Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation...
-
date post
20-Dec-2015 -
Category
Documents
-
view
219 -
download
1
Transcript of Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation...
![Page 1: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/1.jpg)
Mel Kunkel & Jen Pierce
Boise State University
Climatic Indices: Predictors of Idaho's Precipitation
and Streamflow
![Page 2: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/2.jpg)
Outline
• Reconstructing Timing of Past Snowmelt
• Linking Climate Indices to the timing of snowmelt, snow accumulation and total precipitation
• The next steps…….
![Page 3: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/3.jpg)
Reconstructing Timing of Past Snowmelt
• Purpose: Develop a repeatable technique for reconstructing past timing of snowmelt in Idaho to assess how past snowpacks have responded to oceanic and atmospheric influences --- this requires long term records.
![Page 4: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/4.jpg)
Reconstructing Timing of Past Snowmelt
• SNOTEL/Snow Course:Daily SNOTEL and monthly snow course SWE data
is readily available from the NRCS online. NRCS snow course data (many from the 1930s) provides long-term monthly SWE readings while SNOTEL data provides detailed daily snow depth and SWE measurements, but in most cases these records only exist since the early 1980s.
There are over 350 SNOTEL and snow course (current and discontinued) sites located within the Idaho watershed.
![Page 5: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/5.jpg)
Reconstructing Timing of Past Snowmelt
• SNOTEL/Snow Course:Recognizing that the NRCS emplaced SNOTEL
and snow course sites specifically to assist in forecasting the water supply of the western United States, we acknowledge that they may not be representative of the entire watershed.
![Page 6: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/6.jpg)
Reconstructing Timing of Past Snowmelt
• Hydro-Climatic Data Network (HCDN): The U.S. Geological Survey (USGS) maintains the largest collection of stream gages in the United States; these gage records form the basis of the HCDN. Use of the HDCN for climate studies is well established (e.g. Dettinger and Cayan 1995; Cayan et al. 2001; Stewart et al. 2005; Jefferson et al. 2006; Barnett et al. 2008; Levi 2008).
• Since HCDN streamflow records are relatively free of anthropogenic influences (Slack and Landwehr 1992), variations in streamflow in the HCDN basins are likely caused by changes in climate or basin characteristics rather than dam-related flow regulation or other anthropogenically-induced change
![Page 7: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/7.jpg)
Reconstructing Timing of Past Snowmelt
• Selecting suitable paired stream gage and SNOTEL site was critical to accurately reconstructing the timing of past snowmelt.
• We selected USGS gage stations and SNOTEL sites by spatially overlaying gage positions, SNOTEL positions, and stream/river information. We then identified gage sites and SNOTEL sites that were within the same drainage basin, and relatively close together.
![Page 8: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/8.jpg)
Reconstructing Timing of Past Snowmelt
• Through this selection process, we identified 28 unregulated streams as candidates for use in extending the SNOTEL data sets.
• Other unregulated streams with gage sites lacked SNOTEL sites within their immediate drainages and were not used for this study.
![Page 9: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/9.jpg)
![Page 10: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/10.jpg)
Reconstructing Timing of Past Snowmelt
• Conducted a Short Term Fourier Transform on selected site discharge.
• STFT transforms the annual discharge data into a spectral signal that varies in shape and magnitude over time, reflecting changes in discharge.
• We developed procedures to use the results of the STFT to reconstruct the timing of snowmelt based on the temporal distance of final snowmelt from existing SNOTEL data from the spectral peak (peak spring discharge).
![Page 11: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/11.jpg)
An example of a single spectral peak where the final snowmelt date always appears two timing points right of the spectral peak. (Trinity Mountain SNOTEL and Boise River)
![Page 12: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/12.jpg)
An example of twin spectral. The timing point for this site always reads three timing points to the left of the left hand center of timing. (Meadow Lake SNOTEL and Lemhi River)
![Page 13: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/13.jpg)
Reconstructing Timing of Past Snowmelt
![Page 14: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/14.jpg)
Reconstructing Timing of Past Snowmelt
![Page 15: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/15.jpg)
Reconstructing Timing of Past Snowmelt
• Results:• Reconstructions of snowmelt dates from these 19
sites extend records of the estimated timing of snowmelt back 42–97 years, >1100 reconstructions.
• None of the 419 compared reconstructed final snowmelt dates deviated from the actual snowmelt date by more 4 days ∼95% of the time and ±7 days 100%
• Assuming that the relationship between discharge and timing of snowmelt established using known data holds true for the earlier part of the record, we therefore assume reconstructions of the timing of snowmelt using this method are also within ±7 days.
![Page 16: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/16.jpg)
Linking Climate Indices to the timing of snowmelt, snow accumulation and
total precipitation
![Page 17: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/17.jpg)
Linking Climate Indices
• Use past records of the timing of snowmelt, max snow accumulation, dates of max accumulation and total precipitation
• Indices of interest– ENSO (TNI/MEI)– Arctic Oscillation (AO)– Pacific Decadal Oscillation (PDO)– And others
![Page 18: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/18.jpg)
Linking Climate Indices
• 1999 – La Nina and Positive AO
![Page 19: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/19.jpg)
Linking Climate IndicesMax SWE
Total Precip
Max SWE date
FinalSnowmelt
date
Date more than1.5 weeks later than normal
Date more than 1.5 weeks earlierthan normal
1999
10% or greaterabove normal
10% or greaterbelow normal
![Page 20: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/20.jpg)
Linking Climate Indices
• 1999 – Greater than normal precipitation Later than normal final
snowmelt La Nina and Positive AO
• 1987 – El Nino and Negative AO
![Page 21: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/21.jpg)
Linking Climate IndicesMax SWE
Total Precip
Max SWE date
FinalSnowmelt
date
Date more than1.5 weeks later than normal
Date more than 1.5 weeks earlierthan normal
1987
10% or greaterabove normal
10% or greaterbelow normal
![Page 22: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/22.jpg)
Linking Climate Indices
• 1999 – Greater than normal precipitation Later than normal final
snowmelt La Nina and Positive AO
• 1987 – Lower than normal precipitation Earlier than normal final
snowmelt El Nino and Negative AO
• 1991 – El Nino and Positive AO
![Page 23: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/23.jpg)
Linking Climate IndicesMax SWE
Total Precip
Max SWE date
FinalSnowmelt
date
Date more than1.5 weeks later than normal
Date more than 1.5 weeks earlierthan normal
1991
10% or greaterabove normal
10% or greaterbelow normal
![Page 24: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/24.jpg)
Linking Climate Indices
• 1999 – Greater than normal precipitation Later than normal final snowmelt La Nina and Positive AO
• 1987 – Lower than normal precipitation Earlier than normal final snowmelt El Nino and Negative AO
• 1991 – Regional variations in precipitation Regional variation in final
snowmeltEl Nino and Positive AO
• 1998 – La Nina and Negative AO
![Page 25: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/25.jpg)
Linking Climate IndicesMax SWE
Total Precip
Max SWE date
FinalSnowmelt
date
Date more than1.5 weeks later than normal
Date more than 1.5 weeks earlierthan normal
1998
10% or greaterabove normal
10% or greaterbelow normal
![Page 26: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/26.jpg)
Linking Climate Indices• 1999 – Greater than normal precipitation
Later than normal final snowmelt La Nina and Positive AO
• 1987 – Lower than normal precipitation Earlier than normal final snowmelt El Nino and Negative AO
• 1991 – Regional variations in precipitation Regional variation in final snowmelt
El Nino and Positive AO• 1998 – Regional variations in precipitation
Regional variation in final snowmelt La Nina and Negative AO
![Page 27: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/27.jpg)
The Next Step……
• Continue to use developed Empirical Rules of Thumb on how regional snow and precipitation responds under similar combined conditions to enhance understanding of physical processes driving Idaho weather
• Continued development of mixed statistical and physically based models for Idaho’s regional and watershed level snow, precipitation and streamflow
![Page 28: Mel Kunkel & Jen Pierce Boise State University Climatic Indices: Predictors of Idaho's Precipitation and Streamflow.](https://reader031.fdocuments.in/reader031/viewer/2022033104/56649d425503460f94a1e1c8/html5/thumbnails/28.jpg)
Thanks!!