１．Introduction

　　This consortium was established with the aim of contributing to society through the use of solar radiation data based on satellite observation data. We will explore the possibility of new science and technology by providing the research results of radiation handling technology cultivated in the field of climate research to a wide range of fields and enhancing mutual cooperation with other fields. In addition, we will cooperate with companies in various fields and develop activities to make high technology widely useful to society. The amount of solar radiation is one of the basic physical quantities in weather and climate, and since the amount of solar radiation based on satellite observations has information on its surface distribution, it is being considered for use in energy and agriculture. At present, Japan is undergoing major changes with the Great East Japan Earthquake as a turning point, and the construction of a more diverse and robust social infrastructure is required. In particular, there is a high level of interest in renewable energy in relation to the energy problems that have become apparent due to the earthquake disaster, and the use of solar energy that falls on the earth, such as solar power generation and solar heat utilization, is an important period in which technological development is progressing rapidly. In addition, since surface-area solar radiation data can be used as basic data for grasping the growing state of agricultural crops and predicting yields, contributing to food security, including agricultural use, is also one of our goals. Right now, collaboration in various fields is needed, and we must remove barriers between fields and work closely together to achieve results. Therefore, this consortium will lay the foundation for the use of solar radiation by widely providing solar radiation data that can be applied to other fields such as renewable energy (solar power generation, solar thermal utilization), agricultural use, food security, etc. In addition, we will actively promote industry-academia-government collaboration, promote research and business development that incorporates the latest technology, and contribute to the revitalization of society. Furthermore, as a contribution to the world, we will explore the ideal form of science and technology to enrich humankind by expanding this activity worldwide.

Keywords IPCC-SRREN, PV2030+, photovoltaic power generation, solar thermal utilization, food security, crop yield, biomass

２．Background, Philosophy, and Purpose of Establishment

　　Solar radiation is the only source of energy that drives the weather and climate on the Earth's surface. While the earth receives solar radiation and warms up, it emits energy into space by terrestrial radiation (infrared radiation) associated with the temperature. These heating and cooling processes keep the earth in a viable environment for life. Although it is the atmosphere that maintains the environment of the earth's surface in its present state, the effect that the atmosphere is believed to have on the earth's energy budget has not yet been quantitatively elucidated. In particular, clouds have both the effect of cooling the earth by reflecting solar radiation and the effect of keeping the earth warm by absorbing and re-radiating the earth's radiation. However, since the generation and development of clouds are related to other factors such as evapotranspiration and precipitation, including the water cycle of the earth's atmosphere, it is difficult to quantitatively evaluate the effect of clouds on climate, and it is positioned as an important issue in climate research. Various techniques have been used to estimate the amount of downward solar radiation on the earth's surface, that is, the amount of solar radiation.

1. 1. Regression analysis model based on actual observed values . A method of calculating the amount of insolation by linking the amount of insolation observed by a pyranometer installed on the ground and the parameters of the meteorological field, and expressing the transmittance of the atmosphere statistically. It has the advantage of high-speed operation due to the small amount of calculation, but there is a limit to the corresponding conditions because it does not have a clear physical model, and because it depends on observed values, it is necessary to constantly collect statistics for changes as regression analysis. Also, it is difficult to apply to places with different trends from statistics.
   
2. 2.An energy flow model describing the distribution of solar energy. The amount of solar radiation is calculated using a simple formula that describes the energy flow in 1 or 0 dimensions from the time the energy falling from the sun is attenuated by each element of the atmosphere until it reaches the ground. Since only the energy flow is handled, the wavelength characteristics of each atmospheric element cannot be considered.


3. 3. A radiative transfer model considering the wavelength characteristics of atmospheric elements. Solar radiation reaching the top of the earth's atmosphere from the sun is absorbed and scattered by absorbing gases such as water vapor and ozone, and fine particles in the atmosphere such as cloud particles, before reaching the earth's surface. This is calculated for each wavelength and each atmospheric layer based on the radiative transfer theory of electromagnetic waves. Although the exact solution of radiation dose can be obtained, it requires a very long computation time compared to other methods.

　This consortium promotes the use of solar radiation analysis results based on the radiative transfer model solution, a technique cultivated over many years by the radiative community in climate research. The optical properties of cloud particles, which are the largest uncertainties for solar radiation, are obtained by inverse analysis from geostationary satellite observation data. Also, the problem of calculation time due to radiative transfer calculation was solved by developing a solver that operates at high speed. As a result, it is possible to perform analysis according to the observation frequency of geostationary satellites, and to provide solar radiation data in quasi-real time.

Application to renewable energy
　　Photovoltaic power generation is a power generation method that converts the solar radiation that falls on the earth into electricity. It emits no greenhouse gases during power generation, and likewise produces no waste, wastewater or exhaust from cooling, or noise or vibration from operation. Therefore, since it can be installed directly at power demand points such as buildings, it can be distributed as a small-scale power source, including urban areas and ordinary houses. Solar thermal utilization is an energy utilization method in which thermal energy from solar radiation is used for hot water supply, air conditioning, or power generation through a heat medium. Generally speaking, it is easy to convert energy into heat, so the use of solar heat is characterized by high efficiency. Strictly speaking, there are multiple definitions of renewable energy, but as renewable energy defined by the IPCC, solar power generation and solar heat utilization are expected as one of the measures to mitigate climate change. In 2008, the cumulative installed capacity of solar power generation in Japan was 2. Although it is about 17 GW, it is estimated that about 173 GW will need to be introduced in 2050 as a long-term countermeasure against global warming. Especially during the summer, when power demand peaks during the daytime, it is believed that this will have an effect on power supply during peak hours. In addition, unlike thermal and hydroelectric power generation facilities, it does not require long-term construction work for installation and can be easily miniaturized. Therefore, immediately after the Great East Japan Earthquake, it played a role as an emergency power source for charging flashlights and mobile communication devices at night in some areas. At present, energy control approaches such as HEMS and BEMS are also increasing. Since the Great East Japan Earthquake, the introduction of photovoltaic power generation and solar heat utilization has accelerated due to the concept of the best mix of electricity, and various technological developments are currently underway. This consortium will provide solar radiation data that contributes to the development, introduction and operation of new technologies for solar power generation and solar heat utilization in renewable energy. Various approaches have been attempted to develop solar radiation prediction technology, but there is no definitive solar radiation data with surface information to evaluate its accuracy. Therefore, solar radiation based on satellite observations may be useful in evaluating and improving prediction accuracy. In addition, with the spread of photovoltaic power generation and solar heat utilization, it is conceivable to use the current value of solar radiation in a wide area for the construction and operation of control theory using HEMS, BEMS, and microgrids. Solar radiation based on satellite observations can be useful for evaluating and improving prediction accuracy. In addition, with the spread of photovoltaic power generation and solar heat utilization, it is conceivable to use the current value of solar radiation in a wide area for the construction and operation of control theory using HEMS, BEMS, and microgrids. Solar radiation based on satellite observations can be useful for evaluating and improving prediction accuracy. In addition, with the spread of photovoltaic power generation and solar heat utilization, it is conceivable to use the current value of solar radiation in a wide area for the construction and operation of control theory using HEMS, BEMS, and microgrids.

Agricultural use and application to food security
　Solar radiation and an appropriate amount of precipitation are essential growth factors for crops. Lack of sunlight has a significant impact on the growth of crops, but too much sunlight promotes evapotranspiration and deprives the soil of moisture. In addition, since crops have diverse ecology depending on the type, the optimal amount of sunlight and soil moisture varies. Precision agriculture, which has shown remarkable progress in recent years, is an advanced agricultural management technology that helps improve the yield and quality of agricultural products and reduce the environmental load by better understanding the conditions of agricultural land and crops. In the application of remote sensing, satellite and aircraft observation data are utilized for grasping the state of crops in each field and environmental management in the field. On the other hand, empirical methods using weather conditions as parameters have long been tried to predict crop yields, but in recent years, yield estimation methods using crop growth models have also been developed. Changes due to weather conditions such as reduced sunshine hours, cool summers, and droughts affect the yield of agricultural products and destabilize the food supply. Especially in Japan, which relies on imports for most of its food, a stable supply of food through imports is required due to various factors inside and outside the country. In addition, hunger and malnutrition are recognized as food security issues worldwide, and since 1995, East Asia has been transformed into a grain importing region, and it is believed that the world's grain inventories are on a declining trend. This consortium will provide solar radiation data that can be used as agricultural supplementary data in precision agriculture, etc., and to grasp the yield situation in a wide area in food security, that is, to contribute to both macro and micro. The amount of solar radiation provided in quasi-real time can be used as a history of the amount of solar radiation in a wide area to predict the yield of agricultural crops and grasp the food yield in estimating biomass in a wide area.

Among social infrastructures, transportation and logistics are the ones that make the most active use of weather information. For example, railroads, aircraft, and ships refer to weather forecasts to formulate operation plans, and refer to the current conditions for the day to modify and operate the operation plans. As a result, we are able to avoid risks such as large-scale accidents and realize stable operation. Accidents caused by natural disasters in modern railways, aircraft, and ships seem to be kept very low, but this can be said to be a high standard for social infrastructure. Since energy infrastructure such as electric power requires high stability, it is necessary to quickly establish operation technology as a social infrastructure that can be operated stably using various information even as the introduction of renewable energy progresses. In particular, it is considered that solar radiation with surface information based on satellite observations is effective. The amount of solar radiation is a basic parameter in weather and climate, and since it is closely related to our lives, it can be applied to various fields, including medical care and industry. The purpose of this consortium is to promote new research and business by removing barriers between fields, and to contribute to society by revitalizing society. We also aim to contribute to the world by expanding these activities worldwide.

３．Specific activity

　This consortium will widely disclose solar radiation data based on satellite observation data, mainly solar radiation, and carry out activities to make it useful in various fields. To that end, we will implement data distribution efforts and support related to promotion of use. The consortium will manage the quasi-real-time data delivery server and archiver for distributing the data, which can be used as preliminary reports of the amount of solar radiation analyzed in quasi-real time, or in which accumulated data and past data are used as history. We will also collect opinions on better usage and newer data products and provide feedback to users and developers.