Thursday, January 24, 2013

MODIS-Aqua ocean color climatologies available on Giovanni

MODIS-Aqua ocean color climatologies allow 10 years of anomaly analysis

New insights possible from higher spatial resolution and new data products


The incorporation of the recently released 10-year climatology of ocean color data from NASA's Moderate Resolution Imaging Spectroradiometer on the Aqua satellite (MODIS-Aqua) allowed the Giovanni data system to provide anomaly analysis for this important ocean data set.

The Earth Observing System Aqua satellite was launched in early 2002, and the onboard MODIS instrument began collecting data on July 4, 2002. Thus, at the end of June 2012, there were 10 years of monthly averaged MODIS data for each month of the year. The Ocean Biology Processing Group (OBPG) at Goddard Space Flight Center updates their monthly climatology files as each new month is completed. In July 2012, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) acquired these monthly climatology files to create a 10-year climatology base period for the Giovanni data system.

With the climatology files in Giovanni, researchers could then examine these climatological averages, or use the new data for anomaly analysis. The latter enhances the detection of unusual events in any long-term data set, by comparing data from a selected period to the average of the data for a much longer period (i.e., "base period"). For ocean color data in Giovanni, anomaly analysis has been available for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) for several years, but the SeaWiFS mission ended in December 2010. For MODIS-Aqua ocean color climatology data, the mission is still continuing. Furthermore, MODIS-Aqua data are available at 4 km spatial resolution, rather than the 9 km spatial resolution of SeaWiFS data.

Several new data products are available from MODIS-Aqua, including normalized fluorescence line height (nFLH), colored dissolved organic matter (CDOM) Index, absorption coefficients for dissolved and detrital matter (acdm) and phytoplankton (aph), backscattering coefficient for particulate matter (bbp), and euphotic depth (Zeu). The MODIS-Aqua climatology data also provide remote-sensing reflectance data at several more wavelengths than were available from SeaWiFS.

Giovanni's anomaly analysis capability allows users to examine monthly anomalies, and any other time period up to a year in duration. So, for example, it is possible to average data for a season (such as the spring months of March, April, and May of a particular year) and compare this three-month average to the climatological average for March through May.


Full article, with example images: < >

Monday, January 07, 2013


星洲日报, 7 Jan 2013











Sabah issues red tide alert

The Star, 7 Jan 2013

KOTA KINABALU: The deadly algae bloom, commonly known as the red tide phenomenon, will peak in the next two months statewide.

Sabah Fisheries Department director Rayner Stuel Galid said that red tide was recorded in November last year and will begin peaking between this month and February before tailing off by June.

"We are conducting daily tests and have found high toxicity in the west coast," he said, adding that anything above 400 mouse units (MU) was considered dangerous.

Galid advised people to avoid eating oysters, mussels, cockles and any type of clam though other marine products like fish, prawns and crabs were safe for consumption.

He said the red tide has been seen in waters off Papar, Kota Kinabalu and Tuaran in the west coast while they have not received any reports in the east coast.

Two boys, aged 14 and nine, died from paralytic shellfish poisoning after consuming cockles on Jan 1.

The older boy died a day after eating the shellfish while the second boy died on Friday, according to Sabah Health Department director Dr Christina Rundi in a statement.

The boys had collected the cockles from the seafront at Sepanggar about 30km from here and were said to have eaten them raw.

Galid said clams, even when cooked, are still poisonous and should be avoided during the red tide season.

Red tide is a natural phenomenon whereby algae form large colonies which produce harmful effects to marine life. The density of the algae colours the surface of the sea red.


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