Degree Days are measures of heating and cooling demand, essentially through a simplified representation of air temperature. A proxy for the amount of energy required to heat and cool infrastructure can be found taking the difference between an observed or forecast temperature and a base temperature. Below this base temperature, heating is required and above it some cooling is required. The base temperature for the United States is set at 18.3C. The larger the difference between vales of temperature and the base temperature, the greater the likely heating or cooling demand. Heating and cooling degree days can be combined (or added together) to produce a measure of demand across a wider area where there may be some heating and cooling required given temperature variation geographically. Degree days can also be accumulated over a period of days. Negative values of degree days are not possible.
Heating Degree Days = Actual/Forecast Temperature - Base Temperature (18.3C) >=0
Cooling Degree Days = Base Temperature (18.3C) - Actual/Forecast Temperature >=0Total Degree Days = Heating Degree Days + Cooling Degree Days
Here, the user can change the Degree Days data displayed on the map.
The following can be adjusted:
A. Elements
Choose from Total Degree Days, Heating Degree Days and Cooling Degree Days
B/C. Location Type
Choose the area over which the Degree Day calculations are displayed. Only those locations selected here will display any data on the map. This ranges from one value for the whole contiguous United States (CONUS), to smaller sub-divisions of Census Regions, Divisions, and individual States. Selecting any of these options will bring up an additional menu below to choose specific locations within that category (e.g. between Northeast, Midwest, South and West for the Census Regions category).
Location Selections:
A. Region selected and pinned to the top of menu
B. Region selected but not pinned
C. Region unselectedi. Select all regions
ii. Unselect all regions
iii. Invert the current selection of regions
D. ENS Type
When an ensemble forecast model is selected in the model matrix (see below), the form these data are displayed on the map can be changed here. The mean is displayed as default, but the median and mode of ensemble members can also be added.
E. Dates / Climate
Here, the user can determine the range of days available to be displayed on the map. A value for climatology on each date selected can also be toggled on and off here.
F. Obs
Actual Degree Days data back to 1990 is available here to add to the map. Multiple years can be displayed at once.
G.Options
One option here allows the user to toggle the 'Single Model Select' option on/off. When turned on, it is only possible to select one model or model run at a time in the model matrix (see below).
The model matrix is where the user can determine which forecast model's data is displayed on the map. Multiple model's data can be displayed at once. Simply tick a particular model run to display on the map, and untick to remove.
A. Expand matrix to include model runs back to 10 days
B. Toggle High/Low frequency
Click to switch between low frequency (multiples of 6 hours) or high frequency (greater resolution of model runs, down to hourly or 3-hourly model runs, including our MAGMA model.
C. List of available models
Selecting a model here will display the most recent two model runs
D. List of available model runs
Some models are not available at each time given. "LA" selects the latest available run for a given model. "PR" selects the model run before the latest available for a given model. Selecting "LA", "PR", or any of the available model run times will display all available data for that time.
For MAGMA, our in-house model, updates on a rolling basis as new model data comes in. The most recent data is available using "LA" or the most recent hour in the matrix. When a new hour arrives in the matrix (e.g. 06) then the data behind the previous step (i.e. 00) then is frozen with the current MAGMA data. Thus, the data included in a certain MAGMA snapshot does not necessarily include data from that hour's run of a certain model. For example, the "00" snapshot would not include the ECMWF EPS 00z data as that doesn't arrive until after 06:00GMT when the "00" snapshot is frozen. Instead, this data will be incorporated into the "06" MAGMA time slot.
E. Scroll back to older model runs
F. Example of model run unavailable
G. Example of unselelected but available model run
H. Example of selected model run
This product displays Degree Days data in map form; both recent years' observations and forecast model output. The content on the map is determined by options in the panel and model matrix, located to the left of the screen, and described in the relevant sections below. Those locations displayed on the map have their Degree Days colour coded in accordance with the key at the very top of the product screen. Only one day's data is displayed on the map at once.
Above the map itself, a slider (B) allows the user to move between specific day's data within the period selected in the panel (see below). A dropdown menu (A) to the left of the slider and arrow keys to the right (C) perform the same actions in slightly different ways. To the far right of this (D) there is a option to select a playback speed to scroll through each available days or remain static. Finally, a tick on/off box (E) allows for any animation playback to auto-reverse.
Hovering over a particular state, region or division will bring up a table (F) with the revelant data (as determined by selections in the panel, matrix, and time slider) refering to that specific location. The combined mean value of every selected model is also shown in this box. When no models are selected, the mean value of each year of selected observations is displayed instead.
There is also the option (G) to zoom in/out of the map.
To the bottom right of the screen, a small toolbar gives the user the option to view the map in full screen.