# Presentation: 894419

## Evaluating Key Uncertainties in IPCC Climate Change Projections of California snowpack: Topography, Snow Physics, and Aerosol Deposition

**Project Objectives:**
-  Examine the uncertainties in simulating the snowpack in the Sierra Nevada region that are associated with:
- Representation of the regional topography according to the horizontal resolution,
-  Representation of snow physics within the context of single vs. multi-layer framework.
- The alterations in snow albedo due to the deposition of aerosols, especially the anthropogenic black carbon (BC)

**Results:**
***The sensitivity of snowpack simulation due to model resolutions*****:**
***  ******Use of multi-layer snow model in simulating spring snowpack***
***The effects of snow albedo on the cold season Sierra Nevada snowpack***

**Evaluating Key Uncertainties in IPCC Climate Change Projections of California snowpack: Topography, Snow Physics, and Aerosol Deposition**

**Publications:**
- D. Waliser, J. Kim, K. Liou, Y. Xue, A. Eldering, A. Hall, Y. Chao,  R. Fovell, Q. Li, J. McWilliams 2008: Anthropogenic Climate Changes in California: Hydroclimate, Snowpack, and Santa Ana Winds, Fifth Annual Climate Change Research Conference, September 8-10, 2008, Sacramento, CA.
- **Kim, J., D. Waliser, R. Fovell, A. Hall, K. Liou, Y. Xue, J. McWilliams, Y. Chao, A. Eldering, Q. Li and S. Kapnick, 2008: A projection of the cold season hydroclimate in California in mid-21st century under the SRES-A1B emission scenario, Fifth Annual Climate Change Research Conference, September 8-10, 2008, Sacramento, CA.
- ** Waliser, D., J. Kim, Y. Xue, Chao, Y., A. Eldering, R. Fovell, A. Hall, Q. Li, K. Liou, J. McWilliams, S. Kapnick, R. Vasic, F. De Sale, and Y. Yu, 2008, Simulating the Sierra Nevada snowpack: The impact of snow albedo and multi-layer snow physics, Fifth Annual Climate Change Research Conference, September 8-10, 2008, Sacramento, CA.
- ** Also a contribution to the CEC’s and CEPA’s Biennial 2008 California Climate Change Report, in press.

**National**** ****Aeronautics and Space Administration**
**Jet Propulsion Laboratory**
- California Institute of Technology
- Pasadena, California
**www.nasa.gov**

- National Aeronautics and Space Administration

**Figure 1. **The cold-season snow-water equivalence (SWE) climatology for 1961-1980 in an NCAR CCSM3 simulation. Due to the lack of spatial resolution, the GCM does not capture the significant snow cover in the Sierra Nevada region.

**Benefits to NASA and JPL (or significance of results):**
- The investigators applied the JIFRESSE Regional Earth System Model (RESM) to an important issue regarding Climate Change and its impact/projection in  California.
- Results indicate that significant uncertainties exist in the IPCC AR4 GCM projections of snowpack for California associated with anthropogenic warming.  These will need to be reduced through via further investments in observations and modeling activities.
- The work has resulted in invited contribution to the 5th Annual California Climate Change Conference (Sep 08, Sacramento, CA) and the 2008 California Energy Commission’s and California Environmental Protection Agency’s Biennial Report on Climate Change and California.

**Figure 2. **The variation of snow albedo according to soot content (from Warren and Wiscombe  1980). Their theoretical study snows that black carbons within a snow layer can significant alter snow albedo, one of the major factors involved in determining the amount of snow during the cold season and snow ablation periods.

**Figure 4. **Two cold SWE climate change signals are constructed from two sets of climate change for the two domains. The SWE ratio between the future (2045-2054) and present (1971-1980) climatology differ significantly according to horizontal resolution. Note that areas above 2750m are not represented in the 36km resolution terrain.

**Figure 3. **Model domains used in the 36km (outer area) and 12km (inner area) runs. The innermost box indicates the Sierra Nevada region.

- Further examination of snowfall and snow depth reveals that the difference in the projected SWE sensitivity between the two simulations are not due to the differences in the snowfall sensitivity, but is caused by the differences in the snowfall amount between the two runs. Snow-albedo feedback that depends on the total amount of snow amplified the differences in snowfall to result in substantially different SWE sensitivity.

**Poster No. 08-D-10**

**Principal Investigator: Duane Waliser (3246)**
**J. Kim (UCLA), K-N Liou (UCLA), Y. Xue (UCLA), R. Fovell (UCLA), A. Hall (UCLA), **
**Q. Li (3286, UCLA), A. Eldering (3280), Y. Chao (3240), S. Saatchi (334H)**

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