NASA GES DISC Commitment to the Hydrology Community

:A “Digital Divide” in data representation exists between the preferred way of data access by the hydrology community (i.e., as time series of discrete spatial objects) and the common way of data archival by NASA earth science data centers (i.e., as continuous spatial fields, one file per time step).
This Divide has been an obstacle between hydrology data users (e.g., CUAHSI HIS, HydroShare) and the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC).
The GES DISC (one of 12 NASA Earth Observing System (EOS) data centers) processes, archives, documents, and distributes data from Earth science missions and related projects, including hydrologic land surface data. The latter are part of the GES DISC Water & Energy Cycle data holdings.
Of the many related data services available to users, the NASA Giovanni (Geospatial Interactive Online Visualization and Analysis Infrastructure) is the best known and most used (cited in more than 2000 peer-reviewed research publications).
Giovanni provides a relatively simple way for researchers to conduct exploratory investigations with a variety of NASA Earth observation data and related data sets. Among Giovanni’s suite of plotting options, the time series is probably of the most interest to hydrology data users (and is the second most popular among users in general).
However, for optimal access to GES DISC data along the time dimension, the data as archived must be reorganize to some way that is optimal for that mode of access. Given the importance of bridging the Digital Divide, the GES DISC has
(1) developed “Data Rods,” a set of REST endpoints for long time series;
(2) improved the performance of Giovanni’s time series plotting option; and
(3) assisted the University of Texas-Austin in developing and supporting the Data Rods Explorer (DRE), a HydroShare app that combines data from the first two sources.
As part of NASA data centers’ overall transitioning to the cloud, the GES DISC has been investigating “Giovanni in the cloud.” Though still under development, the prototype Giovanni Cloud-Optimized Data Store (CODS) has already demonstrated a significant performance increase in time series capabilities—5-10 times faster than the current Data Rods endpoints.
The GES DISC aims to continually explore and implement appropriate technologies to improve its data services, in response to user needs of the hydrology community.

数据表征层面存在一道“数字鸿沟（Digital Divide）”：水文学界偏好的数据访问方式为离散空间对象的时间序列形式，而NASA地球科学数据中心通用的数据归档方式则为连续空间场形式，即每个时间步对应一个文件，二者之间形成了这道数字鸿沟。

这道数字鸿沟已成为水文学数据使用者（如CUAHSI HIS、HydroShare）与NASA戈达德地球科学数据与信息服务中心（GES DISC）之间的协作阻碍。

GES DISC作为NASA地球观测系统（Earth Observing System, EOS）旗下12个数据中心之一，负责处理、归档、著录并分发地球科学任务及相关项目的数据，其中涵盖水文陆地表面数据，这类数据属于GES DISC水资源与能量循环数据馆藏的组成部分。

在面向用户的诸多相关数据服务中，NASA Giovanni（地理空间交互式在线可视化与分析基础设施，Geospatial Interactive Online Visualization and Analysis Infrastructure）是知名度最高、使用最广泛的服务，相关成果已被2000余篇同行评议研究论文引用。

Giovanni为研究人员提供了相对简便的途径，使其可借助多种NASA地球观测数据及相关数据集开展探索性研究。在Giovanni的众多绘图选项中，时间序列绘图或许是水文学数据使用者最关注的功能，同时也是全体用户中第二受欢迎的功能类型。

然而，若要沿时间维度最优地访问GES DISC的数据，现有归档格式的数据必须经过重组，以适配该访问模式的最优需求。鉴于弥合数字鸿沟的重要性，GES DISC已完成三项工作：
1. 开发“数据棒（Data Rods）”——一套面向长时序数据的REST接口；
2. 优化了Giovanni的时间序列绘图功能性能；
3. 协助德克萨斯大学奥斯汀分校开发并支持“数据棒浏览器（Data Rods Explorer, DRE）”，这是一款整合了前两类数据源的HydroShare应用。

作为NASA数据中心整体向云平台迁移的一部分，GES DISC一直在探索“云端Giovanni”方案。尽管仍处于开发阶段，原型系统Giovanni云优化数据存储（Cloud-Optimized Data Store, CODS）已展现出时序数据处理能力的显著提升——相较于当前的Data Rods接口，处理速度提升5至10倍。

GES DISC旨在持续探索并落地适配的技术方案，以改进其数据服务，响应水文学界的用户需求。