Building large cloud based systems requires good engineering. Especially if this involves the BigData Processing and Real Time Analysis. This is also a fast moving technology space. An Architect in this domain should see above and beyond the business requirements anticipating future changes. He should be well versed with the current solution design and keep track of the latest trends in the technology and tools used in this space...
A Data Architect would be required to design products which requires careful integration of these skill sets.