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Recommendations
Surface
Fluxes
TIP presentations emphasized
the need for more systematic verification of surface flux climatologies,
and verification of surface fluxes from atmospheric and coupled ocean-atmosphere
models used in climate studies. It was therefore recommended that a few
moorings be dedicated to measurement of surface fluxes with the highest
possible accuracy. Initial mooring sites to be equipped with specialized
instrumentation were recommended along 95°W, 140°W, 165°E,
and 156°E, and one in the tropical Atlantic. Quality assurance would
need to be maintained with (i) a shore-based set of primary standards,
(ii) frequent calibration of shipboard transfer standards, and (iii) adequate
time allowances for ship/buoy comparisons on deployment and recovery.
It was recommended
that buoy flux data at these sites not be assimilated into standard operational
products; and that, to facilitate comparisons, model products be stored
at the verification buoy locations at finest temporal resolution.
Salinity Measurements
Recent evidence from
forecast models suggests that initialization errors due to lack of ocean
salinity can negatively impact the skill of El Niño SST predictions
in the tropical Pacific.
Analyses show that
lack of surface and subsurface salinity observations can sometimes lead
to errors in dynamic height that are a comparable in size to the ENSO
signal in the western Pacific. These errors affect the pressure field
and large-scale ocean circulation. Unfortunately, attempts to correct
errors in surface height using altimetry data can produce errors in the
upper ocean temperature field if salinity effects are not accounted for.
Salinity simulations in present OGCMs are unrealistic. Salinity data are
needed for understanding model shortcomings and improving model physics.
Salinity observations in key areas such as the western Pacific would be
very valuable for improved assimilation of altimetry data for ocean initialization.
Salinity is also a useful tracer of the meridional overturning circulation
in the tropical and subtropical oceans.
Existing salinity
time series show substantial high-frequency variations that potentially
can alias into low frequencies of greatest interest for climate. It was
recommended that a cost-effective strategy for increasing the salinity
data base in the tropical Pacific would be to increase the number surface
and subsurface salinity sensors on selected TAO and TRITON moorings. At
present, surface salinity is measured systematically only from ATLAS moorings
along 156°E, 165°E, and 180°E. An enhanced moored salinity
array in the tropical Pacific would contribute to an emerging salinity
monitoring effort which includes VOS/XCTDs, S-PALACE and research vessel
measurements.
Indian Ocean
Mooring Data on the GTS
Presently, India has
four moored buoys deployed in the Bay of Bengal and plans to augment these
with a further six in the Arabian Sea as part of its National Data Buoy
Programme. These buoys measure important surface oceanographic and meteorological
parameters such as wind speed and direction, air temperature, and upper
ocean temperature profiles. Since the Indian Ocean region is presently
so poorly observed, these data are potentially important both for climate
studies and for assimilation into global weather prediction models. With
proposed new experiments in the Indian Ocean such as JASMINE, ATOC, and
the proposed deployment of TRITON moorings in the Indian Ocean, moorings
of the Indian National Data Buoy Programme could represent an important
beginning of an Indian Ocean observing system.
The TAO Panel therefore
recommended that data from Indian National Data Buoy Programme should
be transmitted in real-time over the GTS to maximize their benefit for
weather and climate forecasting and analysis. A letter to Dr. E. Desa,
head of NIO, urging him to act on this recommendation, is contained in
Appendix 1. The letter was sent by Dr. Gunnar Kullenburg, Executive Secretary
of IOC, on behalf of the TAO Implementation Panel and its three sponsoring
organizations (GOOS/GCOS/CLIVAR).
Transmission
of TAO Relative Humidity Data on the GTS
Data from ATLAS moorings
of the TAO array have been transmitted on the GTS since 1987. These data
consist of surface wind speed and direction, air temperature, sea surface
temperature, and subsurface temperature profiles. Relative humidity measurements
have been collected since 1988 on the majority of TAO moorings. However,
these data have not been distributed on GTS because of early concerns
about data quality. Recent modeling studies have shown that relatively
small changes in boundary layer moisture can have a large impact on model
based flux determinations and deep convection. In order to improve the
model boundary layer analyses in the operational atmospheric models, it
is recommended that the humidity measurements from the TAO moorings be
added to the surface messages that are distributed on GTS. Present accuracy
for humidity measurements from the TAO moorings are estimated at 4% or
better, which is well within the range considered useful for present modeling
efforts.
Data Buoy Cooperation
Panel Action Group
Motivated by a history
of effective informal collaboration between the TAO Implementation Panel
(TIP) and the WMO/IOC Data Buoy Cooperation Panel (DBCP), the suggestion
was made at TIP-6 that the TIP become an Action Group of the DBCP. The
benefits of becoming an Action Group are immediate and include, among
other things, direct participation in a most effective international mechanism
for coordinating the implementation of the global array of research and
operational ocean buoy programs and for speaking with a united voice on
real-time data transmission and usage issues affecting all programs. Membership
also permits full access to the resources of the DBCP Technical Coordinator,
Mr. Etienne Charpentier, to assist in solving real-time data retrieval
and dissemination problems. Although the TIP has functioned well as a
virtual member of the DBCP, a formal association between the two bodies
would enhance the effectiveness of the TIP in the international operational
buoy community. It is therefore recommended that Dr. McPhaden send a letter
to the DBCP Chairman requesting formal recognition of the TIP as an Action
Group of the DBCP*.
*Editor's note: A
letter of request was sent to the DBCP chairman Mr. Graeme Brough by Dr.
McPhaden on 5 February 1998. Mr. Brough responded on 25 February 1998
that TAO would be recognized as an Action Group of the DBCP.
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