Study of Clouds Behavior in Central Amazonia Region around Manaus City, using Caliop Information and Comparison with Measurements from Ground Based Instruments.

Abstract:

Clouds are very important in the climatic system. They can affect the atmospheric radiation budget by reflecting the incoming solar radiation and absorbing the outgoing terrestrial radiation. Semitransparent or optically thin cirrus clouds are almost all the time in the tropics region. They are composed by ice crystals. They are related with the dehydration of the upper troposphere and lower stratosphere. In despite of the importance of the clouds, the understanding of cloud characteristics and their effect on radiation is limited. Climate observations and the models outputs have been indicating cloud properties have changed and continue to change with climate warming.

Inclusion of active remote sensors as Lidar on board satellites has constituted a great advance on the atmospheric remote sensing. This type of instrument is able to retrieve the profile of clouds mainly semitransparent ones determining multiple layers of these cloud types.

We present in this paper a study of the cloud optical depth (COD) and the occurrence frequency and frequency profile of clouds in a region around Embrapa measurement site at Manaus (2.89 ºS, 59.97 ºW, 100 masl). For this purpose level 2 version 3 cloud profile data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite is used. The studied period extend from June 2006 to June 2014. The cloud optical depth frequency distributions are determined for all cloud types; resulting more frequent the semitransparent cloud types with lowest COD values. The higher COD values correcponding to the opaque cloud types. Mean monthly and hourly behaviors of the occurrence frequency of cloud types are studied. Cirrus transparent is the most frequent cloud type in all months and hours, with a maximum in September and 5 at GMT. Also, are presented and discussed the monthly and hourly frequency profile of all cloud types and the semitransparent cirrus cloud type. These results are compared with cloud optical depth measurements from the ground based Lidar and sun-photometer installed in the Embrapa experimental site.