAS NAS

STUDYSTUDY

3232

GOOD IMPLICATIONS FOR OGOOD IMPLICATIONS FOR O3 • PAST & PROJECTED SFBA & SoCAB OPAST & PROJECTED SFBA & SoCAB O33

DECREASES MAYDECREASES MAY – IN-PART BE DUE TO DAYTIME TIN-PART BE DUE TO DAYTIME Tmaxmax COOLING-COOLING-

TRENDS and TRENDS and – NOT ONLY TONOT ONLY TO REDUCED ANTHROPOGENICREDUCED ANTHROPOGENIC

EMISSIONSEMISSIONS

• RECENT CARB AQMSsRECENT CARB AQMSs – HAVE NOT REPRODUCED FULL RATE OFHAVE NOT REPRODUCED FULL RATE OF

OBSERVED OOBSERVED O3-DECREASE-DECREASE– MAYBE (IN PART) DUE TO THIS UNMODELEDMAYBE (IN PART) DUE TO THIS UNMODELED

COOLING TRENDCOOLING TREND

3333

Future Coastal-Cooling EffortsFuture Coastal-Cooling Efforts (PART 1 (PART 1 OF 2)OF 2)

• EXPAND EXPAND (TO ALL OF CA & beyond)(TO ALL OF CA & beyond)– ANALYSIS OFANALYSIS OF OBS (IN-SITU & OBS (IN-SITU & GISGIS) ) – URBANIZEDURBANIZED MESO-MET (MM5, RAMS, WRF) MESO-MET (MM5, RAMS, WRF)

MODELING MODELING

• SEPARATE INFLUENCES SEPARATE INFLUENCES OF CHANGING OF CHANGING (via uRAMS modeling in SCU PhD of B. (via uRAMS modeling in SCU PhD of B. Lebassi):Lebassi):– LAND-USE PATTERNS LAND-USE PATTERNS

•AGRICULTURAL IRRIGATIONAGRICULTURAL IRRIGATION

•URBANIZATIONURBANIZATION

– SEA BREEZE:SEA BREEZE:INTENSITY, FREQ, DURATION, &/OR PENETRATION INTENSITY, FREQ, DURATION, &/OR PENETRATION

3434

POSSIBLE FUTURE EFFORTS POSSIBLE FUTURE EFFORTS (PART 2 OF 2)(PART 2 OF 2)

• DETERMINE POSSIBLE DETERMINE POSSIBLE “SATURATION”“SATURATION” OF SEA- OF SEA- BREEZE EFFECTS FROMBREEZE EFFECTS FROM– COLD-AIR TRANSPORTCOLD-AIR TRANSPORT– STRATUS-CLOUD EFFECTS ON LONG- & SHORT-WAVE STRATUS-CLOUD EFFECTS ON LONG- & SHORT-WAVE

RADIATIONRADIATION• DETERMINE CUMULATIVE FREQ DISTRIBUTIONSDETERMINE CUMULATIVE FREQ DISTRIBUTIONS

OF TOF TMAX VALUES, AS VALUES, AS– EVEN IF EVEN IF AVERAGEAVERAGE T TMAX DECREASES, DECREASES,– EXTREMEEXTREME VALUES T VALUES TMAX MAY STILL INCREASE (IN MAY STILL INCREASE (IN

INTENSITY &/OR FREQUENCY)INTENSITY &/OR FREQUENCY) • DETERMINE CHANGES IN LARGE-SCALE ATM DETERMINE CHANGES IN LARGE-SCALE ATM

FLOWS:FLOWS:– HOW DO GLOBAL CLIMATE-CHANGE EFFECT POSITION HOW DO GLOBAL CLIMATE-CHANGE EFFECT POSITION

& STRENGTH OF: & STRENGTH OF: PACIFIC HIGH & THERMAL LOW?PACIFIC HIGH & THERMAL LOW? – THESE TYPES OF CLIMATE-CHANGES ARE THE THESE TYPES OF CLIMATE-CHANGES ARE THE

ULTIMATE CAUSESULTIMATE CAUSES OF LOCAL TEMP & PRECIP OF LOCAL TEMP & PRECIP CHANGESCHANGES

3535

CoolingCooling summer daytime temperatures summer daytime temperatures in two in two urbanurban coastal CA air basins coastal CA air basins

during 1948-2005: observations and during 1948-2005: observations and implications implications

Prof. Robert BornsteinProf. Robert Bornstein

Dept. of Meteorology, SJSUDept. of Meteorology, SJSUpblmodel@hotmail.com

Bereket Lebassi, Jorge GonzalezBereket Lebassi, Jorge Gonzalez

Dept. of Mechanical Engineering, SCUDept. of Mechanical Engineering, SCU

QUESTIONS?QUESTIONS?