MUMM/GRIMAS time series extraction tool

Description

This interface allows you to easily request time-series from the remote sensing data archives at MUMM. Currently data from MODIS Aqua (2002-2011), MERIS (2002-2011) and SeaWiFS (1997-2004) are available for two regions, the Southern North Sea and Thames Estuary (SNSTH) and the Southern North Sea and English Channel (SNC). The following parameters can be extracted: chlorophyll a (CHL) and total suspended matter (TSM) concentrations from MODIS, MERIS and SeaWiFS and sea surface temperature (SST) from MODIS.

Details on the processing can be found in:

Vanhellemont Q., Nechad B. & Ruddick K. (2011). GRIMAS: Gridding and Archiving of Satellite-Derived Ocean Colour Data for any Region on Earth. In: Proceedings of the CoastGIS 2011 conference held in Ostend, 5 - 8 September, 2011. Download

Nechad B. & Ruddick K. & Neukermans G. Calibration and validation of a generic multisensor algorithm for mapping of turbidity in coastal waters (2009) SPIE "Remote Sensing of the Ocean, Sea Ice, and Large Water Regions" Conference held in Berlin (Germany), 31 August 2009. Proc. SPIE Vol. 7473, 74730H Download

MODIS data has been updated to reprocessing version R2012.0.

How to order data?

  1. Select one of the backgrounds and select your location. These backgrounds are MODIS Aqua climatologies of TSM and CHL for SNSTH or SNC. A dark grey border around the land shows where the data from MODIS is always masked due to proximity to land (stray light). You can click on the map to select a point, or alternatively, you can enter latitude/longitude values (decimal degrees) for your point, or choose a predefined station. The background will revert to SNSTH when selecting a predefined location, as they are all within this region.
  2. Select sensors and products. SST is only available from MODIS (2002-2011), while CHL and TSM are available from MODIS, MERIS (2002-2011) and SeaWiFS (1997-2004).
  3. Enter dates and check the "range" box if appropriate, i.e. when data has to be extracted from the first date up to and including the last. For example, when requesting the dates 2002,200601 without the range box checked you will receive the data from 2002 and January 2006. With the range box checked you will receive data from 2002,2003,2004,2005 and January 2006.
  4. Enter your e-mail address, fill out the spam-filter box and click on the "Get timeseries" button. You will receive an email with the data when the extraction is complete. This can take a variable amount of time, depending on the amount of data that needs to be processed for your order and whether there are other pending requests.

How to use the data?

If your request is successfully handled you will receive the results within a compressed archive. There are two .png images, one with a rough plot of the time-series data and one with a map showing the location of the requested station. For each sensor there is a .csv file with the extracted data. Values are stored using a comma as separator and a point as decimal point (take note, Belgian users!). The first two rows of the .csv file contain information about the contents (sensor, region, parameters, coordinates and date range) and the third row contains a header for the data that starts at row four. Each record includes date (YYYYMMDD), day of year, hour and minutes of the satellite image. Then for each parameter, five values are included: the value of the image pixel over the requested station (PIX_VALUE), the number of valid pixels in a five-by-five box over the station (KERN_COUNT), and the median, mean and standard deviation of the valid pixels in this box (KERN_MEDIAN, KERN_MEAN, KERN_SDEV). The number of valid pixels can be useful to determine data quality, and the median can be used to increase data availability as sometimes data can be missing for the station pixel. For example, the included plots are made using the kernel median value of the kernels containing 13 or more valid pixels.

Click image to enlarge

Data extraction form

 
The background is only an illustration to help you pick out a location. Choose parameters to extract using the Parameters checkboxes below.
Decimal degrees
Decimal degrees
Separate different periods with a comma. Date format: e.g. 2006, 200711, 20081205
To extract a continuous range, enter exactly TWO dates in the field above and select yes here

Disclaimer

While the Remote Sensing and Ecosystem Modelling (REMSEM) team of the Royal Belgian Institute of Natural Sciences (RBINS) has made efforts to ensure best available quality of this data, neither RBINS, nor any person acting on their behalf is responsible for the use, which may be made of the information. Users are encouraged to report any questions or problems regarding data quality.

The MODIS TSM product is validated in the SNSTH region (Nechad et al. 2010, 2011) and the SST product is also well correlated with in situ seawater temperature (Vanhellemont & Ruddick, 2011). Remote sensing of chlorophyll concentration has its limitations in turbid and coastal waters, so for the largest part of this dataset, chlorophyll data should be used with caution. However, good results are obtained for the timing and spatial extent of the chlorophyll maximum during the spring phytoplankton bloom. The time-series extraction is done by an automated system that we try to keep running, but periods of unscheduled downtime can occur during which no requests will be handled.

MODIS and SeaWiFS data were provided by NASA, and MERIS data was provided by ESA.