1. The Effect of SW Drought on Precipitation of Evapotranspired Origin 1.Hydrology and Water Resources 2.Atmospheric Sciences 3.School of Natural Resources 4.Universidad de Antioquia, Colombia Francina Dominguez 1,2 Juan Camilo Villegas 3,4 David D. Breshears 3

2. The goal is to understand how hydrologic variability in the Southwest affects the export of moisture Dynamic precipitation recycling model Effect of SW Drought on subsequent Precipitation Export of Moisture from the SW Region

3. “Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. (Pringle, 2001) The atmospheric paths of moisture that connect hydrologic units are poorly understood. What are the effects of changes in atmospheric hydrologic connectivity? atmospheric surface sub surface

4. Dynamic Precipitation Recycling Model Dynamic Recycling Model Dominguez, F. et al., 2006. J. Climate

5. The principle for all analytic recycling models is the conservation of atmospheric moisture In the past, recycling models have assumed that the change in moisture storage is negligible. New model relaxes this assumption Dynamic Recycling Model R =  (local recycling ratio)  w  (precipitable water)  E  (evapotranspiration)

6. In order to solve the equation we change the coordinate system to follow the motion of the air. To solve, change coordinate system. We basically follow the path of the air. The equation becomes a simple ODE. R =  (local recycling ratio)  w  (precipitable water)  E  (evapotranspiration) Dynamic Recycling Model

7. In addition to recycling ratios, we can calculate source-sink regions of atmospheric moisture. Dynamic Recycling Model

8. What is the spatial extent of precipitation originating as ET from the South Western US? Export of SW ET ? North American Regional Reanalysis (NARR) data. Warm season (Apr-Sep)

9. Jul 1-15 (1996-1999) Evapotranspiration from the South West affects precipitation across the United States. Precipitation originating as ET from SW region. Percent of total Precipitation (falling in each pixel) that originates as ET from SW region. Export of SW ET

10. Jul 16-31 (1996-1999) Evapotranspiration from the South West affects precipitation across the United States. Precipitation originating as ET from SW region. Percent of total Precipitation (falling in each pixel) that originates as ET from SW region. Export of SW ET

11. Aug 1-15 (1996-1999) At the peak of the Monsoon season, we see a peak in recycled precipitation. Precipitation originating as ET from SW region. Percent of total Precipitation (falling in each pixel) that originates as ET from SW region. Export of SW ET

12. Aug 16-31 (1996-1999) At the peak of the Monsoon season, we see a peak in recycled precipitation. Precipitation originating as ET from SW region. Percent of total Precipitation (falling in each pixel) that originates as ET from SW region. Export of SW ET

13. Sep 1-15 (1996-1999) Toward the end of the Monsoon, RP diminishes. Precipitation originating as ET from SW region. Percent of total Precipitation (falling in each pixel) that originates as ET from SW region. Export of SW ET

14. Sep 16-30 (1996-1999) Toward the end of the Monsoon, RP diminishes. Precipitation originating as ET from SW region. Percent of total Precipitation (falling in each pixel) that originates as ET from SW region. Export of SW ET

15. Effects of Southwest drought on subsequent precipitation of evapotranspired origin. Even though NARR doesn’t account for vegetation variability, ET varies as NDVI. Jul – Sep ET and PP NDVI for late May- June the region encompassing P. edulis (Breshears et al.,2005) NDVI

16. Precipitation originating as ET from 4-Corners Region varies in agreement with evapotranspiration. Drought and Recycling

17. The drought period presented a sharp decrease in precipitation originating as ET. Drought and Recycling Pre-Drought Severe Drought Drought Transition

18. This meant that the % of precipitation originating as SW-ET considerably diminished during the drought. Drought and Recycling Pre-Drought Severe Drought Drought Transition

19. Adjacent states receive approximately 10% of their Jul-Sep precipitation from the Southwest. Drought and Recycling This value dropped to around 6% during the drought

20. The Dynamic Recycling Model has enabled us to analyze the regions where ET from the Southwest contributes to precipitation. Including intraseasonal variability. Conclusions In conclusion… The recent SW drought had a significant impact on the precipitation originating as ET from the SW region.

21. Further Thoughts… NARR doesn’t include vegetation variability, hence doesn’t account for the regional-scale die-off. Could the vegetation die-off amplify the effect of the drought on remote precipitation?

22. Questions?