Cooling and heating due to latent and sensible heat over the Yucatan continental shelf

J. HERNÁNDEZ TÉLLEZ, J. ALDECO RAMÍREZ, DAVID ALBERTO SALAS DE LEÓN

Abstract

From meteorological data and sea surface temperatures taken during the oceanographic cruises PLAYUC (January 6 to 17, 1990) and YUCPLA (May 25 to June 4, 1990), conducted over the Yucatan Continental Shelf, the cooling and heating areas produced by the fluxes of latent (Qe) and sensible heat (Qt) were determined. The computation was done using the bulk aerodynamic equations. During PLAYUC, the line of SST - Ta = 0 (sea surface temperature minus air temperature) divided roughly the study area into two regions (east and west). This was caused by two moderated northers. At the west side the difference SST - Ta was between 1 and 4ºC, and at the lower east side the difference was between -1 to -3ºC. The values of Qe and Qt for the cooling area at the west were from 160 to 260 W/m2 and from 10 to 60 W/m2 respectively. At the east portion the diurnal contrast of Qewas observed at three small areas. North of Cabo Catoche a fog was present over a weak upwelling area, reducing the cooling rate due to Qe from 30 to below 10 W/m3 and the heating due to Qt to values around -5 to -6 W/m2. The average values during PLAYUC for Qe and Qtover the shelf were 140.92 and 14.88 W/m2, respectively. During YUCPLA, influence of moist and warm air from the East was observed. Two lines of SST - Ta = 0 divided the study area diagonally in two portions, northwest and southeast. The difference SST - Ta for the northwest portion was from -1 to 0ºC and for the southeast from -4 to 0ºC. During this second cruise the cooling was less intense and with weaker spatial contrast. At the NW portion two intrusions of Qe were observed, one toward the coast and another going offshore. At the SE portion a north-to-south tongue was observed. Similar to what was the case during PLAYUC, the upwelling and fog area promoted a heating due to condensation (Qe < 0). At the NW portion three well delineated regions of heating and cooling were observed, showing the diurnal variations. The average values during this cruise for Qe and Qt were 66.63 and 0.36 W/m2, respectively.

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