is computed as
where T is the temperature, po
the reference pressure (1013.25 mb), p the pressure, R the gas constant for dry air
(287.04 J kg-1 K-1), and Cp the specific heat capacity of dry air at
constant pressure (1004.6 J kg-1 K-1).Last updated: 2008-03-12 by David Stepaniak (davestep@ucar.edu)\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\sBack to Documentation
The 23 standard pressure levels in JRA-25 in mb (or hPa) are, from lowest isobaric altitude to highest isobaric altitude in the atmosphere:
1000, 925, 850, 700, 600, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10, 7, 5, 3, 2, 1, 0.4
This is the ordering convention of the pressure level vertical coordinate in JRA-25. JRA pressure level variables are assigned interpolated values where isobaric surfaces dip below topography. There are no missing values. We do not have specific information about the below topography interpolation scheme used by JMA at this time.
The 20 standard isentropic (theta) levels in JRA-25 in K (Kelvin) are, from lowest isentropic altitude to highest isentropic altitude in the atmosphere:
270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 425, 450, 475, 550, 650, 750
This is the ordering convention of the theta level vertical coordinate in JRA-25. JRA theta level variables are assigned missing values (9.999e+20) where isentropic surfaces dip below topography — this occurs in the 8 lowest theta levels, i.e. 270, 280, 290, 300, 310, 320, 330, and 340 K.
For convenience, below we show the JRA-25 pressure and isentropic levels arranged relative to a standard atmosphere. JRA-25 pressure levels are shown in bold black digits. JRA-25 theta levels are shown in bold red digits. Note that the global average tropopause height is indicated ( in blue ~~~) as 12 kilometers — in practice the height of the tropopause varies between 8 kilometers (poles) and 17 kilometers (equator). A stratopause ( in green ~~~) at 50 kilometers is also shown, as well as an ozone mazimum near 25 kilometers.
For this representation of a standard atmosphere,
potential temperature is computed as
where T is the temperature, po
the reference pressure (1013.25 mb), p the pressure, R the gas constant for dry air
(287.04 J kg-1 K-1), and Cp the specific heat capacity of dry air at
constant pressure (1004.6 J kg-1 K-1).
-------------------------------------------------------------------------------------------------------------------
| | | Potential |
| Pressure | | Temperature |
Height | JRA-25 | Temperature | JRA-25 | Density
meters km feet mi | mb/hPa mb/hPa | K deg C deg F | K † K | kg m-3
------------------------------------- |----------------- |----------------------------- |--------------- |---------
- 80000 --- 80.0 -- 262467 --- 49.7 - | 0.010 -------- | 198.6 ---- -74.5 --- -102.1 | 5350.0 ------- | 0.00002
- 70000 --- 70.0 -- 229659 --- 43.5 - | 0.052 -------- | 219.5 ---- -53.6 --- -64.5 | 3691.6 ------- | 0.00008
- 60000 --- 60.0 -- 196850 --- 37.3 - | 0.220 -------- | 247.0 ---- -26.1 --- -15.0 | 2750.9 ------- | 0.00030
0.4
~ 50000 ~~~ 50.0 ~~ 164042 ~~~ 31.1 ~ | 0.798 ~~~~~~~~ | 270.6 ~~~~ -2.5 ~~~ +27.5 | 2085.5 ~~~~~~~ | 0.00100 ← Ave stratopause
1
- 45000 --- 45.0 -- 147638 --- 28.0 - | 1.491 -------- | 264.1 ---- -9.0 --- +15.8 | 1702.5 ------- | 0.00200
2
- 40000 --- 40.0 -- 131234 --- 24.9 - | 2.871 -------- | 250.3 ---- -22.8 --- -9.0 | 1338.1 ------- | 0.00400
3
5
- 35000 --- 35.0 -- 114829 --- 21.7 - | 5.746 -------- | 236.5 ---- -36.6 --- -33.9 | 1037.0 ------- | 0.00800
7
10
- 30000 --- 30.0 -- 98425 --- 18.6 - | 11.970 -------- | 226.5 ---- -46.6 --- -51.9 | 805.3 ------- | 0.01800
750
650
- 25000 --- 25.0 -- 82021 --- 15.5 - | 25.492 -------- | 221.5 ---- -51.6 --- -60.9 | 634.5 ------- | 0.04000 ← Ozone maximum
30 550
50
- 20000 --- 20.0 -- 65617 --- 12.4 - | 55.293 -------- | 216.6 ---- -56.5 --- -69.7 | 497.3 ------- | 0.08900
- 19000 --- 19.0 -- 62336 --- 11.8 - | 64.674 -------- | 216.6 ---- -56.5 --- -69.7 | 475.6 ------- | 0.10400
70 475
- 18000 --- 18.0 -- 59055 --- 11.2 - | 75.652 -------- | 216.6 ---- -56.5 --- -69.7 | 454.7 ------- | 0.12200
450
- 17000 --- 17.0 -- 55774 --- 10.6 - | 88.497 -------- | 216.6 ---- -56.5 --- -69.7 | 434.8 ------- | 0.14200
100 425
- 16000 --- 16.0 -- 52493 --- 9.9 - | 103.520 -------- | 216.6 ---- -56.5 --- -69.7 | 415.7 ------- | 0.16600
400
- 15000 --- 15.0 -- 49213 --- 9.3 - | 121.110 -------- | 216.6 ---- -56.5 --- -69.7 | 397.5 ------- | 0.19500
390
- 14000 --- 14.0 -- 45932 --- 8.7 - | 141.700 -------- | 216.6 ---- -56.5 --- -69.7 | 380.1 ------- | 0.22800
150 380
370
- 13000 --- 13.0 -- 42651 --- 8.1 - | 165.790 -------- | 216.6 ---- -56.5 --- -69.7 | 363.4 ------- | 0.26700
360
350
~ 12000 ~~~ 12.0 ~~ 39370 ~~~ 7.5 ~ | 193.990 ~~~~~~~~ | 216.6 ~~~~ -56.5 ~~~ -69.7 | 347.4 ~~~~~~~ | 0.31200 ← Ave tropopause
200 340
- 11000 --- 11.0 -- 36089 --- 6.8 - | 226.990 -------- | 216.7 ---- -56.4 --- -69.5 | 332.4 ------- | 0.36500
250 330
- 10000 --- 10.0 -- 32808 --- 6.2 - | 264.990 -------- | 223.2 ---- -49.9 --- -57.8 | 327.5 ------- | 0.41300
- 9500 --- 9.5 -- 31168 --- 5.9 - | 285.840 -------- | 226.5 ---- -46.6 --- -51.9 | 325.2 ------- | 0.44000
300
- 9000 --- 9.0 -- 29528 --- 5.6 - | 308.000 -------- | 229.7 ---- -43.4 --- -46.1 | 322.9 ------- | 0.46700
- 8848 --- 
Everest (8848 m, 29028 ft)
- 8500 --- 8.5 -- 27887 --- 5.3 - | 331.540 -------- | 232.9 ---- -40.2 --- -40.4 | 320.5 ------- | 0.49600
320
- 8000 --- 8.0 -- 26247 --- 5.0 - | 356.510 -------- | 236.2 ---- -36.9 --- -34.4 | 318.4 ------- | 0.52600
- 7500 --- 7.5 -- 24606 --- 4.7 - | 382.990 -------- | 239.4 ---- -33.7 --- -28.7 | 316.2 ------- | 0.55700
400
- 7000 --- 7.0 -- 22966 --- 4.3 - | 411.050 -------- | 242.7 ---- -30.4 --- -22.7 | 314.1 ------- | 0.59000
- 6500 --- 6.5 -- 21325 --- 4.0 - | 440.750 -------- | 245.9 ---- -27.2 --- -17.0 | 312.0 ------- | 0.62400
310
- 6000 --- 6.0 -- 19685 --- 3.7 - | 472.170 -------- | 249.1 ---- -24.0 --- -11.2 | 309.9 ------- | 0.66000
500
- 5500 --- 5.5 -- 18045 --- 3.4 - | 505.390 -------- | 252.4 ---- -20.7 --- -5.3 | 308.0 ------- | 0.69700
- 5000 --- 5.0 -- 16404 --- 3.1 - | 540.480 -------- | 255.6 ---- -17.5 --- +0.5 | 305.9 ------- | 0.73600
- 4500 --- 4.5 -- 14764 --- 2.8 - | 577.520 -------- | 258.9 ---- -14.2 --- +6.4 | 304.1 ------- | 0.77700
600
- 4000 --- 4.0 -- 13123 --- 2.5 - | 616.600 -------- | 262.1 ---- -11.0 --- +12.2 | 302.1 ------- | 0.81900
- 3500 --- 3.5 -- 11483 --- 2.2 - | 657.800 -------- | 265.4 ---- -7.7 --- +18.1 | 300.3 ------- | 0.86300
700 300
- 3000 --- 3.0 -- 9843 --- 1.9 - | 701.210 -------- | 268.6 ---- -4.5 --- +23.9 | 298.4 ------- | 0.90900
- 2500 --- 2.5 -- 8202 --- 1.6 - | 746.910 -------- | 271.9 ---- -1.2 --- +29.8 | 296.7 ------- | 0.95700
- 2000 --- 2.0 -- 6562 --- 1.2 - | 795.010 -------- | 275.1 ---- +2.0 --- +35.6 | 294.9 ------- | 1.00700
- 1500 --- 1.5 -- 4921 --- 0.9 - | 845.590 -------- | 278.4 ---- +5.3 --- +41.5 | 293.2 ------- | 1.05800
850
- 1000 --- 1.0 -- 3281 --- 0.6 - | 898.760 -------- | 281.6 ---- +8.5 --- +47.3 | 291.5 ------- | 1.11200
925 290
- 500 --- 0.5 -- 1640 --- 0.3 - | 954.610 -------- | 284.9 ---- +11.8 --- +53.2 | 289.8 ------- | 1.16700
1000
- 0 --- 0.0 -- 0 --- 0.0 - |1013.250 -------- | 288.1 ---- +15.0 --- +59.0 | 288.1 ------- | 1.22500 ← Surface
280
270
- -420 --- 
Dead Sea (-420 m, -1378 ft)
------------------------------------- |----------------- |----------------------------- |--------------- |---------
†
Potential temperature is computed as
where T is the temperature, po
the reference pressure (1013.25 mb), p the pressure, R the gas constant for dry air
(287.04 J kg-1 K-1), and Cp the specific heat capacity of dry air at
constant pressure (1004.6 J kg-1 K-1).
‡ Only the simplest complete photochemical cycle for ozone (Chapman cycle) is shown. M represents a third molecule needed to conserve momentum and energy in the recombination of O and O2.
Source of standard atmosphere (height, pressure, temperature, and density): Ahrens, C. Donald, 1994, Meteorology Today, An Introduction to Weather, Climate, and the Environment, Fifth Edition, West Publishing Company, St. Paul (Appendix H).