Impact of Deforestation on Precipitation

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Impact of Deforestation on Precipitation

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R. Avissar and D. R. Avissar and D. WerthWerthDuke UniversityDuke UniversityS.S. Baidya Baidya Roy Roy

Princeton UniversityPrinceton University C.P. Weaver C.P. Weaver

Rutgers UniversityRutgers University

Local, Regional and Global Effects of AmazonLocal, Regional and Global Effects of AmazonDeforestationDeforestation

OutlineOutline1. Regional impact of LU/LCC on convection:1. Regional impact of LU/LCC on convection: GCIP and LBA studies GCIP and LBA studies2.2. Teleconnections Teleconnections: A GCM analysis: A GCM analysis3. Conclusions and research direction3. Conclusions and research direction

Research funded byResearch funded byNOAA and NASANOAA and NASA

Does human modification of the landscape affect theDoes human modification of the landscape affect thecharacteristics of the atmosphere, the hydrologicalcharacteristics of the atmosphere, the hydrologicalcycle and water resources? If yes, where? What arecycle and water resources? If yes, where? What arethe spatial scales of forcing and the spatial scales ofthe spatial scales of forcing and the spatial scales ofresponse? To what extent? And when?response? To what extent? And when?

Scientific Questions Scientific Questions

Grid 1

Grid 2

Grid 3

Simulation CharacteristicsSimulation Characteristics 3 nested grids (2x2; 8x8; 32x323 nested grids (2x2; 8x8; 32x32km);km); 38 vertical levels up to 22 km 6 38 vertical levels up to 22 km 6a.m. - 6 p.m.;a.m. - 6 p.m.; 10 s time step in Grid 3; 10 s time step in Grid 3; NCEP reanalysis assimilated in NCEP reanalysis assimilated inGrid 1, including wind,Grid 1, including wind,geopotential height, potentialgeopotential height, potentialtemperature, and relativetemperature, and relativehumidity;humidity; Surface fluxes from Surface fluxes from ZhongZhong and andDoran derived from ARM/CARTDoran derived from ARM/CARTobservations and RAMS surfaceobservations and RAMS surfacescheme in Grids 1 & 2, withscheme in Grids 1 & 2, withIGBP vegetation class;IGBP vegetation class; Subgrid Subgrid-scale turbulence of-scale turbulence ofMellorMellor & & YamadaYamada;; Radiation of Chen and Cotton. Radiation of Chen and Cotton.

Raingauge & WeatherSurveillance Doppler Radar(WSR-88D) Network ofArkansas-Red Basin RiverForecast Center (ABRFC)

http://www.abrfc.noaa.gov

Impact of surface heat flux heterogeneity

With observed fluxes With domain-averaged fluxes

Horizontal cross-section of w (m/s), 1300 m above ground surface

July 13, 1995July 13, 1995

July 21, 1995July 21, 1995

July 06, 1995July 06, 1995

July 10, 1995July 10, 1995

July 07, 1995July 07, 1995

July 12, 1995July 12, 1995

8

9

10

11

12

13 65 64 63 62 61 60

Simulation CharacteristicsSimulation Characteristics 3 nested grids (1x1; 4x4; 16x16 3 nested grids (1x1; 4x4; 16x16km grid-spacing);km grid-spacing); 38 vertical levels up to 24 km; 38 vertical levels up to 24 km; 7 a.m. - 7 p.m.; 7 a.m. - 7 p.m.; 5 s time step in Grid 3; 5 s time step in Grid 3; NCEP reanalysis assimilated in NCEP reanalysis assimilated inGrid 1, including wind,Grid 1, including wind,geopotentialgeopotential height, potential height, potentialtemperature, and relative humidity;temperature, and relative humidity; Surface fluxes from RBLE3 Surface fluxes from RBLE3observations and RAMS soil-observations and RAMS soil-vegetation model in Grid 1, withvegetation model in Grid 1, withIGBP vegetation class;IGBP vegetation class; Subgrid Subgrid-scale turbulence of-scale turbulence ofMellorMellor & & YamadaYamada;; Radiation of Chen and Cotton. Radiation of Chen and Cotton.

ww (m/s) at 3 p.m., 500 m (m/s) at 3 p.m., 500 m Clouds at 3 p.m. (from GOES)Clouds at 3 p.m. (from GOES)

Impact of surface heat flux heterogeneity

TeleconnectionTeleconnection Experiment Experiment

Use of the GISS Model II GCM toUse of the GISS Model II GCM tostudy regional and global effectsstudy regional and global effectsof the Amazon deforestation;of the Amazon deforestation;

““ControlControl”” has mix of forests and has mix of forests andgrassland (current vegetation);grassland (current vegetation);

““DeforestationDeforestation”” assumes that the assumes that theAmazon Amazon rainforestrainforest is converted is convertedinto a mix of shrub andinto a mix of shrub andgrassland;grassland;

Six 12-year realizations for eachSix 12-year realizations for eachcase.case.

4x5 degree resolution;4x5 degree resolution; Heat and humidity Heat and humidity advectedadvected

with quadratic upstreamwith quadratic upstreamscheme;scheme;

Momentum Momentum advected advected withwith2nd order scheme;2nd order scheme;

Second order closure PBL;Second order closure PBL; 6 soil layers, hydrology;6 soil layers, hydrology; Climatological Climatological SSTs.SSTs.

WestWestPacificPacificIndianIndian

Ocean Ocean

CentralCentralAmericaAmerica

AmazonAmazon

NCANCA

SEASEA

GulfGulf

AustraliaAustralia

EuropeEurope

IndiaIndiaCentralCentralAfricaAfrica

SouthSouthAfricaAfrica

CentralCentralAsiaAsia

NorthNorthAsiaAsia

Amazon

012345678

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Gulf of Mexico

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7

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/day

Central America

2

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/day

Indian Ocean

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/day

West Pacific

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/day

DakotasDakotas

MidwestMidwestTriangleTriangle

NORTH CENTRALNORTH CENTRAL

Dakotas

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/day

Total Precipitation Difference(Threshold Value is 0.125 mm/day)

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J F M A M J J A S O N D

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Deforest-Control (True Ensemble) Mean of False Ensembles

““TrueTrue”” ensemble ensemble

““FalseFalse”” ensembles ensembles

−

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DDDDDD

CCCCCC

−−

−−

−−

−−

−−

−−

−−

−−

−−

−−

−−

−−

4364

6253

5121

5365

4243

3121

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3121

DDDDDDDDDDDDDDDDDDDDDDDDCCCCCCCCCCCCCCCCCCCCCCCC

Both in the Amazon and the Central US regions, the atmospheric boundaryBoth in the Amazon and the Central US regions, the atmospheric boundarylayer is significantly affected by land use / land cover change (LU/LCC);layer is significantly affected by land use / land cover change (LU/LCC); LU/LCC in the Amazon significantly affects the regional LU/LCC in the Amazon significantly affects the regional hydro hydro--climatologyclimatology of South America and other tropical regions, and to a lesser but of South America and other tropical regions, and to a lesser butstill significant degree, thestill significant degree, the hydroclimatology hydroclimatology of North America. of North America. ConvectiveConvectiveactivity is one of the key factors that trigger activity is one of the key factors that trigger teleconnections teleconnections between tropicalbetween tropicalregions and mid latitudes;regions and mid latitudes; Frequently, the landscape heterogeneity created by LU/LCC generates Frequently, the landscape heterogeneity created by LU/LCC generateshorizontal pressure gradients strong enough to generate and sustainhorizontal pressure gradients strong enough to generate and sustainorganizedorganized mesoscale circulations mesoscale circulations (synoptic flow determine the orientation of (synoptic flow determine the orientation ofthese these circulationscirculations);); These These circulationscirculations affect affect convectiveconvective activity, clouds and precipitation. activity, clouds and precipitation.These These circulations circulations are neither resolved by, nor are neither resolved by, nor parameterized parameterized in, in, GCMsGCMs..Clearly, this limits our capability to estimate the real magnitude ofClearly, this limits our capability to estimate the real magnitude ofteleconnections teleconnections between the Amazon and the rest of the world.between the Amazon and the rest of the world.

ConclusionsConclusions

Impact of Deforestation on Precipitation

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PublicationsPublications

Liu, Y. , C.P. Weaver, and R. Avissar, 1999. Towards the parameterizationLiu, Y. , C.P. Weaver, and R. Avissar, 1999. Towards the parameterizationof convection induced by landscape heterogeneity inof convection induced by landscape heterogeneity in GCMs GCMs. . J.J. Geophys Geophys.. Res Res..,,104104:19515-19533.:19515-19533.

Weaver, C.P. and R. Avissar, 2001. Atmospheric Disturbances Caused by Weaver, C.P. and R. Avissar, 2001. Atmospheric Disturbances Caused byHuman Modification of the Landscape. Human Modification of the Landscape. Bull.Bull. Amer Amer. Met.. Met. Soc Soc., ., 8282:269-281.:269-281.

BaidyaBaidya Roy, S. and R. Avissar. The impacts of land use / land cover change Roy, S. and R. Avissar. The impacts of land use / land cover changein the Amazon on its regionalin the Amazon on its regional hydroclimatology hydroclimatology. . J.J. Geophys Geophys.. Res Res. (LBA Special. (LBA SpecialIssue)Issue), accepted for publication., accepted for publication.

Weaver, C.P., S. Weaver, C.P., S. Baidya Baidya Roy, and R. Avissar. A sensitivity analysis of large- Roy, and R. Avissar. A sensitivity analysis of large-scale boundary-layer characteristics to initialization and forcing underscale boundary-layer characteristics to initialization and forcing underrealistic meteorological and surface conditions. realistic meteorological and surface conditions. J.J. Geophys Geophys.. Res Res. (LBA Special. (LBA SpecialIssue)Issue), in revision., in revision.

WerthWerth, D. and R. Avissar. Regional and global impacts of Amazon, D. and R. Avissar. Regional and global impacts of Amazondeforestation. deforestation. J.J. Geophys Geophys.. Res Res. (LBA Special Issue). (LBA Special Issue), accepted for publication., accepted for publication.

Werth Werth, D. and R. Avissar. Amazon evaporation, clouds, and radiation. , D. and R. Avissar. Amazon evaporation, clouds, and radiation. J.J.GeophysGeophys.. Res Res. (LBA Special Issue). (LBA Special Issue), in revision., in revision.

January Amazon

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August Central America

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1 2 3 4 5 6 7 8

year

mm

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February West Pacific

66.57

7.58

8.59

1 2 3 4 5 6 7 8

year

mm

/day

August Gulf of Mexico

2

3

4

5

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7

1 2 3 4 5 6 7 8

year

mm

/day

October Indian Ocean

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6

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7

1 2 3 4 5 6 7 8

year

mm

/day