Presenting Setinel 6A, focusing specifically on Poseidon-4 radar Altimeter

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# Presenting Sentinel 6A with specific focus on Poseidon-4 radar Altimeter

### Week 2

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# How will we present Poseidon and what aims of this presention are!

- Orbital and Technical Specifications

- Stake Holders and parties involved

- Understanding what Poseidon does and who it benefits

- Visualising how the Sensor works
]

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# What exactly is Sentinel 6A?

.pull-left[.milieu[.center[ <img src="images/Sentinel-6-general.jpeg" alt="drawing" width= "400"/> .small[
[Source and additional information: ESA Sentinel website](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-6)]
]]]
.center[ .low[ The completion of this project is the **illustration of the success of international collaboration in International Spatial Research!**]]

.pull-right[
**Key Facts**
- Sentinel 6 part of the Coperinus Programme with the aim of providing in-depth data regarding sea-surface height measurements

- Main control is lead by [EUMETSAT](https://www.eumetsat.int/) which is Europe's principal weather and climate satellite organisation

- Full name of platform: Sentinel-6A Michael Freilich - named after American Oceanographer [Michael Freilich](https://en.wikipedia.org/wiki/Michael_Freilich_(oceanographer)) which was an important player in facilitating collaboration between international institutions

- NASA, EUMESTAT, ESA, European commission, CNES (french spatial research center) all played an important role in the success of the project
]

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# Technical details on Sentinel 6-A and it's Orbit

.pull-right[.milieu2[.center[
<img src="Sentinel_6A_Orbit.gif" alt="drawing" width= "100"/>
.small[[Animated GIF of the Sentinel 6A orbit, provided by ESA](https://climate.nasa.gov/climate_resources/238/animated-gif-sentinel-6-michael-freilich/)
]]]]

- Twin mission: with 6A and 6B

- 6A launched on 21st November 2020
  
- 6B to be launched in 2025
  
- 5.5 year mission duration estimation

- Entered Service 21 June 2021

- Launched By SpaceX

- Launched in California USA

- Total Cost to Launch estimated to be approximately [100 million](https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-sentinel-6a-mission)

]

- Geocentric Orbit (orbits around Earth)

- Orbit Altitude: 1336 km

- Revisit Time: 10 Days

- Mass: 1192 kg at time of launch

- Inclination: 66.0°

- 6 different instruments available

- Dimensions: 5.13 x 4.17 x 2.34 m

]
]
]

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# A break-down of instruments on available on the platform

## AMR-C
## GNSS RO
## REM
## POSEIDON-4 ALTIMETER
## Precise Orbit Determination Payload (POD) consisting of:
### DORIS, LRA, GNSS POD

---
.center[
<img src="images/sentinel-6-instruments-detailed.png" width="70%" />
].small.center[Source: [ESA](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-6/instrument-payload)]

- Stands for Advanced Microwave Radiometer - Climate Quality

- 3 spectral bands: 18.7, 23.8 and 34 GHz. With additional experimental high-frequency channels (90, 130, 168 GHz) [(Source)](https://www.earthdata.nasa.gov/sensors/amr-c)

- Accounts for the amount of water vapor in the atmosphere

]
.panel[
.panel-name[GNSS RO]

- Global Navigation Satellite System Radio Occultation

- Instrument providing atmospheric vertical profile information

- Used as a weather forecasting tool and ultimately used as a weather forecasting tool

]
.panel[
.panel-name[DORIS]

- Doppler Orbitography and Radio-positioning Integrated by Satellite

- Uses two different stable radio frequencies to precisely determine its line-of-sight velocity [(Source)](https://www.jpl.nasa.gov/news/press_kits/sentinel-6/mission/spacecraft/#:~:text=Each%20ground%20station%20acts%20as,line-of-sight%20velocity.)

]

- Radiation Environment Monitor

- Used for the measurement of energy fluxes and understanding radiation of the real-time location of the satellite

]
.panel[
.panel-name[LRA]

- Laser Reflector Array or Laser Retroreflector

- Well established tooled used in previous missions such as Jason-3

- Principally used to precisely determine (at cm level resolution) the orbit of the satellite using short light wavelength

]

- Global Navigation Satellite System Precise Orbit Determination

- Provides information on orbit trajectory

- Primordial for the satellite to maintain correct orbit throughout mission
]
]

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# How exactly does Poseidon 4 work and why is it useful?

Here we illustrate how the Poseidon 4 Dual-Band Radar Altimeter works, showing how both low and high synthetic resolution are collected, recpectively on the left and right below

<img src="sentinel 6.gif" width="100%" />
.small[ Gif Showing the High and Low Frequencies used by Poseidon 4, cropped from ESA original video available [here](https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-6/How_it_works)]

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# Poseidon 4 use and technical details!
<br/>

- Acquires two types of data simultaneously:

- SAR processing which provides at very **high granularity** but requires a tremendous amount of processing power
  
  - Conventional Lower resolution approaches that allow for faster sharing of data with **less processing power** necessary
  
- Has the major benefit of allowing for **cross-platform comparison and continuity** of measures

- Methods coincide with Jason and Topex allowing for data to be collected without a break
  
- Azimuthal Beams (straight up above, nadir pointing) with a resolution of **20km** Instantaneous Field of View (IFOV) and **300m** in SAR

- Main expectations from this sensor is to provide high accuracy and precision altimetry for Sea Surface Height, Wave Height and wind speed.

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# The Main goal of Sentinel 6A is to provide reliable and granular data for better understanding of the effects of Climate Change on Earth's Oceans by analysing sea surface topography

# Poseidon 4 Radar Altimeter provides a key role in supporting ocean forecasting systems, cliamte monitoring and environmental montoring

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# THANK YOU!!