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Multiscale Hydroclimatological Interactions: The Amazon Basin Case Study

Multiscale Hydroclimatological Interactions: The Amazon Basin Case Study Roni Avissar , Renato Ramos da Silva, David Werth , Natalia Hasler , Robert L. Walko , David Medvigy Research conducted at: Department of Civil and Environmental Engineering Duke University

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Multiscale Hydroclimatological Interactions: The Amazon Basin Case Study

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  1. MultiscaleHydroclimatological Interactions: The Amazon Basin Case Study RoniAvissar, Renato Ramos da Silva, David Werth, Natalia Hasler, Robert L. Walko, David Medvigy Research conducted at: Department of Civil and Environmental Engineering Duke University Amazon in Perspective: Integrated Science for a Sustainable Future November 2008 Manaus, Brazil

  2. Major Points… • Deforestation causes a regional shift of precipitation (regional teleconnections) in the Amazon basin, which seems to cause a disequilibrium between the eastern and western parts of the basin; • Deforestation of tropical regions affects the hydroclimatology of other regions (global teleconnections); • While modeling results indicate that the total amount of precipitation may not be affected by deforestation (neither at the regional nor at the global scale), the type of precipitation is changing from a so-called “green ocean” to convective precipitation; • In all of the above, eco-hydro-climatological feedbacks remain to be explored. Our models are getting considerably more complex (and hopefully better?!) and they can better resolve many more processes than in the past. Thus, they offer the opportunity to start exploring such feedbacks.

  3. RED: already deforested YELLOW and ORANGE: deforested by 2050 Soares Filho et al. 2004

  4. Simulations with RAMS mesoscale model 2) Wet seasons (Jan-Feb) were simulated for 1997 (very wet), 1998 (dry), and 1999-2000 (both “average”) 1) Horizontal resolution was 20 km Topography of the simulated domain Increasing precipitation Increasing precipitation • Four deforestation • scenarios were simulated 2030, BAU Control Higher elevation Lower elevation 2050, BAU Total (2100?)

  5. Impact of deforestation on regional precipitation Area a Area b (west) 1997 (wettest) Relative precipitation 1998 (driest) (southeast) 1999 (average) Relative deforestation Relative deforestation 2000 (average) (northeast) Area c Relative precipitation o Relative deforestation Ramos da Silva, Werth and Avissar, J. Climate, 21, 1153–1170, 2008.

  6. Impact on the basin as a whole Responses of GISS and RAMS, Amazon-wide precipitation Rondonia case study RAMS – 2 km Relative precipitation Relative precipitation RAMS – 20 km GCM Relative deforestation 4-yr mean RAMS: 20 km resolution GISS: 5 deg longitude by 4 deg latitude resolution.

  7. Five “multi-ensembles” of three GCMs (GISS, AM and CCM3), each used to produce six, 12-year realizations (with imposed monthly mean sea-surface temperatures): • Control – land-cover in early 70’s, before intensive deforestation started (Matthews, 1983); • Amazonian deforestation; • Central African deforestation; • South-Eastern Asian deforestation; • All three tropical regions deforested simultaneously (i.e., “total” deforestation). • Control case is compared to Cases (2) – (5). Each grid point is tested for monthly, ensemble mean, statistically significant difference in precipitation.

  8. Impact of Amazon deforestation on rainfall: GISS GCM ensemble Precipitation decreases PRECIPITATION [mm/day] Precipitation increases Colors: number of months with a significant deforestation effect Avissar and Werth, 2005

  9. Impact of Amazon deforestation on rainfall: GISS GCM ensemble Precipitation decreases PRECIPITATION [mm/day] Precipitation increases Colors: number of months with a significant deforestation effect Avissar and Werth, 2005

  10. The Ocean-Land-Atmosphere Model (OLAM): An expansion of RAMS into an Earth System Model Staggered C Grid; Shaved, Cartesian coordinates Icosahedron OLAM solves a finite-volume analog of the full compressible Navier-Stokes equations in conservation form, and exactly conserves mass and momentum. Unstructured Grid; No overlapping grid cell; No special nest communication; Each cell communicates directly with its neighbor independently of resolution

  11. Improving representation of topography improves OLAM’s precipitation estimates. Amazon Precipitation Amazon Precipitation 1997 1998 1999 2000 Medvigy, Walko, and Avissar, GRL, 2008

  12. Main Conclusions: • Deforestation causes regional teleconnections (Ramos da Silva, Werth and Avissar, 2008, J. Climate, 21, 1153-1170); • Deforestation of tropical regions causes global teleconnections (Avissar and Werth, 2005, J. Hydromet., 6, 134-145; Hasler, Werth and Avissar, 2008, J. Climate, in press); • The regional and global amount of precipitation may not be affected by deforestation but the type of precipitation is (work in progress); • In all of the above, eco-hydro-climatological feedbacks remain to be explored. This is possible with state-of-the-art Earth System Models, e.g., OLAM (Walko and Avissar, 2008a, Mon. Wea. Rev., 136, 4033-4044 and 2008b, Mon. Wea. Rev., 136, 4045-4062; Medvigy, Walko and Avissar, 2008, GRL, 35, L15817). • -- Further OLAM results: Thursday morning, 8:45am.

  13. Different models’ responses to tropical deforestation Precipitation increases Precipitation decreases GISS GM II GISS GM II GISS AM GISS AM CCSM CCSM

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