Satellite imagery from Aqua for March 22, 2014 reveals a mega-aerosol trail, possibly two in parallel, about 400kms long over the Tasman sea to the west of the South Island. It may have been a payload from aircraft heading to/from Queenstown airport, which takes aircraft from Sydney and Melbourne. There are other aerosol trails visible in the imagery, also.
How much aerosol material could these planes be depositing in a 400km trail? Figures taken from a Geoengineering Cost Analysis by Aurora Flight Sciences, commissioned by the University of Calgary, which may bear no relation to this instance whatsoever, refers to a payload dispersal rate of 0.1 to 0.003 kg/m, with a goal of 0.03 kg/m. (See under: ‘Key assumptions,’ p. 6). Using their ideal of 0.03 kg/m, a trail about 400km long could use a staggering 12,000 kgs of material, hypothetically speaking. It is food for thought.
To see entire image, go here: http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=NewZealand.2014081.aqua.1km