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Moisture transport from the tropical Atlantic

Integrated observed and modeled atmospheric water budget in the Amazon Basin: How much more can we ask from it? Jose A. Marengo, Carlos Nobre, Helio Camargo, Luiz Candido, Christopher Castro CPTEC/INPE Sao Paulo, Brazil. Moisture transport from the tropical Atlantic. Evapotranspiration.

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Moisture transport from the tropical Atlantic

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  1. Integrated observed and modeled atmospheric water budget in the Amazon Basin: How much more can we ask from it? Jose A. Marengo, Carlos Nobre, Helio Camargo, Luiz Candido, Christopher Castro CPTEC/INPE Sao Paulo, Brazil

  2. Moisture transport from the tropical Atlantic Evapotranspiration Runoff to Atlantic Ocean Rainfall Water balance in the Amazon Basin (perfect!)

  3. Water-Balance Approach (1) • Terrestrial water balance: • Atmospheric water balance: measured streamflow (Rs+Rg) • Combined water balance:

  4. Water-Balance Approach (2) • Assumptions: • The contributions of the liquid and solid phases of atmospheric water are negligible • The measured streamflow includes both the contributions of surface and groundwater runoff • Limitations: • Atmospheric water balance estimations are accurate only for domains > 105-106 km2 (Rasmusson 1968, Yeh et al. 1998

  5. Water-Balance Approach (3) • Changes in terrestrial water storage (dS/dt) in a given river basin can be estimated as the sum of three terms: : Convergence of the vertically integrated water vapour flux Reanalysis Data (NCEP) : Change in column storage of water vapour E : Evaporation (Latent Heat flux) P, R : Measured rainfall and streamflow Observations

  6. A DJF-CMAP B DJF-CRU C DJF-NCEP Precipitation (mm/day) D MAM-CMAP E MAM-CRU FR MAM-NCEP

  7. A SON B NDJ C MAM E JJA Evaporation (mm/day)

  8. A SON B DJF C MAM E JJA Moisture convergence (mm/day)

  9. Northeast Trades hPa 200 ET Moisture flux from Amazonia 300 400 Energy balance 500 600 LLJ Amazonia 700 LLJ Ta 800 Td N wind Altiplano 900 1000 MCS La Plata Basin The Low Level Jet east of the Andes (LLJ) Transports moisture from Amazonia to the Parana La Plata Basin (Marengo et al. 2004)

  10. Water budget 1970-99 the entire Amazon basin (using various rainfall data sets)

  11. Climatological water budget 1970-99

  12. Higher predictability Low Predictability Medium Predictability Seasonal climate predictability in South America LBA Medium predictability MONSOON PLATIN Medium predictability

  13. Water balance (mm/day) in the Amazon River Basin CPTEC COLA AGCM NCEP Rean+Obsv

  14. Energy balance (W/m2) in the Amazon River Basin CPTEC-COLA AGCM NCEP Rean+OBSV

  15. Precipitation Runoff CPTEC NCEP

  16. Evaporation (Latent heat) Sensible Heat

  17. Observed vs modelled precipitation NCEP-CPTEC NCEP-CRU

  18. Major differences in the behavior of the water balance between the northern and southern parts of the basin (seasonal to interannual variability) In present climates the entire basin behaves as a sink of moisture, while apparently northern Amazonia can act as a net source for moisture under extreme dry conditions (e.g. the strong 1983 El Niño event)In the future it will become source of moisture (HadCM3) Uncertainties in P in Amazonia, especially in the southern section can reach up to +1.0 mm/day. Some differences among rainfall data sets can reach up to 30% in rainfall and 15% in runoff. Estimates show a basin-wide imbalance of 51%, exhibiting an interannual variability. The choice of rainfall data set also has an impact in the imbalance in the water budget. Thus, significant uncertainties exist in these results and they are sensitive to the data used, in particular the atmospheric can hydrological data. CPTC AGCM underestimates P, R, E, overestimates H Conclusions- Imbalances in the water balance (1)

  19. The accuracy of the computed water balances depends critically on the domain size and on regional characteristics (climate, density of radiosonde data, topography?). The combined water-balance approach is a promising tool for estimating large-scale changes in terrestrial water storage Some limitations: Domain size needs to be at least > 2*105 km2 Additional validation data would be needed (E from Observations LBA Reference sites?) Aerological estimates of evaporation might be a useful proxy of reality and, when confronted with model evaporation, expose physical parametrization problems (we should take advantage of LBA reference site evaporation data). Nonetheless, the possible applications and uses are numerous given the dearth of observations of terrestrial water storage and its components Conclusions- Imbalances in the water balance (2)

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