The mission of the existing GOCI (2010~2021 operation) is inherited as it is.
It is intended to monitor the general marine environment in the Northeast Asian waters around the Korean Peninsula.
In addition, it is possible to additionally observe the full disk area, which was not available in the existing GOCI.

While the main purpose was to monitor/observe the sea area around the Korean Peninsula,
No. 2 added a function to observe the Indian Ocean-South Pacific Ocean-Pacific in addition to the function of No.
In order to improve the performance of the satellite, 
the number of bands used was increased from 8 to 12, 
and the spatial resolution was also increased by about 4 times from 500m to 300m.

Existing overseas satellites were polar orbit satellites capable of photographing a given sea area about once a day, 
but GOCI-1 and 2 are geostationary orbit satellites that take 8 and 10 images of the sea area around the Korean peninsula every hour.
Global full disk shooting is taken once a day. 
GOCI and GOCI-II are the only marine satellites that monitor the marine environment in geostationary orbits so far.

Except for the GOCI series, all marine satellites are polar orbital satellites that can shoot one sea area less than once a day.
However, the GOCI series stays in a geostationary orbit and can be filmed 8 to 10 times a day in the same place per hour.
In other words, the time resolution is incomparably high, 
and based on this, the observation of the marine environment that changes during one day was made possible for the first time in the world.
In addition, GOCI-2 satellites are located at a high altitude of 35,000 km, 
called geostationary orbit, but can observe relatively low polar orbits (about 7-800 km) with a similar or superior resolution to marine satellites. 
The downside is that it stays in geostationary orbit, 
so unlike a polar orbit satellite that photographs the entire earth once a day, only half of the earth (full disk) can be photographed.

When the verification that the development of a satellite is necessary for marine research by a domestic user group (Korea Ocean Research Institute, etc.) 
is made, the mission is determined and the optical specifications of the satellite required to perform the mission are determined.
When it is determined that there is no problem with the current technical possibility and cost in developing a satellite 
with the specifications required by the Daum Aerospace Research Institute and the user, a budget application is made to the government.
The Institute for Aeronautical and Space Sciences has created a satellite development plan and independently developed it without the request of a user group.
However, in recent years, user-centered development has been carried out by introducing the development process of advanced countries.
In simple terms, a house is built, similar to the way the owner of the house makes the necessary basic design and design, and then entrusts it to a builder.
In the past, the Ministry of Science and Technology organized its own budget to develop satellites and service the data to marine users.
However, at the moment, the demand department and the Ministry of Oceans and Fisheries secured a budget at the request of the Korea Ocean Research Institute 
and the Aerospace Research Institute, and requested the development from the Aerospace Research Institute.
However, the method of overseas advanced countries is that the development proposal organization (i.e., Korea Ocean Research Institute), 
which is the representative of the user group of the satellite, secures the national R&D budget through the Ministry of Oceans and Fisheries, 
and then promotes the consignment development to the Aerospace Research Institute. have.

The technology of aerospace researcher cannot be independently developed 100%. Therefore, it is necessary to seek help from developed countries abroad.
GOCI-1 & 2 satellites were developed in cooperation with AIRBUS (formerly Astrium) in France. 
During the development period, when a technical difficulty or a situation that causes a surge in development cost is encountered, 
three organizations of the Aerospace Research Institute (KARI)-the Hinguk Institute of Ocean Science and Technology (KIOST)-AIRBUS 
will negotiate and coordinate it.

Just because only satellites were developed, satellite data cannot be used immediately.
Optical data for each band observed by satellites go through a process called primitive digital data (Level 0), 
optical data (Level 1), and finally, marine environment analysis data (Level 2).
From L0 to L1, AIRBUS (formerly Astrium) and the Aerospace Research Institute, 
and L1 to L2 will be in charge of the Korea Institute of Ocean Science and Technology. 
In the case of GOCI, the Ocean Satellite Center developed a software called GDPS and distributed it to users.
In the case of GOCI-II, the data will be processed by the ground station system (G2GS) developed by the GOCI-II 
Institute of Ocean Science and Technology.

The first image data from the Cheonrian satellite are primitive and are full of information that cannot be properly recognized except by experts.
Various analysis processes are required to convert this into an image suitable for observation purposes.
First of all, the radiation correction that changes the image taken with digital values ??into the correct brightness value, 
the geometric correction that adjusts the position of the image to the position above the exact latitude and longitude of the earth, 
and the correct sea color by removing the influence of the atmosphere 
that filled the sea and satellite It is divided into an atmospheric correction process that finds out.
Finally, marine environment information is provided to users through a marine environment analysis process 
that analyzes the ocean color information estimated through atmospheric correction and converts it into a marine environment variable value.

The operation of GOCI is largely divided into satellite data analysis, quality control, technical research, and data distribution.
The Korea Advanced Institute of Ocean Science and Technology analyzes and processes the satellite data received in real time 
and transmits it to the National Oceanographic Satellite Center of the National Oceanographic Research Institute, 
and the National Oceanographic Satellite Center provides services to the public based on this data.
For the analysis of satellite data, objective quality control and technical research for quality improvement must be accompanied. 
The Marine Satellite Center of the Korea Institute of Maritime Science and Technology 
has been in charge of successful GOCI operation over the past 10 years, securing core technologies related to this. 
It has been recognized worldwide. In the case of the National Maritime Satellite Center, 
it was established by the National Oceanographic Research Institute in 2019, 
and has taken over the mission of data distribution service that the Maritime Satellite Center has been dedicated to, 
and is carrying out this successfully.

The main role of the Aerospace Research Institute is the control function of the satellite. 
GOCI-II is on the same satellite as the Ministry of Environment's Atmospheric Environment Satellite (GEMS) (Cheonlian Satellite 2B). 
KARI is in charge of shooting, orbiting, and transmitting data to the ground for the 2B of the Cheonlian Satellite.

The user group will be used by various marine/land-related users such as the Korea Institute of Ocean Science and Technology, 
the nationwide marine-related universities, the Meteorological Administration, the Environmental Research Institute, 
the Municipal Fisheries Research Institute, and the National Territorial Research Institute.

The data provided by KOSC are L0, L1, and L2 data. The L2 data is again divided into a total of 26 types.
It is estimated that more academic research field users will use Level 0 or L1 data, and if they are not experts, they will receive L2 data.
The Ocean Satellite Center plans to develop and distribute XXXX, a data analysis software for users of L0 or L1 data.

Satellite data analysis software that can be processed on personal PCs is being distributed on the homepage of the Ocean Satellite Center.
This S/W was produced based on SNAP (Sentinel Application Platform), which is ESA's satellite data analysis open S/W.

In principle, it is a free service. 
In some cases, if you want a large amount of data service, you can receive actual costs for storage media and delivery.

GOCI & GOCI-II satellite data are observed at a great distance from the earth, 
so when an optical signal from the sea level arrives at the satellite, 
the optical signal from the atmosphere enters more than 10 times that of the sea signal.
In addition, when the data that has been corrected for this waiting signal is analyzed again, 
an additional error occurs.
The calibration performed by the Ocean Satellite Center is continuously being carried out with the aim of minimizing errors 
that occur during this process.
In order to do this, field observation must be performed first, 
and the algorithm must be improved through endless feedback through comparison of observed data and satellite data.
Gum calibration cannot be performed only with data collected for a short period of time, and for this reason, 
marine satellite experts around the world continue to perform gum calibration for a long period of time 
from the start of the satellite mission to the time of closing.

In order to improve the quality of data, it is common to conduct comparisons between data measured directly in the field and satellite data. 
However, since field observation on the sea requires a lot of experience and understanding of the optical environment, 
in most cases, without expert knowledge, only low-quality data that cannot be used for calibration, 
no matter how expensive equipment is used, is in most cases.
Therefore, the collection of field data is carried out by the optical experts of the Marine Satellite Center of the Institute of Ocean Science and Technology, 
who have accumulated know-how in the field for decades.
Even the data collected through this meticulous process can be used as data that can be used for gum correction once again 
through the process of correcting it to more accurate data based on the theory of radiation transfer.
If the continuously collected field data and satellite data are compared regularly, 
objective satellite data quality verification is possible, and the accuracy of the satellite data is improved again based on this result.
In order to improve the accuracy of satellite data, 
an understanding of atmospheric correction and proxy correction as well as radiation transmission theory is required. 
Currently, the marine satellite center has the best know-how in the field through its long-accumulated experience.

If calibration is performed only around the Korean peninsula, the accuracy of the data can only be guaranteed in the waters around the Korean peninsula.
In other words, in the case of GOCI-II, since the full disk area is observed, the help of foreign users/researchers is absolutely necessary for calibration.
To this end, the Maritime Satellite Center has been sharing data and technologies through scientific exchanges 
or MOUs with overseas marine researchers for a long time.