Questions about sensinput file

Hi, I’m new to CAMQ-HDDM. Although I’ve already run it succesfully, I had some questions. Looking forward to your reply, thanks!

  1. EMIS term. I have some problems using “EMIS_1”,and fixed it with replacing EMIS_1 with TOTA. But i don’t know how to use more than 1 emision file, something like “EMIS_2”?
  2. AMOUNT term. If i want to cut 20% NOx in the region_1 using positive number, the next line after AMOUNT should be 20, 0.2, 80 or 0.8?
  3. Layer term. For now, CMAQ-5.2-DDM only support 1 layer, will it be the plan for the next version.

Looking forward to your reply, many thanks!

Although the above questions remains unsolved, i have new understanding about it, but i don’t know whether it’s right or wrong.

  1. EMIS: Suppose i have 2 gridded emssion files A and B. I have to add B to A and make a new gridded file C to run CMAQv5.2 if i turn off HDDM. If i hope to get the sensitvity of B, is it true that setting EMIS_1=A and put B in the seninput file. And I am confused about the result file. Does it mean the difference between the result of C and A?
  2. Amount: Looking forward to someone’s response. It means emission rate or the ratio of emission. Many thanks to you.

Hi Franky,

Its very important to note that my answer to your question is dependent on using DDM in CMAQv5.2. The interface will be substantially changed in the upcoming release, because CMAQ emissions treatment significantly changed and the following approaches will not work!

For the EMIS term, using the keyword “TOTA” will use all of the emissions. You can specify a subset through using environment variables of the emissions streams. EMIS_1 is probably not the correct environment variable names. I don’t remember the release scripts exactly, but you it should be something like “GRIDDED_EMIS” for the gridded file and something like “PT_EGU” for the point source EGUs (for example). You also need to specify the type of file you are using (this may the problem you ran into).

Here is an example of a sensitivity definition I ran a while ago (again, this will not work in 5.3+):


This example uses 1 (one) gridded file labeled “USANTHRO” and 5 (five) pairs of stack group/stack emissions files. Species NO2 and NO are pulled out of each of these 6 emissions inputs for sensitivity.

The “AMOUNT” can not be used to cut emissions by percentages. It is an actual emissions rate amount. This option is basically never used and there will be much easier ways to accomplish this functionality in the next release, so its probably going away anyways.

The “LAYER” term is also similarly never used, so it will not be upgraded. There will be easier ways to handle these things through the new CMAQ emissions streams upgrade.

I don’t exactly understand what you are trying to accomplish with your first question in the second set. You can, however, calculate sensitivities to emissions not used in the base CMAQ simulations. So, you can specify CMAQ to use FILE_C to calculate concentrations as it normally does. At the same time, you can calculate sensitivity to species in FILE_B. You just need to make sure you define everything in your runscript.

For some reason, the forum collapsed the spaces out of my sensinput.dat example. You still need to preserve the correct formatting…

Hi, Sergey,

Thanks so much for your prompt reply.

For the EMIS term, the corrct environment variables is EGRIDFILE1-n.

I am doing some work about the senstivity of cutting emissions by different percentages. As the set 2 said in the first question, i want to know the effect of cutting 20% NOx of Emission File_B in different regions.

Another question, i am confused about the result of HDDM and ISAM. Does the result of ISAM mean the difference of pulling out the emission like HDDM? In my knowledge, ISAM should include the effcect of reactions on local species(primary & secondary) and species (primary & secondary) from other regions.

Thanks so much and best regards


To calculate the impact of a 20% cut of NOx from Emission File_B in a region, calculate the sensitivity to NOx from that region and multiply the resulting field by 0.20.

For the difference question… ISAM calculates source apportionment. DDM calculates sensitivity. I am not exactly sure what you are asking, but it may be helpful to review some of the literature on this to get a better understanding. There are papers from our group and also from the CAMx group and some some of the European models as well.

Hi, Sergey,
Since the sensitivity analysis cannot be used for studying the sources of secondary pollutants, the source receptor relationships for secondary pollutants should be taken into consideration. To be specific, the result of ISAM should caculate the contribution of every reaction.

I will search for more literature about ISAM. Thank you for taking the time.
Best regrads


To clarify, sensitivity certainly can be used to study the sources of secondary pollutants. And ISAM does calculate contributions from every reaction relevant to the thing you are tracking.


Thanks for your reply. I’ll check it later.

Hello Professor @Sergey, and @franky

I am still a beginner in using CMAQ-DDM-3D, fortunately I have run successfully the CMAQ_v52_DDM-3D (with the resulting ASENS*, SENGRID*, SENWDEP* and SENDDEP* outputs). I need help on the POST PROCESSSING of these sensitivity outputs; which tools should I use?

I have been able to use combine and VERDI to analyse the ACONC* output successfully.


CMAQ-DDM-3D outputs are in the same file format as your ACONC* files and will open with VERDI and other tools and post processing software you use for standard CMAQ.


Hello @sergey,

The user guide describes clearly the use of IREGIONS term and the relevant associated specifications as well as the correct setting in the SEN_INPUT control file. But what i am struggling with is how to create such (netcdf) file. Kindly, shed some light on how to prepare this REGIONS file… and (or) is it okay to use the ISAM regions file?


The DDM regions files and the ISAM regions files use identical formatting and are interchangeable.


Thanks @sergey… this is very useful information

Hi Sergey, I am running DDM with CMAQv5.3.2. Is there anything needed to change about this version. I had set DDM3D_ES to Y and set the environment variable for EGRIDFILE1 to point to the emissions file in run_cctm.csh script. But an error about “User specified DDM Emissions Stream - EGEIRFILE1 - not found in available emissions streams” occurred.

Hi, Sergey,
Could you help me if i want to calculate the sensitivity of PM2.5 to its precursor emissions, how should I set the species in sensinput.cmas.dat?
I set the emissions species related to PM2.5 but an error is showed “parameter not found in species name array”.
Thank you for taking the time.

You need to use the CMAQ CGRID species for PM sensitivities and not the emissions surrogates.

Also, DDM for PM species is not yet implemented in the latest CMAQ release.


Thank you for your reply.

Hello Professor @sergey ,
Sorry for bothering you, your answer to this question confuses me. I thought that while CMAQ 5.2 version dose not supports second-order sensitivity calculation for PM species, it does support first-order sensitivity calculation. Am I right?
Looking forward to your reply, thanks!

Hi Sergey,
I would like to make sure DDM does not work in CMAQ v5.3+ because I noticed that the compilation option of ‘set DDM3D_CCTM’ is available in bldit_cctm.csh and can be built CCTM_v533_DDM3D.exe successfully. However, I should go back to CMAQ-5.2_DDM-3D if I need to use HDDM, am I right?