Storm is the primary software to visualize and process data from first generation Aquadopp and AWAC instruments. Both current and wave data can be visualized and processed.
The software can be downloaded from the Nortek software and firmware download page, and installation requires a valid license. If you are interested in purchasing the software, please contact your local Nortek sales representative.
Storm can be used with data files from the following Nortek instruments: Aquadopp and AWAC
This article provides tips, tricks, and answers to frequently asked questions to help you make the most of the Storm software.
How does Storm calculate the Signal to Noise ratio (SNR)?
To calculate SNR one needs the return signal strength and the instrument noise. There is no 'noise ping' in the instruments that can be used with Storm. What Storm does is to assume a noise floor as given below.
- Aquadopp 25 counts
- Aquadopp Profiler 400kHz 33 counts
- Aquadopp Profiler 600kHz 33 counts
- Aquadopp Profiler 1MHz 25 counts
- Aquadopp Profiler 2MHz 18 counts
- AWAC 600kHz 33 counts
- AWAC 1MHz 20 counts
To get a rule of thumb cut-off at 3dB you need to find the noise floor of your instrument and compensate for this if it deviates from the hard-coded values too much.
We realize this is a bit cumbersome, but SNR is not giving the full picture either. Needed SNR to obtain good current measurements have decreased during the refining of these instruments through the years. Different conditions may require different SNR to give good readings.
A good check of the validity of the data is to check that the vertical velocity is close to zero. Current profiles that show large current variations vertically or vertical structures should be flagged suspicious. The ones that are most doubtful are those that are physically unrealistic (e.g. 1 m/s changes over a few meters). The measurements in a profile that are far from the mean are best removed.
Example of SNR compensating in Storm
Your Aquadopp Profiler has a noise floor of 25 counts. Storm assumes 18 counts as noise floor. You will then need to add (25-18) counts*0.43dB/counts=3 dB. If you like to use the 3dB rule of thumb threshold, you actually need to input 6dB
The noise floor of your instrument can be found in different ways
- It is stated in the final test check list that came with the instrument.
- The amplitude profile will converge to the noise floor.
- A bench test with the instrument out of water would also give the noise floor.
- Contact Nortek
The db/count relation may also vary a bit between instruments, but 0.43 is an OK estimate.
How do I exclude one beam from processing?
When processing the data you have collected, you may encounter a scenario where a particular beam is no longer operational or has become obstructed due to a physical obstacle. In order to optimize the data processing, it may be necessary to exclude such a beam from further analysis.
One caveat to excluding a beam, such that only two beams are used, is that the three dimensional flow is now under-determined, or does not have enough information for a unique solution. Therefore the processing requires an assumption and that is the vertical velocity is set to zero and all flow is horizontal. This is not ideal but probably not far from the truth, and the only way to arrive at a unique solution with just two functional beams.
1. Locate the "Processing" tab after opening your desired project.
2. Choose to open "Settings...".
3. Ensure that you are in the tab "Current Data Quality Control", and navigate to the "Beam rejection" section. Here, you are able to exclude one beam.
Updated