Introduction

About the Cesar Database

The Cabauw Experimental Site for Atmospheric Research (Cesar) has been established in 2002. It is a consortium of presently eight institutes and universities located in the Netherlands. The goal of the consortium is to operate and maintain at the Cabauw site a unique observational facility with a comprehensive set of remote sensing and in-situ equipment to characterize the state of the atmosphere, its radiative properties and the interaction with the land surface. The principal use of the measurements is 1) to study physical and chemical processes, 2) climate monitoring and 3) to perform validation studies.

Timely delivery and accessibility of the data collected is of great importance for all users of Cesar data. The option of early comparison of data acquired during the Cesar continuous operational program or intensive field campaigns leads to improved understanding of instrument performance and improvements in the observational data stream. Also scientists not directly involved in the acquisition of the observational data benefit by timely access to the acquired data to accelerate their own research programs and can, on the other hand, contribute to the field program by a feedback on data quality or improved observational strategies. Early sharing of available data helps to ensure that the full benefit from the Cesar observations is realized. This can only be successful if the data are accessible, well documented and archived. Therefore the Cesar consortium initiated a project to develop, operate and maintain a central webportal for access to the Cesar Observatory products.

The webportal and database were developed by the Royal Netherlands Meteorological Instititute (KNMI) in cooperation with and feedback from the Cesar partners. The KNMI also hosts and maintains the webportal and database.

The Cesar webportal and database

Atmospheric, hydrological and other observational data collected at the Cesar Observatory from routine operation, experiments and (intensive observation) campaigns are made available through the Cesar database portal. Also higher order products derived directly or indirectly from the observational data are disseminated through the Cesar database portal.

First time users must register before any data can be ordered and downloaded.

Questions related to the use and/or functionality of the data portal itself should be addressed to the content manager by email (see Contacts). Please check the FAQ list first before sending your question(s) to the content manager.

Data format and convention

All the data are stored in netCDF formatted files and comply with the CF-1.4 convention. Information on the netCDF format and CF-1.0 convention can be obtain from the internet. Links to the homepage of both the netCDF and CF-convention websites are listed under 'Links' in the menu on the right.

The quicklooks are only for display in the webportal, these cannot be ordered. The format is mostly png, but jpg or gif are also supported. The size of the quicklooks is fixed to 600 x 400 px.

The dataset description files which give a detailed explanation of the equipment, data-acquisition, processing and quality control, are stored in pdf format.

Browsing metadata

You can browse the metadata in two ways. You can use either the Search datasets option to search for specific data, or use Browse categories to get an overview of all available datasets.

The Search datasets option allows to search for days characterized by a number of variables e.g. daily mean temperature or maximum wind speed. Presently up to three search variables and their minimum and/or maximum value can be selected.

You can also use a selection based on a time window, or search on specific keywords. On the Search datasets page you will find a link to a more comprehensive explanation.

Ordering data products

Once you have selected data products of interest, you add these to your basket. When you have added all the products of interest to your basket you can order your basket. On receiving an order via the webportal the system will retrieve the products from the database and add all the data files into one single tar file. This tar file is compressed using the gzip compression. The size of a single order is limited (see the FAQ page). When this process is finished you will receive a notification by email with a link to your file. The tar file will remain available for download for a week. After a week the tar file is removed. You can monitor the status of your order when you login and go to 'my Cesar'.

Dataset metadata

Information on a dataset can be viewed when clicking on the i icon located to the right of a dataset listing. The metadata presented are based amongst others on the WMO and INSPIRE recommendations. In this metadata list you will find a link to supplemental information. The URL provided here is a link to the dataset description file (in pdf format) in which the data provider explains in more detail e.g. the sensor/system specifications, calibration method, maintenance procedures, data acquisition, quality control procedures and/or processing of the data.

It is highly recommended to download and read the system description file first before ordering products of the dataset and/or contacting the data provider for questions about the data product.

Site navigation

For navigation you can use the menu on the right hand side, links on the pages or use the bread crumb trail on top of the main window.