High Resolution Time Series Observations of Bio-Optical and Physical Variability in the Arabian Sea
Abstract
The FUOD mooring instrumented with optical and physical sensors within the upper 300 m was deployed for two 6-month periods (10/15/94 through 10/20/95) in the central Arabian Sea (15 deg 30'N, 61 deg 30'E). Both the northeast and southwest monsoons were observed. During the NE monsoon, wind speeds averaged 6 m/s and reached up to 15 m/s during the SW monsoon. Intermonsoon was characterized by weak and variable winds. Shortwave radiation and photosynthetically available radiation (PAR) displayed biannual cycles, peaking during the intermonsoon periods. The maximum winter mixed layer depth (MLD1.0 deg C at approx. 110 m) was deeper than the summer mixed layer (MLD1.0 deg C at approx. 80 m), primarily because of surface cooling and convection. A biannual cycle in chlorophyll was evident with greater values occurring during each monsoon and into the intermonsoon periods. High chlorophyll values associated with cool mesoscale features were also apparent during each monsoon. These mesoscale features and others have been documented using remotely sensed sea-surface height anomaly maps. Time series of the 1% light level depth, h1%, tracked the depth-integrated chlorophyll. In general, h1% was deeper than MLD1.0 deg C during the latter half of the spring intermonsoon (low chlorophyll periods) and shallower than h1% during the latter portions of the monsoons (high chlorophyll periods). The highest mixed layer radiant heating rates occurred during the intermonsoon periods with peak values greater than 0.15 deg C d-1 for MLD1.0 deg C. These values are consistent with those previously suggested for the central Arabian Sea. Our results indicate that biological variability is important for the seasonal variability of the upper ocean heat budget of the Arabian Sea.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 07, 1998
- Accession Number
- ADA353655
Entities
People
- Tommy D. Dickey
Organizations
- University of Southern California