Data Corrections

Although quality control procedures are routinely followed during the transformation of raw data to data products disseminated through this web site or by special request from the program office, subsequent corrections are sometimes necessary. The table below provides brief descriptions of some of these changes. The absence of information regarding a given site and time period is not an indication that no change has been made. Only the most serious errors which affect substantial amounts of data are given here. Changes can potentially impact multiple data products derived from the affected data. Users concerned about the effects of changes on their studies are encouraged to download data periodically to ensure the currency of their files. Users may also contact our staff for further information.

Last Update: August 21, 2015

Data Correction Descriptions
Start Date
End Date
Problem Description
Start Date
End Date
Problem Description
California Davis(C)2001-01-012001-12-312002-08-01UV-MFRSR Irradiances corrected to compensate for faulty offset values.
Colorado Longmont(R)2003-06-232003-09-282003-10-20UV-MFRSR Angular corrections changed from YES file to CUCF file.
Colorado Longmont(R)2003-06-232003-10-012004-01-28UV-MFRSR Calibration error corrected. Problem began 2003-10-14.
New MexicoLas Cruces (C)2000-11-142000-11-272004-04-09QC flags added for VIS-MFRSR band alignment problem; data unusable.
New MexicoLas Cruces (C)2003-06-112004-05-042004-05-04Problem with VIS-MFRSR 665nm channel; data unusable during this time.
Arizona Flagstaff(C)1997-04-241997-10-092004-05-26UV-MFRSR Irradiances re-calibrated using CSU board gains.
Alaska Fairbanks(C)2004-05-212004-06-152004-06-16QC flags added for VIS-MFRSR band motion problem.
Hawaii Waimea(C)2004-01-292004-03-312004-06-22UV-MFRSR Calibration error corrected.
New MexicoLas Cruces (C)1997-05-011997-10-222004-07-01UV-MFRSR Calibration error corrected.
Maryland Greenbelt(R)2004-03-262004-05-262004-09-10New UV-MFRSR angular corrections & calibration applied.
TexasPanther Junction(C)2004-08-092004-10-272004-10-20QC flags added for sudden drop in VIS-MFRSR sensitivity.
All LocationsAll Locations2005-01-012005-01-252005-01-27Erythemal calibration problem for UVB-1 broadband data corrected.
All LocationsAll Locations2004-02-012004-02-102005-02-05Errant "bc2" QC flags pertaining to UVB-1 broadband data removed.
Colorado Nunn(C)1999-11-101999-11-112005-02-07QC flags added for ground loop problem in UVB-1 broadband data.
Maine Presque Isle(C)1998-12-111998-12-182005-02-08Data's timestep was off by 2 hours.
OklahomaBillings(C)2004-06-022005-02-172005-03-10QC flags added for sudden drop in VIS-MFRSR 610 & 665nm sensitivity.
California Holtville(C)2004-07-012005-03-312005-03-31Problem with VIS-MFRSR 665nm channel, data unusable during this time, end of affected period is uncertain.
Maryland Beltsville(C)2005-07-172005-08-102005-08-15QC flags added for VIS-MFRSR failure.
MichiganPellston(C)2004-07-142005-08-222005-08-22QC flags for sudden drop in VIS-MFRSR sensitivity added early each month for the previous month.
OntarioToronto(C)2005-11-012006-03-202006-03-20Faulty UV-MFRSR Angular corrections applied. Channel 368 was affected.
Colorado Longmont(R)2005-11-102005-12-022006-03-27Angular corrections and calibration data changed to use correct serial number data.
Louisiana Baton Rouge(C)2005-10-012006-03-312006-04-05UV-MFRSR Angular corrections changed to a newer file from CUCF
Louisiana Baton Rouge(C)2006-03-212006-03-292006-04-05Diffuser Dirty quality control flag was added to the Vis-MFRSR and UV-MFRSR data. Wavelength channel data, PAR data and UVB-1 broadband data was impacted.
Illinois Bondville(C)2006-03-072006-04-072006-04-07UV-MFRSR Angular corrections error corrected.
Florida Homestead(C)2006-01-172006-10-122006-10-12UV-MFRSR Calibration error corrected.
New YorkGeneva(C)2006-07-112006-10-122006-10-13Wrong calibration factors where applied.
MontanaPoplar(C)2006-11-092006-11-162006-11-16Broadband calibration factors not applied.
OklahomaBillings(C)2006-08-01 2006-12-07QC flags for channel failure for open, 415 and 940 added. Data should not be used.
All LocationsAll Locations2001-01-012007-07-022007-07-02Significant improvement in most Calibrated Data after 2001 was implemented on July 2, 2007. Lamp-calibrated irradiance values for the 311, 317, 325, 332, 368 channels have increased, on average, 8.8%, 22.1%, 12.1%, 11.2%, and 4.0% respectively. The 300 and 305 channels are essentially unchanged as well as the Langley calibrated data.
All LocationsAll Locations2001-01-012007-12-112007-12-11As of December 11, 2007, it was found that the Langley calibrated irradiances were in error by about +/- 3.5%. The Langley calibrations are now corrected to properly account for earth-sun distance. Previous Langley Calibrations were about 3.5% too small in January and 3.5% too large in July. Since all irradiances are calibrated at the time of the user's request, any Langley calibrated data will now reflect the proper earth-sun distance factor regardless of the date and time of the measured data.
All LocationsAll Locations1994-01-012007-12-312008-01-21The daily vnaughts for our visible wavelength range have been regenerated using a simple linear regression technique. The previous method, Dr. Joseph Michalsky's Forgan technique has been discontinued.
TexasSeguin(C)2006-08-012008-03-312008-04-30Wrong par calibration factor was applied.
North CarolinaRaleigh(C)2007-11-012008-03-312008-04-30Wrong Broadband calibration factor was applied.
MarylandQueenstown(C)2006-09-17 2008-11-04QC flags for channel failure for 415, 500, and 665 added. Data should not be used.
New YorkGeneva(C)2008-06-11 2008-11-04QC flags for channel failure for 415, 500, 610 and 940 added. Data should not be used.
ArizonaFlagstaff(C)2001-11-022008-11-212008-11-21The 311 channel was using a wrong gain factor in our calibration process. The errant gain factor used, increased the calibrated irradiance value by 1.6222.
HawaiiWaimea(C)2001-01-222001-03-272008-11-26The 311 channel is saturated. Added the quality control flag to designate the saturation. Data for this channel should not be used.
New YorkGeneva2006-07-112006-09-012009-03-16Wrong serial number used.
ColoradoSteamboat Springs2002-05-302003-03-102009-04-15UV-MFRSR Angular corrections error corrected.
OklahomaBillings2003-04-112004-11-192009-04-15UV-MFRSR Angular corrections error corrected.
CaliforniaHoltville2005-02-172009-04-152009-04-15UV-MFRSR Angular corrections error corrected.
MinnesotaGrand Rapids2003-09-112004-07-202009-04-16UV-MFRSR Angular corrections error corrected.
MainePresque Isle2004-09-152005-10-072009-04-16UV-MFRSR Angular corrections error corrected.
VermontBurlington2004-10-202009-04-162009-04-16UV-MFRSR Angular corrections error corrected.
SaskatchewanRegina2005-09-142006-07-262009-04-16UV-MFRSR Angular corrections error corrected.
All LocationsAll Locations2006-01-012009-11-012009-11-01As of November 1, 2009, lamp and Langley calibrated irradiances received a correction of about +/- 1.5% (typical) to +/-5.0% (maximum).The largest impact is on the early morning and late afternoon direct normal irradiance (low sun angles).The impact on daily sums is minimal.The magnitude of the correction is location dependent - for more information please contact the UVMRP staff.
TexasSeguin(C)2004-03-162005-06-172010-03-23The erythemal value was 0, it now has an accurate value.
ColoradoSteamboat Springs(C)2006-09-252006-09-262011-01-13Data not corrected, serial number was missing
ColoradoLamar(C)2010-08-01 2012-05-15Problem with VIS-MFRSR 500nm and 940nm channels, data unusable during this time, end of affected period is uncertain.
ArizonaFlagstaff(C)1997-04-231997-09-132014-01-27Channel failures caused by loss of sensitivity of photodiode
FloridaHomestead2009-05-122011-12-312014-12-05PAR value was found to be bad, instrument and been damaged, most likely due to lightning, data is unusable
OklahomaBillings(C)2006-08-012011-06-122015-08-21Board Gains have been changed, will only affect the lamp calibrated irradiances
LouisianaBaton Rouge(C)2015-08-062015-08-082015-08-21Board Gains have been changed, will only affect the lamp calibrated irradiances