Development of a lower system noise temperature receiver for future 300GHz band spaceborne radiometers

Satellite observations with 300-GHz band radiometers are expected to bring advantages to atmospheric remote sensing, such as sounding of water vapor profiles and estimating thin cloud properties. However, it had been difficult to satisfy the accuracy and precision requirements of the observation, owing to high noise levels of 300-GHz band receivers. The system noise temperature of receivers is proportional to a radiometer's brightness temperature resolution. It is a reason why the lower noise level receiver is desired to a radiometer. We have experimentally confirmed that the receiver using a 300-GHz LNA achieved about one fifth of system noise level compared to that of without LNA. It implies that we can develop a 300-GHz band spaceborn radiometer with 1 GHz bandwidth, 100msec integration time and about 1K of brightness temperature resolution. Our final goal is to contribute to improving the accuracy of the vertical profile water vapor and the amount of ice clouds by satellite observations with our 300 GHz-band radiometer.