ABSTRACT

Water quality in estuarine and coastal waters of Aotearoa New Zealand is of concern yet currently under-monitored, reflecting challenges of sampling at regular intervals across large areas. Satellite products are currently underutilised (globally) by management agencies but could be part of a holistic approach. NIWA-SCENZ (Seas, Coasts and Estuaries New Zealand) is a website providing access to MODIS-Aqua products at moderate spatial resolution (500 m) across relatively clear coastal waters (Case 1) to turbid coastal waters (Case 2). It also provides advanced analytical tools on an extracted area of interest for trend assessment (Shiny-SCENZ). For Case 1 areas product accuracy will be comparable to data from other websites using the same algorithms. For Case 2 and transition (blended) areas, although tuned to New Zealand conditions, accuracy of products requires validation. Data availability is mainly impacted by cloud cover, but also adjacency to land and bottom reflection. On average <5% within ∼1 km from coastlines, compared to ∼10%–30% outside 2 km. Extrapolation and blending from offshore into shorelines on month averaged maps extend estimates into many bays and estuaries. Active research efforts will deliver iterative improvements in data quality, new products, and analysis methods (e.g. variability and long-term trend maps).

摘要

新西兰 Aotearoa 河口和沿海水域的水质令人担忧，但目前监测不足，这反映了在大面积定期采样的挑战。管理机构目前（全球）未充分利用卫星产品，但可以作为整体方法的一部分。NIWA-SCENZ（新西兰海洋、海岸和河口）是一个网站，提供在相对清澈的沿海水域（案例 1）到混浊的沿海水域（案例 2）以中等空间分辨率（500 m）访问 MODIS-Aqua 产品的途径。它还为趋势评估 (Shiny-SCENZ) 提供了对提取的感兴趣区域的高级分析工具。对于案例 1 领域，产品准确性将与使用相同算法的其他网站的数据相媲美。对于案例 2 和过渡（混合）区域，尽管根据新西兰的情况进行了调整，产品的准确性需要验证。数据可用性主要受云量影响，但也受陆地和底部反射的影响。在距海岸线约 1 公里范围内平均 <5%，而在 2 公里以外则为 10%–30%。在月平均地图上从近海到海岸线的外推和融合将估计值扩展到许多海湾和河口。积极的研究工作将在数据质量、新产品和分析方法（例如可变性和长期趋势图）方面提供迭代改进。