Fig. 1
The location of the Gulf of Aden.
Table 1. Reanalysis variables and variables calculated from reanalysis variables that were used in this paper
Reanalysis variablesAir temperature (TA)2 m°CSea-surface temperature (SST)Sea surface°CSpecific humidity (SH)2 mg/kgu component of wind10 mm/sv component of wind10 mm/sSea level pressure (SLP)Sea surfacehPaCalculated variablesWind speed (WS)10 mm/sAir-sea temperature difference (ASTD)2 m°CRelative humidity (RH)2 m%
Fig. 2
Monthly means of air–sea temperature difference in the Gulf of Aden (units: °C).
Fig. 3
Comparison of the temperature stability function, Ψ h , versus the atmospheric conditions, functions versus z/Z, for the three different NPS models.
Fig. 4
Comparison of the wind stability function, Ψ m , versus the atmospheric conditions, z/Z, for the three different NPS models.
Fig. 5
Modified refractivity profiles computed by the different NPS models. The dot in each line indicates the location of the EDH.
Fig. 6
Comparisons of the Arabian Sea experiment and NCEP CFSR data set. (a) Air temperature (AT), sea-surface temperature (SST), relative humidity (RH) and wind speed (WS) data from 16 October 1994 to 20 October 1995. (b) Monthly mean and standard deviations (SD) of AT, SST, RH and WS. (c) Monthly mean and SD of the evaporation duct height (EDH) calculated from the buoy data and NCEP CFSR data.
Fig. 7
Spatial and temporal variation of evaporation duct height in the Gulf of Aden (units: m).
Fig. 8
Seasonal variation in surface wind. Arrows represent the wind direction. (a) North-east monsoon. (b) Spring intermonsoon. (c) South-west monsoon. (d) Fall intermonsoon.
Fig. 9
Seasonal variation in air temperature (units: °C). (a) North-east monsoon. (b) Spring intermonsoon. (c) South-west monsoon. (d) Fall intermonsoon.
Fig. 10
Seasonal variation in relative humidity (units:%). (a) North-east monsoon. (b) Spring intermonsoon. (c) South-west monsoon. (d) Fall intermonsoon.
Fig. 11
Seasonal variation of the sea-surface temperature (SST) (units: °C). (a) North-east monsoon. (b) Spring intermonsoon. (c) South-west monsoon. (d) Fall intermonsoon.
Fig. 12
The change in sea-surface temperature (SST) during the south-west monsoon (units: °C).
Fig. 13
Sensitivity of evaporation duct height to meteorological parameters.
Fig. 14
Real-time AIS map of ships in the Gulf of Aden. The green points represent the real-time positions of the ships. The red line represents the approximate marine route for ships crossing the Gulf of Aden.
Fig. 15
(a) Evaporation duct height (EDH) distribution along the marine route in July in the Gulf of Aden. (b) The EDH cliff on the marine route.
Fig. 16
Ducting effects on the detection ability of marine radar. (a) Marine radar is located in the duct layer. (b) Marine radar is located out of the duct layer.
Fig. 17
Ray trace of the radar waves in the evaporation duct when ships sail in different directions to cross the evaporation duct height (EDH) cliff: (a) from high EDH region to low EDH region, and (b) from low EDH region to high EDH region.