Image Metadata File

Person Submitting Metadata/Point of Contact:

Name: Laura Stevens
Physical Address: 151 Patton Ave Asheville, NC 28801
Organization: CICSNC
Email:
Phone:

Image Info:

Image Title:
Time series of an index for the occurrence of heat waves and cold waves
Image Description:
Time series of an index for the occurrence of heat waves (top) and cold waves (bottom), defined as 4-day periods that are hotter and colder, respectively, than the threshold for a 1 in 5-year recurrence, for the Southwest region. The dashed line is a linear fit. Based on daily COOP data from long-term stations in the National Climatic Data Center’s Global Historical Climate Network data set. Only stations with less than 10% missing daily temperature data for the period 1895-2011 are used in this analysis. Events are first identified for each individual station by ranking all 4-day period mean temperature values and choosing the highest (heat waves) and lowest (cold waves) non-overlapping N/5 events, where N is the number of years of data for that particular station. Then, event numbers for each year are averaged for all stations in each 1x1° grid box. Finally, a regional average is determined by averaging the values for the individual grid boxes. This regional average is the index. There is a statistically significant upward trend in heat waves. The most intense heat waves occurred in the 1930s and 2000s.There is a statistically significant downward trend in cold waves and the number of intense cold wave events has been low during the last 15 years.
Attributes (variables name, description and units):
Heat wave index; Cold wave index (/ year)
Temporal domain:
Start Time: 1895-01-01 00:00:00.0
End Time: 2011-12-31 00:00:00.0
Spatial domain:
Max latitude: 41.9375
Min latitude: 31.4375
Max longitude: -102.063
Min longitude: -124.313
Keywords:
Southwest, Observed, USGHCN Daily, Temperature
Usage Limitations/Constraints:
Citation of image source:

Panels within image: 2

Top:
Image Title:
Heat waves
Bottom:
Image Title:
Cold waves

Image Creation:

Who created the image:
Name: Laura Stevens
Physical Address: 151 Patton Ave Asheville, NC 28801
Organization: CICSNC
Email:
Phone:
When was image created (YYYY-MM-DD): 2012-08-15 00:00:00.0

Data Sources:

Dataset #1
Dataset Name: USGHCN Daily
Dataset Version:
Dataset Description: Global Historical Climatology Network - Daily
Dataset ID:
Dataset Release/Publication Date:
Affiliated Organization Name and Role: NOAA NCDC/Russ Vose
Date Accessed: 2011-06-06 00:00:00.0
Dataset Location (ftp, URL, etc): ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/
Data qualifier (QA/QC, etc):
The denominator of the scale of the source/output:
Spatial Reference system used by the source/output:
Citation to metadata:
Description of the scope of a resource, quality report, or process:
Spatial Extent of the source/output (polygon, box or region name): National
Temporal extent of the source/output: 1895-01-01 to 2011-12-31
Vertical extent of the source/output:
Identifier of the processing level of the source/input:
Spatial resolution of the source/output: 1 km

Processes:

Process #1
Input(s):
Step(s):
  • The data set is GHCN-Daily. Stations were selected by examining each station in the entire data base with a USCxxxxxxxx identifier. Only stations with less than 10% missing daily temperature data for the period 1895-2011 are used in this analysis. Days when the temperature data had a quality flag were considered missing. Daily mean temperature is the average of the maximum temperature and minimum temperature. Events are first identified for each individual station by ranking all 4-day period mean temperature values and choosing the highest (heat waves) and lowest (cold waves) non-overlapping N/5 events, where N is the number of years of data for that particular station. We require that a minimum two-day period separate all events. Thus, for example, if the highest 4-day period is July 14-17, 2011, the periods of July 12-13 and July 18-19, 2011 are excluded from being a part of lower-ranked events. A year was not included in this analysis if there were less than 300 non-missing temperature values in that year. After determining events for each station, event numbers for each year are averaged for all stations in each 1x1° grid box. Finally, a regional average is determined by averaging the values for the individual grid boxes. This regional average is the index.
Output(s):
Software:
Environment(s):
Additional Comments:

References: