## Search found 36 matches

June 13th, 2019, 9:29 pm
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, Thanks for your reply. I am not clear about the formula for calculating the area. The area is calculated as (111198.323)^2 * lat * lon * cos(lat) The grid area in my simulation is 5000 m * 5000 m, because the grid spacing is 0.05. How is your formula related to the grid spacing (0.05)? ...
June 13th, 2019, 2:47 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, Thank you very much for your reply and help. I ran some simple simulations with ichem=5 yesterday before seeing your rely, and the outputs are consistent with your explanation. But I sampled the deposition value using ‘time average’. As you suggested, ‘Maybe you just want to use a snaps...
June 11th, 2019, 5:26 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, Thank you very much for your help. I am using HYSPLIT to model insect dispersal. The computational particles represent insects. Insects do not loss their mass during wind dispersal process, and will eventually land on the ground. That is why I am only interested in counting the number o...
June 10th, 2019, 10:58 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, Thank you very much for your reply. I am very sorry that I did not make Question 3 clear. For Question 3, I would only like to calculate the number of particles via concentration/density (mass/area) on the deposition layer. As you suggested before, I would be able to work backward to ge...
June 8th, 2019, 2:21 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, Thank you very much for your help. I really appreciate it. Now, I have a much better understanding of how HYSPLIT works. I would just like to confirm some of my final thoughts. Please see the example below and the attached MESSAGE file. Number particle released: 10,000 Emission rate: 33...
June 7th, 2019, 11:19 am
Forum: Dispersion Model
Topic: Sampling Interval Type (snapshot)
Replies: 2
Views: 612

### Re: Sampling Interval Type (snapshot)

Thank you very much for your help, christopher.loughner.
June 7th, 2019, 11:18 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, I actually would like to include dry deposition for my dispersal simulation, and will only sample concentration in a grid cell (m2) on the ground level (0 m). How do I ensure that the mass on the particles is not changing? According to the link that you sent, 'In the special case where ...
June 6th, 2019, 4:19 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Re: Time Step and Concentration Calculation

Dear alicec, Thank you very much for your reply. It is very helpful. I have a much better understanding of concentration calculation now, but I still have two questions. Question 1: Could you please see the example below? Would I be correct? For example, the sampling interval is every 2 hours (120 m...
June 5th, 2019, 9:01 am
Forum: Dispersion Model
Topic: Sampling Interval Type (snapshot)
Replies: 2
Views: 612

### Sampling Interval Type (snapshot)

Dear all, According to the online tutorial, Sampling interval type: Snapshot (or now) will give the instantaneous output at the output interval. What does the output interval mean? Does it mean the last time step within the sampling interval? If so, the instantaneous output refers to a snapshot of w...
June 4th, 2019, 9:30 am
Forum: Dispersion Model
Topic: Time Step and Concentration Calculation
Replies: 35
Views: 3465

### Time Step and Concentration Calculation

Dear all, I would like to clarify something on dispersal modelling. I am aware that time steps vary a lot during simulation. Some time steps are 6 minutes while others can be 12 minutes. The minimum time step is 1 minute. Question1: Does HYSPLIT calculate concentration for a grid cell based on each ...