113 lines
3.6 KiB
Text
113 lines
3.6 KiB
Text
|
National Environmental Public Health Tracking Network
|
||
|
|
Global Horizontal Irradiance (GHI) Metadata
|
||
|
|
|
||
|
|
|
||
|
|
Publication Date
|
||
|
|
|
||
|
|
|
||
|
|
11/07/2018
|
||
|
|
|
||
|
|
|
||
|
|
Background
|
||
|
|
|
||
|
|
|
||
|
|
Global Horizontal Irradiance (GHI) is the total amount of shortwave radiation received by
|
||
|
|
a horizontal surface from above. The available county-level data show the temporal and
|
||
|
|
spatial trends of population-weighted irradiance levels throughout the contiguous
|
||
|
|
United States from 1991 to 2012.
|
||
|
|
|
||
|
|
|
||
|
|
The GHI data is provided by the Environmental Remote Sensing group at the Rollins
|
||
|
|
School of Public Health at Emory University, led by Prof. Yang Liu. The 1991-1997 data
|
||
|
|
are calculated based on the GHI data from the National Solar Radiation Data Base
|
||
|
|
(NSRDB), and the 1998-2012 data are calculated based on the GHI data from
|
||
|
|
SolarAnywhere irradiance data.
|
||
|
|
|
||
|
|
|
||
|
|
Data Values
|
||
|
|
|
||
|
|
|
||
|
|
Each record describes daily population-weighted GHI value in one county of a given
|
||
|
|
state. The unit is Wh/m2.
|
||
|
|
|
||
|
|
|
||
|
|
The following are included in each file:
|
||
|
|
STATEFIPS: FIPS codes for states
|
||
|
|
|
||
|
|
COUNTYFIPS: FIPS codes for counties
|
||
|
|
|
||
|
|
YEAR: Year
|
||
|
|
|
||
|
|
MONTH: Month of the year, from 1-12
|
||
|
|
|
||
|
|
DAY: Day of the month, from 1-31
|
||
|
|
|
||
|
|
GHI: County-level population weighted daily GHI
|
||
|
|
|
||
|
|
|
||
|
|
NAs in the dataset appear as missing values; these refer to no valid data and are caused
|
||
|
|
by invalid retrievals from NSRDB or SolarAnywhere. We suggest to treat NAs as missing.
|
||
|
|
|
||
|
|
|
||
|
|
Geographic Scale
|
||
|
|
|
||
|
|
|
||
|
|
All states in the contiguous United States by county
|
||
|
|
|
||
|
|
|
||
|
|
& Scope
|
||
|
|
|
||
|
|
Time Period January 1, 1991 — December 31, 2012
|
||
|
|
|
||
|
|
Raw Data Part 1. Data based on NSRDB solar data (1991-1997):
|
||
|
|
|
||
|
|
Processing Daily GHI values were calculated from original hourly METSTAT modeled GHI values on
|
||
|
|
|
||
|
|
|
||
|
|
NSRDB sites. Daily files were produced, each containing daily GHI values of all NSRDB
|
||
|
|
sites on U.S. continent. Universal Kriging (UK) with external trend (elevation) were
|
||
|
|
employed to interpolate GHI values to centers of population tracts (from United States
|
||
|
|
Census Bureau, https://www.census.gov/geo/reference/centersofpop.html) based on
|
||
|
|
daily NSRDB GHI data. The max distance for UK was set as 500 kilometers. Therefore, NA
|
||
|
|
was given if UK failed at the centroids of tracts. Population weighted daily GHI values
|
||
|
|
were then calculated in county level.
|
||
|
|
|
||
|
|
|
||
|
|
Part 2. Data based on SUNY solar data (1998-2012):
|
||
|
|
|
||
|
|
Daily GHI values were calculated from original hourly GHI values on SUNY grids with 10
|
||
|
|
km x 10 km resolution; valid daily GHI values were calculated by summing all 24 valid
|
||
|
|
hourly GHI values within the day. Otherwise, daily GHI value was marked as NA. Daily
|
||
|
|
GHI of one SUNY grid was assigned to a population census tract if the center of tract fell
|
||
|
|
into this SUNY grid. Population weighted daily GHI values were calculated at the county
|
||
|
|
level.
|
||
|
|
|
||
|
|
|
||
|
|
Part 3. Combine county-level population weighted GHI data from NSRDB and
|
||
|
|
SolarAnywhere
|
||
|
|
|
||
|
|
Time trends of county-level population-weighted GHI based on NSRDB and SUNY
|
||
|
|
products in 1998-2005 were compared, and excellent agreement was found between
|
||
|
|
the two sets. Therefore, time-series daily population-weighted GHI data on county level
|
||
|
|
was produced by using NSRDB-based data for 1991-1997, and using SolarAnywhere-
|
||
|
|
based data for 1998-2012.
|
||
|
|
|
||
|
|
|
||
|
|
No values were omitted from the original dataset. All missing data were caused by failed
|
||
|
|
or invalid retrievals in the original dataset. Overall, 8,036 daily files were produced
|
||
|
|
during the study period (8,036 days in total).
|
||
|
|
|
||
|
|
|
||
|
|
Additional
|
||
|
|
Information
|
||
|
|
|
||
|
|
|
||
|
|
Renewable Resource Data Center. National solar radiation data base.
|
||
|
|
http://rredc.nrel.gov/solar/old_data/nsrdb
|
||
|
|
|
||
|
|
|
||
|
|
SolarAnywhere. Available datasets and geographic coverage.
|
||
|
|
https://www.solaranywhere.com/validation/data/datasets
|
||
|
|
|
||
|
|
|