BSIK

BSIK-CS8 (Time series information)

Wetenschappelijk projectleider: Theo Brandsma
Technisch Projectleider: Vacature
Start project: februari 2005
Verwachte einddatum : februari 2009

Problem definition and objectives

Datasets are the foundation of studies regarding climate and its impacts. Many impact models run at a (sub)daily time step. These models have usually an empirical character. To understand e.g. the effect of climate on land use, the availability of suitable meteorological datasets is crucial to calibrate and tune both climate models and impact models on the variability of the current climate. Because violent extremes have a dominating impact, time series should be of high resolution not only in space but also in time. Also, to determine probabilities of occurrence of such events, the series should be as long as possible. Contrary to what is generally believed, the climatological frequencies of violent events are hardly known, even for the present state of the climate. In the light of safety design level, it is of utterly importance that quantitative information about this becomes available. The Netherlands is among the few countries where data of sufficient length and temporal resolution is available to empirically estimate this information, but the bulk of this data is only in the form of hard copies.

A large selection is made of the above-mentioned hard copy data, based on its relevance for the climate research and impact communities. The corresponding meteorological observations will be digitized, quality-controlled, homogenized and put in externally accessible user-friendly datasets. Maximal benefit for the entire scientific and impact communities is guarantied by a free and easy access to the data. Relevant statistical properties of the data will be derived to define the current state of the climate, including its extremes. After finishing this large-scale effort, an on-line tool is available to perform impact studies as well as to calibrate models on extreme features of the observed variability of the climate.

The proposed acivities fit into the KNMI program HISKLIM (Historical climate; Brandsma et al., 2000) that aims at at digitization, database building and homogenization of historical records in the Netherlands. The HISKLIM program-description defines all Dutch data sources that still have to be digitized. At present the 19th century KNMI yearbooks and a unique long hourly climate series of Amsterdam (1784-1963) are being digitized. Besides these type of data sources, there are data sources in the program description that can only be digitized when external funds become availble. An example is 17th and 18th century maritime logbooks of which a large part has recently been digitzed and put into a database within the European Union project CLIWOC (CLImatological database for the World’s OCeans 1750-1850; Können and Koek, 2004). Other examples are the data sources proposed here (see Section 5).An important part of the HISKLIM program is the homogenization of the Zwanenburg/De Bilt (1706-present) sub-daily meteorological time series. To complete this task, as many as possible nearby parallel time series are needed. For the 18th and 19th century 1850, the third data source proposed here (see Section 5), provides the homogenization project with the necessary parallel time series. The proposed activities also fit into the work of the Climate Analysis Division of KNMI. This division constructs climate scenarios for present and future climate. The work relies on the existence of suitable long datasets of historical climate data.

The objective of the project is to create new datasets with historical climate data, which at present are only available as hardcopy. These datasets, including the infrastructure to make them electronically accessible, are needed for obtaining knowledge about the current state of the climate, including its extremes. This is needed for understanding and describing the impact of climate on e.g. land use and water management, including the calibration, verification and tuning of (impact) models suitable to describe climate change. The information will be provided in the form of datasets with observed time series of high temporal resolution in a dense network in the Netherlands. This information will be freely and easily available to the scientific and impact community dealing with climate change and its impacts. As far as applicable, the newly digitized datasets will be coupled with the corresponding modern-day data in the Netherlands. It is our aim to make also the resulting extended datasets freely available to the scientific and impact communities dealing with climate change and its impacts. During the project a scientific assessment of the statistical properties of the data is made, mainly fitted to the needs of the impact studies in the CS-7 project (Tailoring climate information for impact assessment applications). Also (scientific) support is given to the CS-7 project with respect to the actual use of the data. The data produced here will also be used to verify the regional climate model in the CS-6 project (Climate scenario calculations of wind and precipitation for the Netherlands with a high-resolution regional climate model).

Expected results

This labor-intensive project will digitize hundreds of time series of meteorological data of the 20th century and before. The data will be quality controlled and be homogenized using standard methods, and made available via internet. Emphasis will be on high spatial and temporal resolution of precipitation and other impact relevant elements. There are 3 main categories of time series that will be made available:

1. Daily precipitation time series 1850-1950

2. High-temporal resolution (5-min) rainfall time series, to be abstracted from pluviographs for the following 6 stations: De Bilt (1897–1993), Eelde (1954–1993), Den Helder/De Kooy (1954–1993), Vlissingen (1954–1993), Beek (1954–1993) and Amsterdam (1920–1983);

3. Sub-daily 18th and 19th century weather series; for a description of these series see Brandsma et al. (2000).