한반도 주변해 GMI 마이크로파 해수면온도 검증과 환경적 요인 = GMI Microwave Sea Surface Temperature Validation and Environmental Factors in the Seas around Korean Peninsula

다국어 초록 (Multilingual Abstract)

Sea surface temperature (SST) is a key variable that can be used to understand ocean–atmosphere phenomenaand predict climate change. Satellite microwave remote sensing enables the measurement of SST despite the presence ofclouds and precipitation in the sensor path. Therefore, considering the high utilization of microwave SST, it is necessaryto continuously verify its accuracy and analyze its error characteristics. In this study, the validation of the microwaveglobal precision measurement (GPM)/GPM microwave imager (GMI) SST around the Northwest Pacific and KoreanPeninsula was conducted using surface drifter temperature data for approximately eight years from March 2014 toDecember 2021. The GMI SST showed a bias of 0.09K and an average root mean square error of 0.97K compared tothe actual SST, which was slightly higher than that observed in previous studies. In addition, the error characteristics ofthe GMI SST were related to environmental factors, such as latitude, distance from the coast, sea wind, and water vaporvolume. Errors tended to increase in areas close to coastal areas within 300 km of land and in high-latitude areas. Inaddition, relatively high errors were found in the range of weak wind speeds (<6 m s−1) during the day and strong windspeeds (>10 m s−1) at night. Atmospheric water vapor contributed to high SST differences in very low ranges of <30 mmand in very high ranges of >60 mm. These errors are consistent with those observed in previous studies, in which GMIdata were less accurate at low SST and were estimated to be due to differences in land and ocean radiation, wind induced changes in sea surface roughness, and absorption of water vapor into the microwave atmosphere. These resultssuggest that the characteristics of the GMI SST differences should be clarified for more extensive use of microwavesatellite SST calculations in the seas around the Korean Peninsula, including a part of the Northwest Pacific.

국문 초록 (Abstract)

해수면온도는 해양-대기의 현상을 이해하고 기후변화를 예측하기 위해 사용되는 중요한 변수이다. 마이크로파영역의 인공위성 원격탐사는 구름과 강수와 같은 기상현상 위성 관측 측기의 경로에 존재하더라도 해수면온도 획득을가능하게 한다. 따라서 마이크로파 해수면온도의 높은 활용도를 고려하면 위성 해수면온도를 정확도를 지속적으로 검증하고 오차 특성을 분석할 필요가 있다. 본 연구에서는 2014년 3월부터 2021년 12월까지 약 8년 동안 Global PrecipitationMeasurement (GPM)/GPM Microwave Imager (GMI) 마이크로파 해수면온도의 정확도를 표층 뜰개 부이 수온 자료를사용하여 검증하였다. GMI 해수면온도는 실측 해수면온도에 비해 0.09 K의 편차와 0.97 K의 평균 제곱근 오차를 보였고, 이는 기존 연구 결과에 비해 다소 높게 나타났다. 이외에도 GMI 해수면 온도의 오차 특성은 위도, 연안과의 거리,해상풍 및 수증기량과 같은 환경적 요인과 관련성이 있다. 오차는 육지에서 300 km 이내의 거리에서 해안 지역에 가까운 지역과 고위도 지역에서 증가하는 경향이 있다. 또한 낮에는 약한 풍속(<6 m s−1), 밤에는 강한 풍속(>10 m s−1) 범위에서 상대적으로 높은 오차가 나타났다. 대기 수증기는 30 mm 미만의 매우 낮은 범위 또는 60 mm보다 큰 매우 높은범위에서 높은 해수면온도 차이에 기여했다. 이러한 오차들은 저수온에서 GMI 자료의 정확도가 떨어지는 기존 연구와일치하며, 연안으로부터의 거리, 풍속, 수증기량에 의한 오차의 경우 육지와 해양의 방사율 차이 및 바람에 의한 해수면 거칠기 변화, 수증기의 마이크로파 대기 흡수에서 기인하는 것으로 추정된다. 이는 한반도 주변해에서 마이크로파위성 계산 SST를 보다 광범위하게 활용하기 위해서는 GMI 해수면온도 오차의 특성에 대한 이해가 필요함을 시사한다.

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