From the above slides we can point out some distinct types:
HMS100
- Search and Rescue, Maritime Patrol
- Environmental research and crew familiarization.
From the above, I deem it to be a part training aircraft for the crew.
HMS200
- Search and Rescue, Maritime Patrol
HMS400
- Search and Rescue, Maritime Patrol, Sea Surface Surveillance
- equipped with ESM and CMDS devices
HMS500
- Search and Rescue, Maritime Patrol, Sea Surface Sureveillance, Sub-Surface Surveillance, Pollution Control
- equipped with MAD, MWR and sonar-buoy dispensers.
The above seems to render it a possible replacement for Iran's aging PC-3 Orions. The inclusion of a Microwave Radiometer (MWR) device is rather interesting. MWR mounts enable time-slotted measurements of water vapor and liquid water in the atmosphere using a microwave receiver. I am uncertain of the military use of these though. The measurements that can be obtained range from cloud liquid water, precipitable water and so forth. This is probably intended for the pollution control feature.