# CMAQ model integration step size

**URL:** <https://forum.cmascenter.org/t/cmaq-model-integration-step-size/1791>\
**Category:** CMAQ\
**Created:** [September 22, 2020, 6:16am UTC](https://forum.cmascenter.org/t/cmaq-model-integration-step-size/1791 "2020-09-22T06:16:13Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![hml](https://avatars.discourse-cdn.com/v4/letter/h/9fc29f/32.png) [@hml](https://forum.cmascenter.org/u/hml)\
**Post date:** [September 22, 2020, 6:16am UTC](https://forum.cmascenter.org/t/cmaq-model-integration-step-size/1791/1 "2020-09-22T06:16:13Z")

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When I run the Domain d03 in CMAQ mode, the cmaq mode reports an error if the integration step length is too large。Is it a meteorological parameter? Who can solve this problem，please！

The following is the error message recorded in the log:  
After NEXTIME: returned JDATE, JTIME 2020158 082400

```
 Maximum eddy diffusivity of: 1000.0 (m**2/sec)
 at col, row, layer: 1, 1, 4
 corresponding to a free tropospheric wind shear of: 1.15848E-03 (/sec),
                        a bulk Richardson Number of: 16.701 ,
 and pot. temps. in layer and layer+1: 313.15 313.27

```

after VDIFF G 2.3143053E-01 A 2.6396239E+09 N 6.3370252E-03  
after COUPLE G 2.2692888E+03 A 4.5091708E+13 N 6.2045349E+01  
after HADV G 2.2726829E+03 A 4.4230098E+13 N 6.2261684E+01  
zadv col row ff dt iter Mlvl Mvel Mvel1  
zzzz 10 4 8.219E-02 10.000 36 2 -5.75E-04 -4.70E-04  
zzz2 1 147.3810  
zzz2 2 326.2950  
zzz2 3 958.7557  
zzz2 4 2055.576  
zzz2 5 3460.824  
zzz2 6 4873.692  
zzz2 7 6562.991  
zzz2 8 8529.901  
zzz2 9 11598.25  
zzz2 10 13713.00  
zzz2 11 15253.05  
zzz2 12 14590.37  
zzz2 13 9361.908  
zzz2 14 9757.228  
after ZADV G 2.2630393E+03 A 4.4134459E+13 N 6.1639381E+01

```
 H-eddy DT & integration steps: 3.6000000E+02 1

```

after HDIFF G 2.2630391E+03 A 4.4134463E+13 N 6.1639389E+01  
after DECOUPLE G 2.3079310E-01 A 2.6125225E+09 N 6.2955916E-03  
after PING G 2.3079310E-01 A 2.6125225E+09 N 6.2955916E-03  
after CLDPROC G 2.3078959E-01 A 2.6123315E+09 N 6.2953741E-03

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**Author:** ![lizadams](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@lizadams](https://forum.cmascenter.org/u/lizadams)\
**Post date:** [October 2, 2020, 8:46pm UTC](https://forum.cmascenter.org/t/cmaq-model-integration-step-size/1791/2 "2020-10-02T20:46:50Z")

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I’ve tagged your issue with CMAQ to allow the users who are tracking CMAQ issues can find it. Please also review the best practices for describing your issue. [PLEASE READ before posting](https://forum.cmascenter.org/t/please-read-before-posting/1321)