1. Introduction

1.1. Motivation

Earth observations (EOs) are usually produced and treated as 3-dimensional singular data cubes, i.e. for each longitude u ∈ {1, ..., Lon}, each latitude v ∈ {1, …, Lat}, and each time step t ∈ {1,...,T} an observation X = {x(u,v,t)} ∈ R is defined. The challenge is, however, to take advantage of the numerous EO streams and to explore them simultaneously. Hence, the idea is to concatenate data streams such that we obtain a 4-dimensional data cube of the form x(u,v,t,k) where k ∈ {1, …, N} denotes the index of the data stream. The focus of this project is therefore on learning how to efficiently and reliably create, curate, and explore a 4-dimensional Earth System Data Cube (ESDC). If feasible, the included data-sets contain uncertainty information. Limitations associated with the transformation from source format into the ESDC format are explained in the description of the data sets. The ESDC does not exhibit spatial or temporal gaps, since gaps in the source data are filled during ingestion into the ESDC. While all observational values are conserved, gaps are filled with synthetic data, i.e. with data that is created by an adequate gap-filling algorithm. Proper data flags ensure an unambiguous distinction between observational and synthetic data values.

Depending on the specific question, the user can extract different types of data subsets from the Earth System Data Cube (ESDC) for further processing and analysis with specialized methods from the Data Analytics Toolkit. For example,

  • investigating the data cube at a single geographic location, the user obtains multivariate time series for each longitude-latitude pair. These time series can be investigated using established methods of multivariate time series analysis, and afterwards the results can be merged onto a global grid again.
  • Assessing the data-cube at single time stamps results in synoptic geospatial maps, whose properties can be investigated with geostatistical methods.
  • It is also possible to perform univariate spatiotemporal analyses on single variables extracted from the Data Cube.
  • The main objective is, however, to develop multivariate spatiotemporal analyses by utilizing the entire 4D ESDC. Following this avenue unravels the full potential of the ESDC and may provide a holistic view on the entire Earth System.

The ESDC allows for all these approaches, because all variables are available on a common spatiotemporal grid, which greatly reduces the pre-processing efforts typically required to establish consistency among data from different sources.

1.2. ESDC Project

The steadily growing Earth Observation archives are currently mostly investigated by means of disciplinary approaches. It would be, however, desirable to adopt a more holistic approach in understanding land-atmosphere interactions and the role of humans in the earth system. The potential of a simultaneous exploration of multiple EO data streams has so far been widely neglected in the scientific community. The Earth System Data Cube project (ESDC, formerly CAB-LAB) aims at filling this gap by providing a virtual laboratory that facilitates the co-exploration of multiple EOs for a better understanding of land ecosystem trajectories.

The idea is to build on the existing data-sets and to offer novel tools and technical methods to detect dependencies in the coupled human-nature system. ESDC’s central service to the scientific community will be a Biosphere Atmosphere Virtual Laboratory (BAVL), which comprises a Data Cube populated with a wide range of EOs and convenient methods to access and analyze this data remotely by means of the Jupiter framework. Moreover, the project aims at advancing the scientific analysis capacities by developing data-driven exploration strategies that identify and attribute major changes in the biosphere-atmosphere system. Ultimately, ESDC will develop a set of indices characterizing the major relevant Biosphere-Atmosphere System Trajectories, BASTs. The project partners, Max-Planck-Institute for Biogeochemistry, Brockmann Consult GmbH, and Stockholm Resilience Center are financed by the European Space Agency (ESA) for three years (2015 to 2017) to develop the software for ESDC, to collect and analyze the EO data, and to disseminate the idea of the project and its preliminary results.

1.3. Purpose

This Product Handbook is a living document that is under active development just as the ESDC project itself. Its purpose is to facilitate the usage of the BAVL and primarily targets scientists from various disciplines with a good command of one of the supported high-level programming languages (Python, Julia, and R), a solid background in the analysis of large data-sets, and a sound understanding of the Earth System. The focus of this document is therefore clearly on the description of the data and on the methods to access and manipulate the data.

In the final version, it is meant to be a self-contained documentation that enables the user to independently reap the full potential of the Earth System Data Cube (ESDC). Developers may find a visit of the project’s git-hub pages worthwile.

1.4. Scope

The Product Handbook gives a general overview of the ESCD’s structure and provide some examples to illustrate potential uses of the system . The main part is considered with a detailed technical description of the ESDC , which is accompanied by the full specification of the API. Finally, all data-sets included in the ESDC are listed and described in the annex of the Product Handbook.

1.5. References

  1. ESDC webpage: http://www.earthsystemdatacube.net
  2. CAB-LAB’s github repository: https://github.com/CAB-LAB
  3. E-Laboratory: https://cablab.earthsystemdatacube.net

1.6. Peer-reviewed Publications

Sippel, S., Lange, H., Mahecha, M. D., Hauhs, M., Bodesheim, P., Kaminski, T., Gans, F. & Rosso, O.A. (2016) Diagnosing the Dynamics of Observed and Simulated Ecosystem Gross Primary Productivity with Time Causal Information Theory Quantifiers. PLoS ONE, accepted. doi:10.1371/journal.pone.0164960.

Sippel, S., Zscheischler, J., Heimann, M., Otto, F. E. L., Peters, J., & Mahecha, M. D. (2015), Quantifying changes in climate variability and extremes: Pitfalls and their overcoming, Geophysical Research Letters, 42(22), 9990–9998. doi:10.1002/2015GL066307.

Sippel, S., Zscheischler, J., Heimann, M., Lange, H., Mahecha, M. D., van Oldenborgh, G. J., Otto, F. E. L. & Reichstein, M. (2016) Have precipitation extremes and annual totals been increasing in the world’s dry regions over the last 60 years? Hydrology and Earth System Sciences Discussions. doi:10.5194/hess-2016-452.

Flach, M., Gans, F., Brenning, A., Denzler, J., Reichstein, M., Rodner, E., Bathiany, S., Bodesheim, P., Guanche, Y., Sippel, S., and Mahecha, M.D. Multivariate Anomaly Detection for Earth Observations: A Comparison of Algorithms and Feature Extraction Techniques. Earth System Dynamics – Discussions, doi:10.5194/esd-2016-51.

1.7. Terms and Abbreviations

Term Description
BAST Biosphere-Atmosphere System Trajectory
BAVL Biosphere Atmosphere Virtual Laboratory
CAB-LAB Coupled Atmosphere Biosphere virtual LABoratory
DAT Data Analytics Toolkit
ESDC Earth System Data Cube
EO Earth Observations
ESA European Space Agency
Grid The Data Cube’s layout given by its spatial and temporal resolution and its variables.
Image An 2D data cube subset with dimension (lat, lon)

1.8. Data Policy

The ESDC team processes and distributes the data in the ESDC in good faith, but makes no warranty, expressed or implied, nor assumes any legal liability or responsibility for any purpose for which the data are used. In particular, the ESDC team does not claim ownership of the data distributed through the ESDC nor does it alter the data policy of the data owner. Therefore, the user is referred to the data owner for specific questions of data use. References and more details of the data sets are listed in the annex of the Product Handbook.

The CAB-LAB team is thankful to have received permissions for re-distribution of all data contained in the ESDC from the respective data owners.

Note

Please cite the ESDC as:

The ESDC developer team (2016). The Earth System Data Cube (Version 0.1), available at: https://github.com/CAB-LAB.