The time-varying microscale (TVM) model is a
microscale diagnostic model specifically designed to compute data for extremely high-resolution mapping (tens of meters to a few hundred meters) without the high computational costs of running a
mesoscale numerical weather prediction
Numerical weather prediction (NWP) uses mathematical models of the atmosphere and oceans to weather forecasting, predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of comput ...
(NWP) model such as
weather research and forecasting model (WRF).
TVM uses high-resolution
land surface
Terrain (), alternatively relief or topographical relief, is the dimension and shape of a given surface of land. In physical geography, terrain is the lay of the land. This is usually expressed in terms of the elevation, slope, and orientati ...
data to calculate the effects of microscale terrain features, near-surface roughness features, and other terrain blocking effects typically left unresolved by coarser mesoscale NWP models. Microscale terrain features are resolved using a
kinematic
In physics, kinematics studies the geometrical aspects of motion of physical objects independent of forces that set them in motion. Constrained motion such as linked machine parts are also described as kinematics.
Kinematics is concerned with s ...
terrain adjustment, near-surface roughness features are resolved using a log-profile surface roughness adjustment, and a
Froude number
In continuum mechanics, the Froude number (, after William Froude, ) is a dimensionless number defined as the ratio of the flow inertia to the external force field (the latter in many applications simply due to gravity). The Froude number is ba ...
adjustment is applied to calculate terrain-blocking effects on wind flow.
All of these effects are computed at each
time-step in the study period and based not only on
wind speed
In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer.
Wind spe ...
and
elevation
The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...
, but on quantities such as
wind direction
Wind direction is generally reported by the direction from which the wind originates. For example, a ''north'' or ''northerly'' wind blows from the north to the south; the exceptions are onshore winds (blowing onto the shore from the water) and ...
and thermodynamic properties of the lower
atmosphere
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...
. This enables a sophisticated time-varying
spatial analysis
Spatial analysis is any of the formal Scientific technique, techniques which study entities using their topological, geometric, or geographic properties, primarily used in Urban design, Urban Design. Spatial analysis includes a variety of techni ...
.
[{{Cite web, url=http://www.3tier.com/en/support/glossary/#tvm, title=Glossary of Technical Renewable Energy Terminology :: Support :: 3TIER]
References
Numerical climate and weather models