WArming and irRadiance Measurement (WARM) buoys deployed in Beaufort Shelf and Canada Basin, Arctic Ocean. 2017

The WArming and irRadiance Measurement (WARM) buoy collects measurements of light, temperature, salinity and phytoplankton abundance under the Arctic sea ice. The Arctic ice pack has suffered continued thinning and reduction in seasonal extent, resulting in changes to the amount of sunlight penetrating through the ice and into the ocean beneath, having consequences for the physical and biological environment. Sunlight absorbed by the ocean under the ice causes warming, which can lead to accelerated ice melt resulting in even more sunlight reaching the ocean. In addition, warmer water also affects living organisms, influencing the ability of Arctic adapted species to survive, and possibly promoting the northward advancement of sub-Arctic species. Thinner ice also increases light available for photosynthesis, affecting the timing of phytoplankton blooms. If phytoplankton growth occurs early in the season then zooplankton, the organisms that feed on them can miss the bloom with consequences for the entire food web of the Arctic. This project aims to provide observations to help determine how the under-ice environment is changing by using autonomous buoys which overcome the limitations of ship-based observations. The buoys have proven to be very robust and can survive for approximately one year, providing hourly observations which will be available in near-real time to the research community and interested public parties. The buoys will be deployed in early spring in the western Beaufort Sea, with anticipated drift west over the Chukchi Shelf. This project will continue the WARM buoy initiative by improving the existing design to include increased vertical resolution of temperature and light measurements, the addition of salinity measurement to enable water mass identification, and a second fluorometer to identify sinking phytoplankton biomass. The data collected will provide a time series of important physical and biogeochemical properties over a complete seasonal cycle. It will enable us to address questions related to the effects of a thinner and more open ice pack on the absorption of solar radiation, ocean heating, the phenology of pelagic primary production, and carbon cycling. The buoys have proven to be very robust and can survive for approximately one year, providing hourly observations which will be available in near real time to the research community and interested public parties. The buoys will be deployed in early spring in the western Beaufort Sea, with anticipated drift west over the Chukchi Shelf. The Arctic ice pack acts as a barrier controlling the availability of ultraviolet (UV) and visible light to the water column. Continued thinning and reduction of seasonal Arctic ice has resulted in alterations in the timing and magnitude of solar radiation penetrating the upper Arctic Ocean. Amplification of solar radiation absorption into the ocean acts to warm and stratify the surface layer, which can induce further ice retreat and delay fall freeze-up. Resulting thermal stratification affects the ecosystem by limiting vertical replenishment of nutrients with a direct consequence on the magnitude of primary production. A warmer water column can also play a fundamental role in setting thresholds for the abundance and distribution of plankton communities, affecting trophic efficiency and promoting the northward advancement of sub-Arctic species. Thinner ice increases the light available for photosynthesis and net primary production, affecting the timing of primary production. Small timing mis-match between phytoplankton blooms and zooplankton reproductive cycles can have consequences for the entire lipid-driven Arctic marine ecosystem. Changes in the duration of UV exposure through longer open water periods has the potential to increase photochemical remineralization of terrestrial and marine organic matter and production of labile organic material that can be used by microbes. Determining the impact of solar radiation changes on warming, primary production, and photochemistry are all critical in assessing and predicting the effects of climate change on the marine carbon cycle. The measurement of these variables within and beneath the seasonal ice pack is challenging due to the limitations of ship based observations, but this can be resolved by using the autonomous WARM buoys deployed within the ice and designed to survive ice melt. Data from ice-tethered buoys deployed on Arctic sea ice in March 2017. Data measured include, Photosynthetically available radiation, temperature, and salinity. Sidekicks were deployed coincidently with the WARM buoys and measured surface Photosynthetically available radiation.升温与辐照度测量（WArming and irRadiance Measurement，简称WARM）浮标用于采集北极海冰下方的光照、温度、盐度以及浮游植物丰度数据。北极海冰持续变薄，季节性海冰范围不断缩减，导致穿透海冰进入下方海洋的日照总量发生变化，进而对物理与生物环境造成影响。海冰下方的海洋吸收日照后会升温，这会加速海冰融化，进而让更多日照能够抵达海洋。此外，水温升高还会影响海洋生物，削弱适应北极环境的物种的生存能力，并可能推动亚北极物种向北扩张分布范围。海冰变薄还会增加可供光合作用利用的光照量，进而影响浮游植物水华的发生时间。如果浮游植物在季节早期就开始繁殖，那么以其为食的浮游动物可能会错过水华期，这将对北极整个食物网造成连锁影响。本项目旨在通过自主浮标开展观测，以厘清冰下环境的变化趋势，而这类浮标能够克服船基观测的局限性。目前该类浮标已被证实具有极高的可靠性，可连续工作约一年，能够每小时采集一次观测数据，并以近实时的方式向科研群体及关注该领域的公众开放。本次浮标将在早春时节部署于波弗特海西部海域，预计将向西漂移横跨楚科奇海台。本项目将对现有WARM浮标设计进行升级，以延续该浮标观测计划：提升温度与光照测量的垂直分辨率，新增盐度测量模块以实现水团识别，并增设第二台荧光计以检测沉降的浮游植物生物量。采集到的数据将形成完整季节周期内关键物理与生物地球化学属性的时间序列，可用于解答以下科学问题：海冰变薄、海冰覆盖范围缩减对太阳辐射吸收、海洋升温、浮游植物初级生产物候以及碳循环的影响。目前该类浮标已被证实具有极高的可靠性，可连续工作约一年，能够每小时采集一次观测数据，并以近实时的方式向科研群体及关注该领域的公众开放。本次浮标将在早春时节部署于波弗特海西部海域，预计将向西漂移横跨楚科奇海台。北极海冰作为一道屏障，控制着水柱可获取的紫外（UV）与可见光辐射量。北极季节性海冰持续变薄与范围缩减，已改变了穿透北极上层海洋的太阳辐射的时间与强度。海洋对太阳辐射吸收的增强会导致表层海水升温并形成层结，进而引发海冰进一步消退，并推迟秋季的海冰冻结时间。由此产生的热层结会限制营养盐的垂直补给，进而影响初级生产的规模，对海洋生态系统造成影响。水温升高的水柱还会从根本上决定浮游生物群落的丰度与分布阈值，影响营养级效率，并推动亚北极物种向北扩张。海冰变薄会增加可供光合作用与净初级生产利用的光照量，进而影响初级生产的发生时间。浮游植物水华与浮游动物繁殖周期之间微小的时间错配，就可能对整个依赖脂质的北极海洋生态系统造成影响。由于无冰期延长，紫外线暴露时长发生变化，这可能会增强陆地与海洋有机质的光化学再矿化作用，并生成可被微生物利用的易降解有机物质。厘清太阳辐射变化对升温、初级生产以及光化学过程的影响，对于评估和预测气候变化对海洋碳循环的影响至关重要。由于船基观测存在局限性，在季节性海冰内部及下方开展上述变量的测量极具挑战性，但通过部署于海冰之中、专为耐受海冰融化而设计的自主WARM浮标，这一难题可得到解决。2017年3月，曾在北极海冰上部署系留浮标，采集的数据包括光合有效辐射、温度与盐度。同期还部署了Sidekicks浮标，用于测量表层光合有效辐射。