Updated January 23, 2015
All units are metric (mm, degrees C, cubic meters).
Missing values are marked with "nan," which stands for "not a number." Missing entries are due either to completely missing data or because time periods had insufficent data for an accurate calculation.
Here is a table showing which Stream Gages and SNOTEL stations are in each geographic zone - Download Here
A map of these stations and gages is here.
Normalization Procedure
1. For each stream gage or SNOTEL, separately calculate the mean and standard deviation for each parameter during the period spanning water years 1993 - 1994 through 2012-2013. These are defined as "mean" and "sd."
2. For each stream gage or SNOTEL, separately calculate the z value as z = (x-mean) / sd for each parameter for each water year, where x = the annual value for a parameter at a specific gage / SNOTEL. This results in normalized time series for each gage / SNOTEL that are all on a common scale of measure.
3. To find the zone or "overall" mean for a particular parameter for a particular water year, average all the z-scores available in that year for that parameter. The zonal z values appear in the columns labelled "overall_{parameter} in the normalized files below."
4. Stations or gages that do not have complete data during the reference period 1993 - 1994 through 2012 - 2013 (stations with short or poor quality records) have been excluded from normalization. You will notice that normalized values for these stations have been all replaced with "nan." This is to ensure that the same number of gages / stations were used to calculate the overall zone averages and sd (step 2) for each year. This restriction was relaxed for the SNOTEL monthly Tmax, Tmin, and Precip files presented below because too many SNOTEL stations were eliminated, and upon examination, it was found that each station only had a handful of missing months. We can relax this condition for all files, but exploratory graphs show that it produces jump or discontinuous time series that seem less likely to reveal true patterns.
Notice that "peak date" and other non-numeric fields cannot be normalized because they are expressed as calendar references, e.g. 6/01/1958. These columns are all replaced with "nan" in the normalized files, but there are numeric equivalents that have been normalized. For example, stream peak dates are available numerically in the variable "peak_index," which is the numbered day of the water year at which peak occurred.
Files below that have been normalized for "all stations" have "overall" columns that have been averaged across all the stations available in the study. Files that are normalized for a particular zone have overall columns that have been averaged across only the stations / gages in a sub-basin. In other words, the individual normalized time series will be the same in all stations vs. zone normalized files, and only the overall averages will differ.
**DEGREES F**
1. Tmin - Download Here.
2. Tmax - Download Here.
**Degrees F **
1. Tmin - monthly and annual - Download Here
2. Tmax- monthly and annual - Download Here
3. Tmin - seasonal - Download Here
4. Tmax - seasonal - Download Here
1a. Annual Snow Statistics, all stations
- Download
Here
1b. Normalized Annual Snow Statistics for all stations - Download Here
1c. Normalized Annual Snow Statistics for each zone - Zone 1 Zone 2 Zone 3 Zone 4
Description
For each water year at each station in the GYA, the following variables are reported:
Peak Snow Water Equivalent (PWE) - millimeters
Peak snow day - day on which peak SWE occurred expressed as number of days since the start of the water year (October 1)
Peak snow date - day on which peak swe occurred expressed as year / month
Winter Length - Number of days with Snow Water Equivalent (SWE) greater than zero
Melt - Number of days between peak SWE and complete melt
2a. April 1 SWE, all stations - Download Here
2b. Normalized April 1 SWE, all stations - Download Here
2c. Normalized April 1 SWE for each zone - Zone 1 Zone 2 Zone 3 Zone 4
Description
Snow water equivalent (mm) on April 1 for each year at each station.
3a. Monthly peak Snow Water Equivalent, all stations - Download Here
3b. Normalized monthly peak SWE, all stations
- Download
Here
3c. Normalized monthly peak SWE for each zone - Zone 1 Zone 2 Zone 3 Zone 4
Description
For each month during each water year at each station, Peak Snow Water Equivalent (mm). Months are indicated in the header as numbers. For example, gunsight_pass_01 is the PWE for January at the Gunsight Pass SNOTEL station.
4. SNOTEL Reconnaissance Drought Index - Download Here
These values are already normalized. See the references below for details.
Description
For each water year at each station, the Normalized Reconnaissance Drought Index.
Information on the Reconnaissance Drought Index is available in this article. Evapotranspiration calculations used in the index are based on the Penman Montieth Equation using methods described here.
5a. Monthly Tmax, Tmin, Precip totals / averages for all stations : Tmax: Download Here Tmin: Download Here Precip: Download Here
5b. Normalized monthly Tmax, Tmin, and Precip
for all stations: Tmax: Download
Here Tmin: Download
Here Precip: Download
Here
5c. Normalized monthly summaries for each zone:
Tmax: Zone 1 Zone 2 Zone 3 Zone 4
Tmin: Zone 1 Zone 2 Zone 3 Zone 4
Precip: Zone 1 Zone 2 Zone 3 Zone 4
Description
For each month at each station, Average Tmax (Degrees C), Average Tmin (Degrees C), and Precip (mm). Months that have more than 3 days of missing precipitation measurements are marked as missing. Months with more than 5 days of missing temperature measurements are marked as missing. Tmax = Daily maximum temperature. Tmin = daily minimum temperature.
6a. Day of
complete melt out (zero swe) for each water year, expressed as number
of days after October 1. All stations - Download
Here
6b. Day of
melt out for each zone (these are already on the same scale so don't
need normalized): Zone
1 Zone
2 Zone
3 Zone
4
1. Annual Stream Statistics - Download Here
2. Normalized (z-score) stream statistics for all gages - Download Here
3. Normalized (z-score) stream statistics for each zone - Zone 1 Zone 2 Zone 3 Zone 4
More
information on the normalization procedure appears below.
Description
For each water year at each station, the following variables are presented:
- StationName_median_# (e.g. soda_boundary_01)= Median flow value (cubic meters per second) for the numbered month. Months are numbered 1 - 12
- StationName_min_# = Minimum daily flow (Cubic meters per second) for the numbered month. Months are numbered 1 - 12.
- date_half_disch = Calendar date at which centroid of flow was reached
- index_half_disch = Day of water year (number of days after October 1) on which centroid was reached
- height_half_disch = flow rate (cubic meters per second) on the date that centroid of flow was reached
-peak_date = Calendar date of peak flow
- peak_index = Day of water year (number of days after October 1) on which peak flow occurred
-peak_cms = Peak Flow (Cubic meters per second)
- min_date, min_index, min_cms = Same as the last 3 above but for minimum flow during each water year
- total_vol = total volume (cubic meters) of water for each water year
-peak_minus_min = Peak flow rate - min flow rate
-moving_25th_percentile_flow = 25th percentile flow (cubic meters per second) for the 10 year period including the water year listed and the previous 9 years.
-days_below_moving_25th = # days in the listed water year that had flow below the moving 25th percentile
-days_below_recent_25th = # days below the 25th percentile flow during the period 1981 - 2010.
-gradient_index = A hydrograph "spikiness" index which is calculated as the sum of all the first derivative values in a water year
-days_above_recent_winter_90th = The number of days during November - March in each water year that exceeds the November - March 90th percentile flow. 90th Percentile for Nov - Mar is calculated during the years 2001 - 2010
-days_below_recent_summer_10th = The numbers of days during July - September in each water year that are below the 10th percentile flow for July - September. 10th percentile calculated over 2001 - 2010.
-days_below_recent_summer_25th = The number of days during July - September in each water year that are below the 25th percentile flow for July - September. 25th percentile is calculated over 2001 - 2010.
-est_vals = The number of flow measurements in each water year that are estimated (have data flag e). Estimated values USUALLY occur when there is ice on the gage.