92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012: 2:45 PM
Persistent Cloudiness Features Associated with Ocean Bottom Topography
Room 256 (New Orleans Convention Center )
Michael W. Douglas, NOAA/NSSL, Norman, OK; and A. Dominguez

To complement ongoing mesoscale cloud climatology work we have recently used 5 km NASA MODIS true color “browse” mosaics to generate global cloudiness fields for an 8-year period. Despite clear limitations of these browse mosaics the mean cloud fields generated from them agree closely with our 250m pixel MODIS-based climatologies over land areas where we had previously focused our attention. The 5 km mean cloudiness fields show unexpectedly detailed spatial variations over the southern oceans - and also over smaller regions (Kuroshio extension and Grand Banks) of the northern oceans. Averaging the cloudiness data by month or by year shows that there is essentially no seasonal or interannual variation in the location of these features – they are geographically fixed. The locations of many of these cloudiness features coincide with persistent sea surface temperature fronts reported in the literature – fronts whose positions have been linked to the underlying bottom topography. Displaying the mean cloudiness fields in Google Earth confirms the close relationship between the bottom topography and many of the cloud patterns. Thus the detailed spatial variations of the mean cloudiness over the southern oceans and parts of the north Atlantic and Pacific are related directly to the interaction of deep oceanic currents and the bottom topography. Our work also highlights the value of browse products, despite their limitations, that are easily available to the scientific community.

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