Table 1-3.—MRS Mandatory Levels Printout (LIST)
P r e s s
H g h t
T e m p
H u m
T d
d d
f
R I
M R I
h P a
g p m
C
%
C
d e g
kts
1000.0
431
/ / / / /
/ / /
/ / / / /
/ / /
/ / / /
/ / /
/ / / /
925.0
606
6.1
95
5.2
273
13.0
298
395
850.0
1303
1.5
8 5
-0.7
277
15.4
268
395
700.0
2837
-8.8
9 4
-9.6
254
8.6
2 1
6 6 6
600.0
5360
-26.4
5 8
-32.2
190
9.3
160
1001
400.0
6927
- 4 0 . 1
5 0
- 4 6 . 6
159
6 . 0
1 3 4
1221
300.0
8829
- 5 1 . 4
2 3
- 6 3 . 5
258
1 0 . 1
1 0 5
1491
2 5 0 . 0
10022
- 4 6 . 3
2
- 7 6 . 8
281
2 4 . 3
8 6
1659
2 0 0 . 0
11510
-44.5
1
- 8 0 . 0
278
2 9 . 9
6 8
1875
1 5 0 . 0
13429
- 4 5 . 7
1
- 8 0 . 8
2 7 4
3 2 . 1
5 1
2160
1 0 0 . 0
16116
-47.1
1
- 8 1 . 8
270
3 1 . 3
34
2565
7 0 . 0
18467
-50.4
1
- 8 4 . 1
2 7 1
3 0 . 5
24
2924
5 0 . 0
20662
-52.7
1
- 8 5 . 7
279
2 4 . 5
18
3262
3 0 . 0
23980
/ / / / /
/ / /
/ / / / /
/ / /
/ / / /
/ / /
/ / / /
Significant Temperature and Humidity Levels
The following criteria apply to the selection of
significant levels for temperature and humidity
changes. They are considered mandatory and must be
reported whenever observed. The MRS is programmed
to automatically select these levels.
Surface level and the highest level observed
At least 1 level between 110 and 100 hPa
Freezing level(s)
The tropopause
Bases and tops of all temperature inversions
(layer in which the temperature increases with height)
and bases and tops of all isothermal layers (layer in
which the temperature does not change with height) that
are 30-hPa or more thick and located below 300-hPa
level or below the tropopause
Bases and tops of all temperature inversions in
which the temperature changes by 2.5°C or more below
the 300-hPa level or the tropopause
Bases and tops of all humidity inversions (layer
in which the humidity or dew-point temperature
increases with height) in which the relative humidity
increases by at least 20% when located below the 300-
hPa level or the tropopause
Bases and tops for all layers thicker than 20 hPa
in which temperature or humidity data is missing
The bases and tops of all layers delineated as
doubtful (must be entered manually)
The purpose of selecting significant levels is to
ensure that the vertical profile of the atmosphere is
accurately represented.
When you plot significant
levels on a diagram (such as the Skew T, Log P),
connecting each plotted temperature and dew-point
temperature with a straight line will provide a good
representation of the actual temperature and moisture
changes in the atmosphere.
The manual rawinsonde system operator must
select levels based on the same criteria listed above in
addition to other levels outlined in the FMH-3. As
previously stated. the MRS automatically selects
“mandatory” significant levels and “supplemental”
significant levels to ensure that these criteria are met.
But the MRS operator must review the selected levels to
ensure that the system is operating correctly.
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