1. Selecting the initial parameters
    First you must select some of the starting parameters you want calculated into your map.  These include: Temperature Change, Melt Rate, Snow Density, and Precipitation.  Each are explained below.  If you do not type in any specific parameters, the program will automatically select default numbers for each of the fields.  Default parameters are listed to the right of the input box.

Temperature Change: This represents the number in degrees C of global temperature change. Can be either a positive (warming) or a negative (cooling) value. Default setting is 0 deg. C.

Melt Rate: This is the rate at which snow calculated on the map melts at, and is calculated in mm/positive degree day, or pdd (see below what a pdd is).  Default setting is 5mm/pdd

Snow Density: Snow is less dense than water.  The precipitation data used by the model are reported in millimeters water equivalence. The snow density term is used in the conversion of some precipitation amount to a snow depth by the equation: Snow Depth = Precipitation Amount / Snow Density.  For example, given a snow density of 50%, a snow depth of 1 meter would result from 0.5 meters of precipitation in water equivalence.  Default setting is 30%.

Precipitation: This represents a percentage with respect to the average modern precipitation value.  For example, 100% means that the input precipitation is unaltered in the mass balance calculation.  Conversly, 200% would afford a doubling of the input precipitation amount.  Default setting is 100%.
2. Selecting the Map
    Next, you must choose which map you want to be shown.  There are currently six different maps to choose from.
3. Choosing the Output
    Thirdly, you must select which output is displayed on the chosen map.  There are a total of seven different outputs to choose from.  The default selection is Mass Balance.  It should be noted that for the Temperature and Precipitation outputs, you can select which month you would like to view.  Simply select the month you want to show to the right of the Output box.  Default selection for this is the Annual data.  Below are descriptions of each of the outputs.

Snow Mass Balance: This is the amount of leftover snow after the itegration of the pdd's from the summer melting season.  Positive values represent the amount of snow leftover, whereas negative values indicate the amount of "extra snow" that particular region could have melted.  For example, if a mass balance of -25 meters means that the area had enough energy from it's total amount of pdd's to melt another 25 meters of snow.  Units are in meters.

Snow Depth: This shows the total depth of snow over an annual basis. Units are in meters.

Positive Degree Days (pdd): This is the total number of "days" in which the temperature was above 0 deg. C.  If a days average temperature was 1 deg. C, this would be one pdd.  If a days average temperature was 5 deg. C, then that day would have 5 pdd.  This output calculates the total amount of pdd's over the course of a year.  Units are in days.

Temperature: This is the average temperature over the course of the selected month.  Units in deg. C.

Precipitation: The total amount of precipitation (in water equivalent) over the course of the selected month. Units are in millimeters.

Topography: This shows the topography of the given map area.  Units are in meters.

Environment: This output shows the different environments based on temperature and precipitation data. Below is a list of the all the environments calculated by the program.

Snow (SN)
Dry Boreal Forest (DBF) Low or Mid Latitude Desert (ED)
Polar Desert (PD) Temperate Rainforest(TRF) Steppe (S)
Maritime Polar (MSP) Humid Boreal Forest (HBF) Tropical Rainforest (TRF)
Dry Tundra or Alpine (DTA) Mixed Boreal Forest (MF) Water (W)
Humid Tundra or Alpine (HTA) Broadleaf Forest (BLF)

4. Click the Start button
    After choosing the different parameters, simply click the Start button at the bottom and enjoy!

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University of Maine | Department of Earth Sciences | Climate Change Institute
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