Frequently Asked Questions
Conventions Used in MM5 System
Time: All times used in MM5 modeling system are UTCs which
stands for Universal Time. It is the same as Greenwich Mean Time
(or GMT). To find out
what the local time at any model times, you need to know how far
ahead or behand GMT your local time is.
Latititude/Longitude: 0 degree is at Greenwich, England.
Positive longitude is eastward from Greenwich till dateline. Negative
longitude is westward
from Greenwich till dateline. Positive latitude is in the northern
hemisphere, and negative latitude is in the southern hemisphere.
Model winds: All gridded wind components (U and V) in the
model are with respect to model coordinate. This means the U component
is in x-direction
of the model, and V component in y-direction of the model. When
comparing model winds with station observations, winds need to be
rotated to earth
coordinate.
Model array indices: MM5 modeling system programs use array
indices I, J, and K, where I is in y direction, J in x direction,
and K in z direction.
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