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                              Data Description

    Time series data of NOAA Coral Reef Watch operational near-real-time 
       twice-weekly satellite coral bleaching monitoring products for
                            selected reef sites
  (http://coralreefwatch.noaa.gov/satellite/current/sst_series_24reefs.html)

                               (11 June 2007)
==============================================================================

Currently, the web-accessible site-specific near-real-time time series data 
that are extracted from NOAA Coral Reef Watch's operational near-real-time 
twice-weekly satellite coral bleaching monitoring products are available only 
for selected reef sites (virtual stations).  See the list of all the available 
sites at http://coralreefwatch.noaa.gov/satellite/current/sst_series_24reefs.html. 
These data are provided for the period covering December 2000 to the present.  

The bleaching monitoring products are derived from satellite nighttime sea 
surface temperatures (SSTs) observed by the Advanced Very High Resolution 
Radiometer (AVHRR) carried on NOAA's Polar Orbiting Environmental Satellites 
(POES).  The details of these monitoring products are available at our website, 
http://coralreefwatch.noaa.gov/satellite/index.html.

Along with our operational monitoring products, the time series data are 
currently updated twice-weekly on Monday and Thursday mornings (U.S. Eastern
Time).  Prior to May 3 2007, the data were updated on Tuesday and Saturday
mornings (U.S. Eastern Time).  This change is identifiable in the date of the 
time series data records.  The Monday update provides four-day composite data 
of the preceding Thursday, Friday, Saturday, and Sunday; the Thursday update 
provides three-day composite data of the preceding Monday, Tuesday, and 
Wednesday.  Prior to May 3 2007, updates on Tuesdays and Saturdays provided 
3-day composite data of preceding Saturday, Sunday, and Monday and 4-day 
composite data of preceding Tuesday, Wednesday, Thursday and Friday, 
respectively.

The data file is in ASCII (text) format.  The first record of each data file 
is the header providing titles for each field in the subsequent data records. 
There are 15 fields in each record (row) and they are described in detail 
below.  Each row provides data for one twice-weekly composite.


BYYY, BM, BD, BH:

These are year, month, day, and hour (GMT time), respectively, giving the 
beginning time of the composite time period of a record.  During a successful 
twice-weekly data update, this time is identical to the EYYY, EM, ED, and EH 
(See below) of the previous record. 

The first observation included in the current composite does not necessarily 
occur within seconds or minutes after the beginning time.  We use only the 
nighttime SST observations for coral bleaching monitoring.  At the official 
"begin" time (BYYY, BM, BD, BH), the satellite may be at the border of an 
orbit transiting from night time to day time.  If so, the last observations 
in the nighttime portion of this orbit go into the previous composite.  The
POES orbit period, which is the time it takes to complete one orbit of the
Earth, is approximately 100+ minutes, so the next nighttime observation may 
not start until one to two hours later.

In the time series, a gap, if any, between BYYY, BM, BD, BH of a composite 
record and EYYY, EM, ED, EH of the previous record, indicates that data 
loss might have occurred.


EYYY, EM, ED, EH: 

These are year, month, day, and hour (GMT time), respectively, giving the 
time of the last (i.e., newest) nighttime SST observation that is available 
and used in producing a twice-weekly SST composite at the time of the 
scheduled near-real-time data update.

In the time series, if the ending time (EYYY, EM, ED, EH) of a composite is 
much later than the usual ending time described above or out of the pattern 
of most of the ending times in the time series, technical glitch might have 
occurred at the time of data processing; data processing was resumed at a 
later time and included any additional observations available at the time.

The beginning time (BYYY, BM, BD, BH) and ending time (EYYY, EM, ED, EH) 
together define the time period for a composite.


SST: 

Twice-weekly sea surface temperature (SST) composite value in the units of 
degrees Celsius.  Additional information on the SST product can be found at 
http://coralreefwatch.noaa.gov/satellite/current/key_sst_50km_field.html.


SSTANOM: 

SST anomaly value in the units of degrees Celsius.  The information on the 
SST anomaly product can be found at 
http://www.osdpd.noaa.gov/PSB/EPS/SST/climo.html.


HOTSPOT: 

Bleaching HotSpot value in the units of degrees Celsius. The information 
on the bleaching HotSpot product can be found at 
http://www.osdpd.noaa.gov/PSB/EPS/SST/climohot.html.


DHW: 

Bleaching Degree Heating Weeks (DHW) value in the units of degree-weeks. The 
information on the DHW product can be found at 
http://www.osdpd.noaa.gov/PSB/EPS/SST/dhw_retro.html.


Lat and Lon:

Latitude and longitude of the center of the pixel in the units of degrees-
north and degrees-east, respectively.


Reef_Name: 

The name of the reef site (virtual station).


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NOAA Coral Reef Watch (coralreefwatch.noaa.gov)