South American Land Data Assimilation System (SALDAS) 5-yr retrospective atmospheric forcing datasets

The rain gauge data available in South America are very sparse and strongly biased towards more populated areas near the edge of the continent or near inland cities along the main river courses. Results of the study show the South American Land Data Assimilation System (SALDAS) dataset has a positive bias in temperature typically between 0 and 4 K. This paper describes the creation and validation of the meteorological forcing datasets used with the SALDAS System. Land surface models (LSMs) are an important component of numerical weather prediction (NWP) and global climate models, which can also be used to assess surface hydrology

Long-Range Transport of Water Channelized through the Southern Subtropical Jet

In this study, an air mass (containing a cirrus cloud) was detected by light detection and ranging (lidar) above São Paulo (Brazil) in June 2007 and tracked around the globe, thanks to Lagrangian calculations as well as ground-based and satellite observations. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data were also used to provide locations of occurrence of cirrus around the globe and extract their respective macro physical parameters (altitude and temperature). An analysis of the air mass history based on Lagrangian trajectories reveals that water coming from the Equator is channelized through the southern subtropical jet for weeks. In this case, the back-trajectories showed that the cirrus cloud detected at São Paulo was a mixture of air masses from two different locations: (1) the active convective area located around the Equator, with transport into the upper troposphere that promotes cirrus cloud formation; and (2) the South Pacific Ocean, with transport that follows the subtropical jet stream (STJ). Air masses coming from equatorial convective regions are trapped by the jet, which contributes to maintaining the lifetime of the cirrus cloud for a few days. The cloud disappears near the African continent, due to a southern excursion and warmer temperatures, then reappears and is detected again by the lidar system in São Paulo after 12 days. The observed cloud is located at a similar altitude, revealing that sedimentation is small or compensated by radiative uplift