<p>You have got your emissions over a square kilometer. To get to square meters you divide by 1000000 since <span class="math-container">$1km^2=10^6m^2$</span>.</p>

CC BY-SA 4.0
2019-11-14T14:34:17.333Z
2019-11-14T14:34:17.333Z
Christoph
<p>I have a grid shapefile that has a resolution of 1km x 1km. </p>

<p>This grid is then used to spatially allocate road emissions. </p>

<p>My goal is to get the emissions in the unit: <strong>μg m-2 s-1(microgram per square meter per second)</strong> since this is the emission unit for aerosols in the WRF/Chem</p>

<p>I manage to get the emissions for a certain grid cell by multiplying the total emissions in (micrograms/s) to the ratio of the road length present inside the grid cell to the total road length<a href="https://i.sstatic.net/9snhv.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/9snhv.png" alt="enter image description here"></a></p>

<p>Now I have the emission for that grid cell in <strong>μg s-1</strong> (micrograms/second).</p>

<p>My question may be silly or simple, but I am thinking if I still need to divide my emissions by 1000 (since 1km = 1000m) to get the final emission unit I need </p>

<p>(Final unit needed:  <strong>μg m-2 s-1(microgram per square meter per second)</strong>)</p>

<p>Am I right? Hoping someone could help me with this. Thanks!</p>

<wrf><wrf-chem><emissions>
Spatial allocation of road emissions and unit conversion
meteo_96
# Spatial allocation of road emissions and unit conversion

(Asked by: username_0 on 2019-11-14)

I have a grid shapefile that has a resolution of 1km x 1km.

This grid is then used to spatially allocate road emissions.

My goal is to get the emissions in the unit: **μg m-2 s-1(microgram per square meter per second)** since this is the emission unit for aerosols in the WRF/Chem

I manage to get the emissions for a certain grid cell by multiplying the total emissions in (micrograms/s) to the ratio of the road length present inside the grid cell to the total road length[![enter image description here](https://i.sstatic.net/9snhv.png)](https://i.sstatic.net/9snhv.png)

Now I have the emission for that grid cell in **μg s-1** (micrograms/second).

My question may be silly or simple, but I am thinking if I still need to divide my emissions by 1000 (since 1km = 1000m) to get the final emission unit I need

(Final unit needed: **μg m-2 s-1(microgram per square meter per second)**)

Am I right? Hoping someone could help me with this. Thanks!

**Tags:** wrf, wrf-chem, emissions


---

## 1 answers

### Answer by username_1 on 2019-11-14. Score: 2 | Accepted answer

You have got your emissions over a square kilometer. To get to square meters you divide by 1000000 since $1km^2=10^6m^2$.


---

