Traditionally, methods used in the creation of composite temperature records have depended, implicitly or explicitly, on the assumption that the difference in temperature between two nearby sites will be a constant for any day in a given month of the year. It is demonstrated that this assumption is not necessarily valid, particularly where the sites used in the creation of a composite record differ in local topography. Two techniques are proposed to relate daily maximum and minimum temperatures at two sites during a period of overlapping records to overcome this difficulty. It is demonstrated using data from Inverell, Australia, where the difference in daily minimum temperature between two sites is significantly dependent on the temperature at one of the sites, that these techniques substantially improve the accuracy of the simulation of daily minima at one site using records from the other. The best choice of technique depends on whether the highest priority is to simulate the overall temperature record or the frequency and nature of extreme events.

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Emissions of nitric oxide and other odd nitrogen oxides (NOv) from a flooded rice field were studied after urea had been broadcast into the floodwater.The NO x flux from the fertilized area was very low (0.2 x l0 -9 g N m -2 s -I ) for the first few days after application of urea and was high (0.95 × 10 -9 g N m -2 S -1 ) in the subsequent period when significant nitrite and nitrate were present in the floodwater. At night, little if any NOx was exhaled but ambient NO2 was absorbed by the floodwater. An uptake velocity for NO2 of 3 x 10 -4 m S -1 was measured during one night. Maximum NOv losses were observed near 1300 h when temperature and solar ultraviolet light were maximum.While the amounts of nitrogen oxides emitted are of little agronomic importance (-2 x 10 -3 per cent of the fertilizer nitrogen was lost as NOv during the 10-day study period), they may well be of significance as a source for some gas reactions in the atmosphere and for the global nitrogen cycle.Of the fertilizer nitrogen applied (as urea) approximately 30% was lost to the atmosphere by NH 3 volatilization, 15% by denitrification, presumably as N 2, and the remainder, less minor losses of NO and N20, remained in the plant/soil/water system.