HY-2B扫描微波辐射计海温产品在典型区域的精度验证和分析

“海洋二号B”卫星(HY-2B)于2018年10月25日发射,是我国第二颗海洋动力环境探测卫星,其上搭载有包括扫描微波辐射计(SMR)在内的多个载荷,海表面温度(SST)是SMR的主要产品之一。本文分别利用NOAA提供的i Quam实测海温数据、CORIOLIS卫星WindSat反演的海温遥感产品、NCEP模式海温数据,在两个典型区域,对2020年1月1日至12月31日期间的HY-2B/SMR海温产品进行了验证,其中HY-2B/SMR与iQuam实测海温的Bias为0.004℃,RMSE约为0.65℃,CORR高于0.95。通过进一步分析,由区域A的分析结果总结了HY-2B/SMR海温产品精度随纬度变化的规律及其原因,同时,由区域B的分析结果计算出陆地、岛礁以及RFI对海温总体反演精度的影响约为0.1℃。

CMIP5 analysis of the interannual variability of the Pacific SST and its association with the Asian-Pacific oscillation

This study analyzed the interannual variability of sea surface temperature （SST） over the Pacific in the historical simulation and under the Representative Concentration Pathways （RCPs, including RCP4.5 and RCPS.5） from 27 models archived in the Coupled Model Intercomparison Project Phase 5 （CMIPS）. Its association with the Asian-Pacific oscillation （APO） was also investigated.The evaluation results showed that the multi-model ensemble mean （MME） and most of the individual models perform well in reproducing the relatively stronger interannual variability of SST over the North Pacific and tropical eastern Pacific. They can also capture reasonably well the observed in-phase and out-of-phase relationships of the APO with the SST in the above two regions, respectively. Under the RCP4.5 and RCPS.5 scenarios, the interannual variability of the SST over the North Pacific and the tropical eastern Pacific is projected by the MME to be weakened during 2050-99 compared to 1950-99. The majority of the CMIP5 models show the same projection as the MME. Besides, the MME projection indicates that the present relationship between the APO and the SST over those two regions would still be dominant under both RCPs. However, considerable discrepancies exist in the changes of the relationships among the individual models.

Future projection of East China Sea temperature by dynamic downscaling of the IPCC_AR4 CCSM3 model result

Future temperature distributions of the marginal Chinese seas are studied by dynamic downscaling of global CCSM3 IPCC_AR4 scenario runs. Different forcing fields from 2080-2099 Special Report on Emissions Scenarios （SRES） B1, A1, and A2 to 1980-1999 20C3M are averaged and superimposed on CORE2 and SODA2.2.4 data to force high-resolution regional future simulations using the Regional Ocean Modeling System （ROMS）. Volume transport increments in downscaling simulation support the CCSM3 result that with a weakening subtropical gyre circulation, the Kuroshio Current in the East China Sea （ECS） is possibly strengthened under the global wanning scheme. This mostly relates to local wind change, whereby the summer monsoon is strengthened and winter monsoon weakened. Future temperature fluxes and their seasonal variations are larger than in the CCSM3 result. Downscaling 100 years＇ temperature increments are comparable to the CCSM3, with a minimum in B1 scenario of 1.2-2.0~C and a maximum in A2 scenario of 2.5-4.5~C. More detailed temperature distributions are shown in the downscaling simulation. Larger increments are in the Bohai Sea and middle Yellow Sea, and smaller increments near the southeast coast of China, west coast of Korea, and southern ECS. There is a reduction of advective heat north of Taiwan Island and west of Tsushima in summer, and along the southern part of the Yellow Sea warm current in winter. There is enhancement of advective heat in the northern Yellow Sea in winter, related to the delicate temperature increment distribution. At 50 meter depth, the Yellow Sea cold water mass is destroyed. Our simulations suggest that in the formation season of the cold water mass, regional temperature is higher in the future and the water remains at the bottom until next summer. In summer, the mixed layer is deeper, making it much easier for the strengthened surface heat flux to penetrate to the bottom of this water.

Evaluation and Preprocess of Chinese Fengyun-3A Sea Surface Temperature Experimental Product for Data Assimilation

Validated satellite-derived sea surface temperatures (SSTs) are widely used for climate monitoring and ocean data assimilation systems. In this study, the Fengyun-3A (FY-3A) SST experimental product is evaluated using Advanced Very High Resolution Radiometer (AVHRR)-merged and in situ SSTs. A comparison of AVHRR-merged SSTs reveals a negative bias of more than 2K in FY-3A SSTs in most of the tropical Pacific and low-latitude Indian and Atlantic Oceans. The error variance of FY-3A SSTs is estimated using three-way error analysis. FY-3A SSTs show regional error variance in global oceans with a maximum error variance of 2.2 K in the Pacific Ocean. In addition, a significant seasonal variation of error variance is present in FY-3A SSTs, which indicates that the quality of FY-3A SST could be improved by adjusting the parameters in the SST retrieval algorithm and by applying regional and seasonal algorithms, particularly in key areas such as the tropical Pacific Ocean. An objective analysis method is used to merge FY-3A SSTs with the drifter buoy data. The errors of FY-3A SSTs are decreased to-0.45K comparing with SST observations from GTSPP.