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%                    C M / I N T R O . T E X 
%                    doc: Fri Mar  3 12:47:08 2000
%                    dlm: Wed Jun  7 22:35:12 2000
%                    (c) 2000 A.M. Thurnherr
%                    uE-Info: 46 20 NIL 0 0 72 3 2 4 ofnI
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In this chapter the data from 21 moored current meters
\rsec{CM-methods} are analyzed and interpreted. The main goal is to
quantify the temporal variability of the transport across \RS which is
required to assess the uncertainties associated with along-valley flux
estimates of hydrothermal tracers (e.g.\ \rchapNP{HFLUX}).
Additionally, the analysis yields estimates for the temperature
variance which can be compared to the hydrographic surveys \rchap{HYD},
and allows the particle plume dispersal to be interpreted in the
context of the background flow field \rchap{plume}.

In \rsecNP{CM-event} it is shown that the low-frequency (weeks to
months) temperature fluctuations are dominated by a transient warming
event lasting approximately 4 months with a strong signature in the \RS
overflow velocities. Simple spectral techniques are applied to
investigate the contributions from different frequency bands to the
overall flow energy \rsec{CM-energy}. The current meter records show
large temporal and spatial heterogeneity which make detailed
interpretation difficult. Common properties include dominance of the
clockwise-polarized rotary component decreasing with increasing depth,
as well as the low frequencies and the semi-diurnal tidal band
dominating the flow energy. (Where strong flow had been observed during
the 1997 LADCP survey \rsec{LADCP} the low-frequency component
dominated throughout the year.) The transient warming event had a
complex effect on the patterns of energy partition at all depths within
the rift valley.

The temperature variability on time scales less than one week is
analyzed in \rsecNP{CM-tempvar}. The results indicate that the RMS
amplitudes remained approximately uniform throughout the year with the
variance decreasing with depth. In the vicinity of \RR the variability
is higher than elsewhere and consistent in magnitude with the
observations of the hydrographic surveys \rchap{HYD}. The strong return
flow at \m{1800} across \RS observed at the end of the mooring
deployment coincides with a factor 2 decrease in the semi-diurnal
temperature excursions of the affected instruments.

In \rsecNP{CM-asflow} the along-segment flow and the transport across
\RS are investigated. Somewhat surprisingly, the volume flux remained
approximately constant during the entire year, in spite of the warming
event. The chapter concludes with a discussion in \rsecNP{CM-discu}.

