id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
124	Lack of precison in some netCDF parameters	Dave Offiler	Dave Offiler	"Axel reports that RoC and Impact Parameters in the ROPP netCDF files are saved at low-level in single-precsion (SP) despite being double-precison (DP) in the ROPP structures. With typical values of these parameters (64 megametres), this limits precision to no better than 1m (BUFR, at least theoretically, supports 0.1m). This limitation in precision is causing some subtle problems in the interpolation methods of the ROPP thinner where IPs are offset by the RoC.

Axel's recommended solution is to change the type definitions for RoC and IPs from SP to DP in ropp_io_write_ncdf_def.f90. This change is allegedly transparent to the user as the low-level netCDF interface should handle the type conversion on-the-fly for read & write.

He confirms that he can correctly read an old ROPP netCDF file (one with RoC saved in SP) with re-compiled ROPP reader code (with RoC defined in DP).

This change needs to be implemented in our local code and tested more throughly."	defect	closed	normal	1.1	ropp_io	1.0	fixed	Precision, RoC, Impact Parameter	Michael Rennie Huw Lewis