LFTP is an enhanced sftp client that allows faster parallel down and uploads as well as a more convenient interface
LFTP Documentation can be found here 
Getting and installing
Most current Linux distributions offer lftp through their package management. However they carry mostly rather old versions which have annoying bugs.
We suggest to use at least lftp versions above 4.7.x. The LFTP web site offers source packages that enable you to compile the most recent version. Check the README and the INSTALL files in the documentation of lftp.
To install lftp using your distribution package management tool
yum install lftp sudo apt-get install lftp
Log in with your archive account
lftp -u <abc> sftp://archive-sftp.lsdf.kit.edu Password: <password>
Upload a local file (lfile) to the archive:
Upload, reverse mirror (-R), a local directory (ldir) to a remote directory (rdir) using 4 processes. Use the --continue (-c) option to allow the mirror operation to continue where it left off in case something happens (usefull if you archive thousands of files and directories).
lftp>mirror -c -R --parallel=4 ldir rdir
Download a remote directory using 4 streams for every single file. (This improves download speeds for large files):
lftp>mirror -c --use-pget-n=4 rdir ldir