Warming and Radiance 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.升温与辐射测量（WArming and irRadiance Measurement, WARM）浮标可采集北极海冰下方的光照、温度、盐度及浮游植物（phytoplankton）丰度数据。北极海冰盖持续变薄、季节性覆盖范围不断缩减，导致穿透海冰进入下方海洋的太阳光总量发生改变，进而对海洋物理与生物环境造成影响。海冰下方的海洋吸收太阳光后会引发升温，加速海冰融化，使得更多太阳光能够抵达海洋，形成正反馈循环。此外，水温升高会对海洋生物产生影响，降低适应北极环境的物种的生存能力，还可能推动亚北极物种向北扩张。海冰变薄同样会增加可供光合作用利用的光照量，改变浮游植物水华的发生时序。若浮游植物提前进入生长期，以其为食的浮游动物（zooplankton）可能错过摄食窗口期，进而对北极全域食物网产生连锁影响。 本项目旨在通过自主浮标获取观测数据，以弥补船基观测的局限性，助力探明冰下环境的变化趋势。该浮标已被证实具备极高的可靠性，可连续运行约一年，每小时采集一次观测数据，且数据将以近实时的形式向科研社区及关注相关研究的公众开放。浮标将于早春部署于波弗特海西部，预计将随海冰向西漂移，途经楚科奇海架。 本项目将延续WARM浮标计划，对现有浮标设计进行升级：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（water mass）识别，增设第二台荧光计（fluorometer）以检测沉降的浮游植物生物量。所采集的数据将提供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，助力我们解答以下科学问题：海冰变薄、覆盖范围缩减对太阳辐射吸收、海洋升温、浮游初级生产力物候以及碳循环的影响。 该浮标已被证实具备极高的可靠性，可连续运行约一年，每小时采集一次观测数据，且数据将以近实时的形式向科研社区及关注相关研究的公众开放。浮标将于早春部署于波弗特海西部，预计将随海冰向西漂移，途经楚科奇海架。 北极海冰盖作为一道屏障，控制着水柱可获取的紫外线（Ultraviolet, UV）与可见光总量。北极季节性海冰的持续变薄与覆盖范围缩减，已改变了穿透北极上层海洋的太阳辐射的时序与强度。海洋对太阳辐射吸收的增强会导致表层海水升温并形成热层化，进而引发海冰进一步消退，推迟秋季海冰冻结。由此产生的热层化会限制营养盐的垂直补充，直接影响初级生产力的规模，进而对海洋生态系统造成影响。水温升高的水柱还会在设定浮游生物群落丰度与分布阈值方面发挥基础性作用，降低营养级效率，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力利用的光照量，改变初级生产力的发生时序。浮游植物水华与浮游动物繁殖周期的微小时序错配，就可能对整个依赖脂质的北极海洋生态系统产生严重影响。随着无冰期延长，紫外线暴露时长的变化有可能增强陆地与海洋有机质的光化学再矿化过程，并生成可供微生物利用的易降解有机质。明确太阳辐射变化对海洋升温、初级生产力及光化学过程的影响，是评估与预测气候变化对海洋碳循环影响的关键环节。 在季节性海冰内部及下方开展上述变量的观测极具挑战，这源于船基观测的局限性，但通过部署于海冰内部、专为适应海冰融化环境设计的自主WARM浮标，这一难题可得到解决。 2017年3月，科研人员曾在北极海冰上部署冰系留浮标，所采集的数据包括光合有效辐射（Photosynthetically available radiation）、温度与盐度。同期还部署了Sidekick浮标，用于测量表层光合有效辐射。