MAMA 6th meeting, Tunis, 7-8 March 2005

Oscar Chic, Roger Olivella and Jordi Font, ICM, CMIMA-CSIC,

Barcelona

SAIDIN (SAtellite Image Database INterface)

MAMA 6th meeting, Tunis, 7-8 March 2005

Introduction• Satellite data traditionally difficult to work with

(telemetry raw formats, large sizes, software to process...)

• Aim to make easy and powerful to work with satellite data.

• Two kind of satellite data users.

– SAIDIN for users looking for qualitative data.– Live Access Server (LAS/Ferret Server allows to

download netCDF raw data) for users looking for quantitative/raw data.

• From image browser to web application

MAMA 6th meeting, Tunis, 7-8 March 2005

MAMA 6th meeting, Tunis, 7-8 March 2005

MAMA 6th meeting, Tunis, 7-8 March 2005

SAIDIN (SAtellite Image Database INterface

MAMA 6th meeting, Tunis, 7-8 March 2005

Features• Near Real Time SST AVHRR NOAA data (1h. update time), historical wind

QuikScat and monthly averaged SeaWIFS chlorophyll.

• Powerful visualization using a synoptic view and a full resolution window.

• Window showing pixel information: latitude, longitude and temperature.

• Choice between different color palettes (black-white, hsl256, zebra) to improve visualization.

• Brightness and contrast enhancement.

• Download images as a zipped or unzipped set.

• Data search using an interactive calendar (http://nachocalendar.sourceforge.net/).

• Log message window.

• Quicklooks (QL) image and metadata information useful to analyze cloud coverage, and image quality.

• Zoom x2.

• Web application could be downloaded to work as a standalone application.

MAMA 6th meeting, Tunis, 7-8 March 2005

Features (in development)

• Daily and night-time temperature mean calculation using maximum pixel value (MPV).

• LAS/Ferret server implementation to allow showing and downloading raw data in netCDF format cointaining AVHRR original channels (cropped to region of interest), sst and land mask.

• Overlaying SST images with bouys temperature information of Puertos del Estado and Catalan Meteorological Service.

• Animation of SST daily and night-time mean images.

• Documentation to allow installation of SAIDIN server in your site.

• Routines to analyze structures from the web.

MAMA 6th meeting, Tunis, 7-8 March 2005

Technology– Client-Server Java application (applet and servlets)

– Based on Apache Web Server and Tomcat Java Server

– All the application in one file (saidin.war) easy to deploy

– All the application configuration in one XML file

– From the client point of view 2 possibilities to run application:

• Launch the application from the web

• Launch a standalone application

MAMA 6th meeting, Tunis, 7-8 March 2005

• SST NRT AVHRR NOAA WestMed [35n-46.5n][15w-16.5e] from May 2001 till now (near-real time data) and NOAA AVHRR QuickLooks. Spatial resolution:1.1 km at nadir.

• Wind data from QuikScat/SeaWinds from WestMed [35n-46.5n][15w-16.5e] and Canary Islands:[25n-32n][21w-9w] from June 1999-September 2004 (from http://podaac.jpl.nasa.gov). Spatial resolution:0.25º, accuracy:2m/s,20º (still processing data).

• Monthly SeaWiFS chlorophyll average from WestMed [35n-46.5n][15w-16.5e] from 1997 to 2003 (still processing monthly chlorophyll from 2003 and all daily chlorophyll).

Database/Operational Products

MAMA 6th meeting, Tunis, 7-8 March 2005

Quality ControlReal time control

• Selection of passes depending on elevation angle (area coverage, enough spatial resolution)

• Few years ago, it was obtained a statistical RMS error lower than 0.6 comparing SST images with in-situ termosalinograph temperature.

Delayed mode control

• Visual inspection of data quality. Application built to help to delete images and to mark as “don't use” to create MVP images.

• Studying to perform an automatic quality control using moored buoys off the Spanish coast (Puertos del Estado) and Catalan Meteorological Service (MeteoCAT).

MAMA 6th meeting, Tunis, 7-8 March 2005

SST Data Processing

• Automated system to process every AVHRR pass over Western Mediterranean in near-real time (every hour) in order to compile a database of sea-surface temperature images at the best spatial resolution (1.1 km at nadir).

• The system has routines for automatic navigation and cloud-masking.

• After processing (split-window equation), navigated and annotated, SST images are available on WWW only 90 minutes after the start of acquisition in the worst case.

• During processing, a complete metadata file and snapshot are created. In metadata file, information like % cloud of ROI (region of interest).

MAMA 6th meeting, Tunis, 7-8 March 2005

Extracció de dadesdes de telemetría.

Calibracióradiomètrica1

Metadata6

Navegar2Treure angleselevats, núvols,reflexe del sol3

Càlcul de latemperatura4

Zona d'interès7

Georeferenciació5

Mapa deTemperatura

8

1 Radiometric calibration: Visible channels 1 i 2 to % albedo & Infrared channels 3a/b,4 i 5 to brightness T.

2 “Navigation”: Small errors on satellite internal clock and on horizon tracking require a correction on attitude and time (normally with MCC crosscorrelation algorithm a correction on roll and time is done).

3 Filtering: Satellite zenital angle > 53º --> bad data. Cloud filtering (different daytime and nightime procedure) and Sun Glint.

4 MCSST algorithm (McClain,1985) SST = A*T4 + B*(T4-T5) + C*(T4-T5)*(sec(sza)-1) + D*(sec(sza)-1) + E 5 Mercator projection with 1.1 km resolution on the square area (35n, 46.5n) x (15w, 16.5e)

6,7,8 Shown later

SST Processing Scheme

MAMA 6th meeting, Tunis, 7-8 March 2005

Sequential tests applied to all pixels.

1. if (satellite_zenith_angle > ref_angle (53º)) then bad_value

2. i (3x3) if (max(i-center) > threshold) then cloud cloud>sear

3. if (night) i (3x3) if (mean(Tb3-Tb4) < threshold) then cloud

4. if (ch2 > threshold) then cloud

5. if (Tb4 < threshold) then cloud

6. if (solar_ref_angle<min_solar_ref_angle)

then bad_value

IMPORTANT: Some clouds are not detected and appear on the image as anomalously cold areas. This is due to very dry atmosphere, low clouds, sun glint, noise in channel 3 …

Discarding pixels (mainly clouds)

MAMA 6th meeting, Tunis, 7-8 March 2005

• ICM Barcelona is a SeaWiFS Direct Readout Ground Stations. Real time decription possible for short periods under specific request

• Format conversion • Telemetry raw format n10 (encripted Data-Tools)• n10 s10 (OGP Orbview key software, every 15 days)• s10 SeaWiFS-L0 (NASA standard, SeaStarLevel0 soft)• L0 L1a (data sent to NASA, NASA software)

• Generation of quicklooks and data offered to SeaWiFS Authorized Data Users (http://seawifs.gsfc.nasa.gov/SEAWIFS/LICENSE/checklist.html).

• Management of Barcelona and R/V Hespérides data archive

• Future: automatic generation of chlorophyll a concentration maps

IMPORTANT: “At 11:59 pm tomorrow (December 23, 2004) the contract between NASA and ORBIMAGE will expire meaning that NASA will no longer have access to SeaWiFS data. All data collected between September 04, 1997 and December 23, 2004 will still be available from NASA to all authorized SeaWiFS researchers under the same terms and conditions as before.For all future access to SeaWiFS (OrbView-2) data, researchers will be required to make direct arrangements with ORBIMAGE (http://www.orbimage.com)” Gene Carl Feldman 22/12/2004

SeaWiFS Data Management

MAMA 6th meeting, Tunis, 7-8 March 2005

Go to SAIDIN demo!