Campbell Scientific LI200X LI200X-L LI-COR Silicon Pyranometer - Page 13

13: Real Time (P77) 1: 1220 Year,Day,Hour/Minute (midnight = 2400) 14: Resolution (P78) 1: 1 High Resolution 15: Totalize (P72) 1: 1 Reps 2: 4 Loc [ SlrMJ ] 16: Resolution (P78) 1: 0 Low Resolution LI200X Pyranometer 4.2 Total Solar Radiation If the solar radiation is totalized in units of kJ m-2, there is a possibility of overranging the output limits. For CRBasic dataloggers, you can avoid this by using the IEEE4 or long data format. The largest number that an Edlog datalogger can output to final storage is 6999 in low resolution and 99999 in high resolution. For Edlog dataloggers, if you assume that the daily total flux density is desired in kJ m-2 and assume an irradiance of 0.5 kW m-2, the maximum low resolution output limit will be exceeded in just under four hours. This value was found by taking the maximum flux density the datalogger can record in low resolution and dividing by the total hourly flux density. 6999 kJ m −2 ( )( ) 3.9 hr = 0.5 kJ m −2s −1 3600 s hr −1 (1) To circumvent this limitation for Edlog dataloggers, record an average flux (see Example 2). Then, during post processing, multiply the average flux by the number of seconds in the output interval to arrive at a output interval flux density. Sum the output interval totals over a day to find a daily total flux density. Another alternative for Edlog dataloggers is to record total flux using the high resolution format (Instruction 78, see Datalogger manuals for details). The disadvantage of the high resolution format is that it requires four bytes of memory per data point, consuming twice as much memory as low resolution. 5. Maintenance On a monthly basis the level of the pyranometer should be checked. Any dust or debris on the sensor head should be removed. The debris can be removed with a blast of compressed air or with a soft bristle, camel hair brush. Check that the drain hole next to the surface of the sensor is free of debris. 9