The North American summer monsoon (NASM) and the North African summer monsoon (NAFSM) are two vital subsystems of the global monsoon. To date, the potential inter-monsoon relationship between the NASM and NAFSM has not been fully understood. To fill this gap, we investigate the NASM-NAFSM relationship on the interannual timescale during the period of 1979-2022. Based on statistical methods (including correlation, empirical orthogonal function and cross wavelet analyses), we identify a noteworthy interannual covariation of the NASM and NAFSM. This observed NASM-NAFSM covariation can be explained by atmospheric circulation anomalies associated with sea surface temperature (SST) anomalies in the tropical central-eastern Pacific and tropical Atlantic, suggesting the critical roles of tropical Pacific-Atlantic SST anomalies in shaping the NASM-NAFSM covariation. The results of Coupled Model Intercomparison Project Phase 6 (CMIP6) models indicate that a model's ability to simulate the NASM-NAFSM covariation tends to be related to its ability to reproduce the modulating effects of the tropical Pacific-Atlantic SST anomalies. These results have potential implications for seasonal forecasts of the NASM and NAFSM variations, suggesting that the NASM and NAFSM can be considered simultaneously in climate predictions. This study identifies a noteworthy interannual covariation of the North American summer monsoon (NASM) and the North African summer monsoon (NAFSM). The NASM-NAFSM covariation can be explained by atmospheric circulation anomalies associated with trans-Atlantic-Pacific dipole-like sea surface temperature (SST) anomalies.image

Variations of the North American summer monsoon (NASM) and North Atlantic tropical cyclone (NATC) activities strongly influence climate anomalies in North America, with serious potential risk to life and property. Despite the scientific importance of this topic, the possible linkage between the NASM and the NATC genesis frequency remains unexplored. Here, we aim to examine the relationship between interannual variations of the NASM intensity and the NATC genesis frequency based on observations and Coupled Model Intercomparison Project Phase 6 (CMIP6) models. Our results show a strong association between the NASM intensity and the NATC genesis frequency during the extended boreal summer, with a good synchronization between their interannual variations. In years with stronger (weaker) NASM intensity, the NATC genesis frequency tends to be higher (lower). The observed NASM–NATC synchronization may be explained by two pathways: tropical-ocean-driven pathway and monsoon-heating-driven pathway. In the tropical-ocean-driven pathway, the tropical Pacific and Atlantic interbasin sea surface temperature (SST) anomalies play a critical role in bridging the NASM and NATC, by modulating the cross-Central American wind. Simulations of the tropical Pacific–Atlantic interbasin SST anomalies are critical for CMIP6 models to capture the observed linkage between the NASM and the vertical wind shear over the NATC main development region (MDR). In the monsoon-heating-driven pathway, the heating source due to the rainfall anomalies associated with the NASM can trigger atmospheric circulation anomalies through the Gill-type response, thereby affecting the NATC by changing the vertical wind shear over the MDR. This study demonstrates a connection between interannual variations of the NASM and the NATC genesis frequency, results of which can be used to advance our understanding of the monsoon–TC relationship and increase research focus on the interannual NASM–NATC synchronization in climate prediction.

为了培养海洋科学与大气科学交叉复合型人才,文章首先说明了"海洋气象学"课程教学目标及教学存在的问题,然后对"海洋气象学"课程教学知识点进行了设计,最后论述了"海洋气象学"课程教学实践.

对比了1979-2020年全球8个主要季风区湿季和干季降雨的长期变化趋势、变率和偏度特征.主要结果如下:(1)在长期变化趋势方面,东亚、西北太平洋和北非季风的湿季降雨以及印度季风的干季降雨呈现显著的增加趋势,而北美和南美季风的干季降雨和南美季风的湿季降雨呈现显著的下降趋势.东亚和北非季风(南美季风)的湿季—干季降雨差值呈现显著的增加(下降)趋势.(2)在变率方面,北美和北非季风湿季和干季降雨的方差在2000-2020年(P2时期)要小于1979-1999年(P1时期);南非和澳洲季风湿季和干季降雨的方差在P2时期要大于P1时期;东亚、西北太平洋和南美季风降雨方差的变化在湿季和干季存在不一致性,湿季(干季)降雨的方差在P2时期增加(减小).(3)在偏度方面,东亚、印度、澳洲和南非季风干季降雨和东亚季风湿季降雨的偏度值在P2时期增加;而西北太平洋季风干季降雨和北非季风湿季降雨的偏度值在P2时期减小.

The western North Pacific summer monsoon (WNPSM) is an important subcomponent of the Asian summer monsoon. The equatorial zonal wind (EZW) in the lower troposphere over the western Pacific may play a critical role in the evolution of the El Niño-Southern Oscillation (ENSO). The possible linkage between the EZW over the western Pacific and the off-equatorial monsoonal winds associated with the WNPSM and its decadal changes have not yet been fully understood. Here, we find a non-stationary relationship between the WNPSM and the western Pacific EZW, significantly strengthening their correlation around the late 1980s/early 1990s. This observed shift in the WNPSM–EZW relationship could be explained by the changes in the related sea surface temperature (SST) configurations across the tropical oceans. The enhanced influence from the springtime tropical North Atlantic, summertime tropical central Pacific, and maritime continent SST anomalies may be working together in contributing to the recent intensified WNPSM–EZW co-variability. The observed recent strengthening of the WNPSM–EZW relationship may profoundly impact the climate system, including prompting more effective feedback from the WNPSM on subsequent ENSO evolution and bolstering a stronger biennial tendency of the WNPSM–ENSO coupled system. The results obtained herein imply that the WNPSM, EZW, ENSO, and the tropical North Atlantic SST may be closely linked within a unified climate system with a quasi-biennial rhythm occurring during recent decades, accompanied by a reinforcement of the WNPSM–ENSO interplay quite possibly triggered by enhanced tropical Pacific–Atlantic cross-basin interactions. These results highlight the importance of the tropical Atlantic cross-basin influences in shaping the spatial structure of WNPSM-related wind anomalies and the WNPSM–ENSO interaction.

In order to resolve the conflict between the temporal and spatial resolution of remote sensing, we plan to construct a virtual satellite constellation by combining multiple satellites with high spatial resolution sensors to improve the temporal resolution. By using satellite-land synchronized data obtained in 4 different offshore regions near China between 2015 and 2017, we evaluated the remote sensing chlorophyll inverse algorithms of different sensors, and further determined a remote sensing inverse model, which is suitable for data of multiple medium-high resolution satellites. By using GOMS/GOCI chlorophyll concentration product as reference, we first projected the chlorophyll concentration values inverted from satellites HJ-1A, HJ-1B, GF-1,GF-4, Landsat 5, Landsat 8 to a 50-m grid by applying flux conservation resampling method. We further applied a recalibration method to obtain recalibration equations, which make the chlorophyll concentration values inverted from different sensors comparable.