Abstract:
The Atacama Desert is considered as one of the driest places on Earth. At the coastline, however, small-scale fog
oases harbor a specialized vegetation and fauna, living from moisture by fog, which is used by humans to feed
water demands of industrial projects. To date, knowledge about fog and low stratus (FLS) clouds as well as their
physical properties is limited in that only local observations or spatial products from satellites with coarse
resolutions are available generally failing to capture local patterns resulting from the complex topography.
Consequently, we provide the first climatology of FLS with 30m spatial resolution based on over 400 Landsat
scenes acquired since 1986. The new product provides valuable estimates of FLS optical and micro-physical
properties. FLS over the Pacific Ocean featured cloud optical depth values around 13.5 declining over land to
4.2. Effective radii were around 5.3 μm. Liquid water path was between 71.0 − gm 2 over the Ocean and 14.9 − gm 2
over land surfaces. The climatologies of the new Landsat product were successfully validated against those of the
MODIS cloud property product over homogeneous surfaces. Over areas with heterogeneous topographies, the
new product outperforms existing ones with coarse spatial resolutions if compared against in situ measurements.
This shows the general need for cloud products with high spatial resolutions in areas where the development of
small scale clouds is favored e.g., by a complex topography leading to systematical biases in existing retrievals.
