ADJUSTMENTS TO THE METEOROLOGICAL DATA

BEACON VALLEY

On February 12, 2003, wind direction (WDIR) values were corrected by Thomas Nylen for a systematic error in the measurement created by improper wiring. The wind sensor still worked, but the values were systematically off. The wind direction is off by 180 degrees and mirrored around the north-south axis. For example a wind direction of 160 degrees was corrected by adding 180 degrees to it (340 or -20) and takING the mirror value of that, i.e. 20 degrees.

On June 4, 2004, all of the relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The polynomials used for the correction is based on Lowe (1977). The original RH value is multiplied by the saturation vapor pressure over water and divided by the the saturation vapor pressure over ice

Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

LAKE BONNEY

On August 24, 1999, the data manager did some fine-tuning of the data, as requested by Thomas Nylen. This included:

Placement of flags for WDir and WDirStD between Jan 6, 1998 @ 17:15 and Jan 15, 1998 @ 9:00. It was assumed the data was deleted because the wind direction values = 0. This needed to be indicated in the notes portion of the file.
Deletion of SoilT5cm, SoilT10cm, SwRadIn, SwRadOut, PAR, LwRadIn and LwRadOut2 values on 1/15/98 @ 9:15. They all appeared suspect are regarded as bad data.
Deletion of precipitation values between 1/15/98 @ 10:15 and 1/15/98 @ 10:45. The values were zero & are regarded as bad data.
Removal and flagging of the WDirStd data from Nov 12, 1994 @ 17:20 to Jan 20, 1995 @ 10:20.
Addition of precipitation values between Dec 5, 1994 @ 11:20 Jan 20, 1995 @ 10:20. At the request of Thomas Nylen, the first value for precipitation in this group was subjectively voided, and the 3 values right after this file were deleted (01/20/1995 10:20:00 AM to 11:00 AM).
Addition of WSpd, WSpdMax and WSpdMin values between Dec 5, 1994 @ 11:20 Jan 20, 1995 @ 10:20. In addition, WDir and WDirStd on 12/26/1994 4:00:00 was voided because the wind speed = 0.
Addition of records taken between Nov 9, 1995 @ 19:20 and Nov 22, 1995 @ 16:20. These records were not among the file provided on the web to that point.

In May 2000, the 1999-2000 data was posted. In the process, Denise Steigerwald changed the layout of the files so that they were sorted by category (air temperatures, humidity, radiation, wind etc.) rather than by year. Files containing monthly and daily averages were generated and minor adjustments were made to the metadata.

On May 16, 2000, relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The formula used for the correction was:

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

In June 2000, summary files were added to the web containing daily and monthly statistics. These were generated by creating "views" of daily and monthly means, minimums, maximums and counts of the records represented in the Oracle database's meteorology tables.

In May 2003, PAR values between 11/20/01 10:30 AM and 1/24/02 11:45 AM were changed because the wrong multiplier was used the first time it was processed. The values were divided by 1.37283 (old multiplier) and multiplied by 1.64249 (correct multiplier).

In Apr 2004, LwRadIn data between 11/17/2000 @ 1130 am and 01/09/2002 @ 08:45 am were delete and flagged as "LwRadIn value recorded by instrument but known to be bad data". The sensor values were considerably lower than the tempeature corrected LwRadIn2 value. The battery in the Eppley Pyrgeometer was probably left in, which affects the output voltage.

On June 4, 2004, the relative humidity (RH) values after January 15, 2000 @ 1300 were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The polynomials used for the correction is based on Lowe (1977). The original RH value is multiplied by the saturation vapor pressure over water and divided by the the saturation vapor pressure over ice

Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

LAKE BROWNWORTH

The first 96 records found in the 978/brh/brh97f01 file contained the same dates/times as the latter portion of the 967/brh/brh96702 file (overlap of records in the 1996/97 & 1997/98 files). Although the values in these files did not contain exact matches, a choice had to be made on which records to use. The data manager subjectively decided to use the 1996/97 records. This explains why the first record number (fline#) from the 978/brh/brh97f01 file is '978/brh/brh97f01.96', rather than 978/brh/brh97f01.0. If you have any questions, please contact the data manager.

On August 17, 1999, the data manager added the 1998-1999 data to this dataset. In the process, she did some fine-tuning of the data, which included:

removal of the relative humidity data from November 1995 through April 1996, as requested by Peter Doran. The values during this period were unquestionably low, so it was recommended that the values be marked as bad and not included in the data files.
making the file layout consistent from year to year. This results in many null values being present for periods when certain values were not collected. However, it simplifies combining data from different years.
making corrections so that the files containing data for a given year started on January 1 at 0:00 and ended on December 31 at 23:45. Up to this point, records for January 1 between 0:00 and 12:45 were appearing in the previous year's file.
Fine-tuning of the comments fields so they were more concise and/or explanatory. For example, radiation comments were updated from "SwRadIn flagged with an 'S'" to "Negative value for SwRadIn zeroed out". The 'WDir Comments' field was renamed to 'Wind Comments'.

With the exception of removal of the relative humidity values described above, data values were not changed.

On August 27, more fine-tuning of the data occurred. This included:

addition of NetRad from Nov 24, 1995 @ 16:45 to Jan 23, 1996 @ 11:00.
addition of SwRadOut and PAR from Nov 13, 1996 @ 15:15 to Jan 25, 1997 @ 10:15.

On July 3, 2001, Thomas Nylen adjusted the data. This included:

Added 37 degrees (clockwise) to WDir results between 11/20/1995 16:00 and 11/27/1998 11:15
Subjectively voided WDir and WDirStD between 3/1/1996 00:15: and 04/19/96 23:30

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

In May 2003, SwRadIn values between 12/30/1994 10:00:00 PM and 4/19/1996 11:30:00 PM were changed because it was determined the wrong multiplier was used. The values were corrected by dividing by 88.4 (mAmps m^-2) and multiplying by 113.12 (W m^-2).

On June 4, 2004, the relative humidity (RH) values after January 26, 2000 @ 1545 were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The polynomials used for the correction is based on Lowe (1977). The original RH value is multiplied by the saturation vapor pressure over water and divided by the the saturation vapor pressure over ice

Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

CANADA GLACIER

Files were submitted by Karen Lewis to the McMurdo LTER data manager in October, 1997 and March, 1999. In order to get the dates and times in the proper format, Denise Steigerwald changed any times marked as 24:00 to 0:00, and added 1 to the corresponding julian date. Julian dates and times were then converted to a format with mm/dd/yy hh24:mm in order to make this file more compatible with other McMurdo LTER files. Variables were renamed to match with corresponding measurements at other meteorology stations. A column was also added for location code in order to identify the station of these measurements. Updates were done using Microsoft Excel and Access software. Comma delimited ascii files were then generated to make the data files available on the web page.

In June, 1999, it was determined that the transformations used to get records from level 0 to level 1 did not occur for the data sets submitted by Karen Lewis. Denise Steigerwald, the data manager, therefore replaced what she could with data sets that originated at the Desert Research Institute and had undergone these transformations. This included records between November 10, 1995 and August 21, 1996. The remaining records were downloaded by Thomas Nylen to allow him to get the records to level 1. On September 29, 1999, the level 1 records on the web replaced the level 0 records.

On May 17, 2000, relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The formula used for the correction was:

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

On June 4, 2004, the relative humidity (RH) values after January 16, 2000 @ 1600 were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The polynomials used for the correction is based on Lowe (1977). The original RH value is multiplied by the saturation vapor pressure over water and divided by the the saturation vapor pressure over ice

Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

COMMONWEALTH GLACIER

While processing the 1997-98 files, Peter Doran identified an error in the LWRadIn values for the Commonwealth station in 1996-97's data from Julian day 319 of 1996 at 15:45 local time to Julian day 27 of 1997 at 9:00 local time. To correct the LWRadIn values during this period the values needed to be multiplied by 0.800514. The data manager at INSTAAR did this & provided updated versions of the data sets in May, 1999.

On August 18, 1999, the data manager added the 1998-1999 data to this dataset. In the process, she did some fine-tuning of the data, which included:

removal of the relative humidity values from November 14, 1996 through December 4, 1996, as requested by Peter Doran. Since the temperatures were bad during this period, and relative humidity is based on temperature, the RH data needed to be voided as well. They had been marked as subjectively voided in the comments field, but needed the values removed from the RH field.
removal of records on 5/20/1994 2:00:00 and 5/20/1994 11:00:00. These contained incorrect data.
removal of SwRadOut values on 12/25/1994 13:00:00, 12/25/1994 13:20:00, and 12/25/1994 13:40:00. These records had very high SwRadOut and no SwRadIn values, so Peter Doran determined that it was best to delete the 3 SwRadOut values.
removal of ThmIR values of -999.99 from the 1994 data. This was a level 0 campbell code and should not have been in the level 1 data set.
making the file layout consistent from year to year. This results in many null values being present for periods when certain values were not collected. However, it simplifies combining data from different years.
making corrections so that the files containing data for a given year started on January 1 at 0:00 and ended on December 31 at 23:45. Up to this point, records for January 1 between 0:00 and 12:45 were appearing in the previous year's file.

On August 31, 1999, at the request of Thomas Nylen, more updates were made including:

removal of wind direction and wind direction standard deviation values for records where wind speed = 0;
removal of all commas from the comments fields, since commas cause spreadsheet software packages to add additional columns;
addition of relative humidity values from Jan 23, 1995 @ 14:20 to Nov 27, 1995 @ 10:20. The task sheet gives no explanation nor data to indicate why it was omitted. The data looks good when plotted, so it was decided to include it.
addition of ice temperature values (at 20 cm & 1 m depths) from Nov 27, 1995 @ 12:15 to Jan 24, 1996 @ 10:30. Up to this point, the values were omitted from the data column and flagged. Looking at the values before and after this time period, the ice temperature data was also flagged, but the values were left in the data column. The data appears to be continous across each of these time periods, and it was not logical why one period was omitted, but the before and after values were not. The data between Nov 27, 1995 @ 12:15 and Jan 24, 1996 @ 10:30 was therefore placed back, though flagged.
addition of wind direction values from Dec 19, 1995 @ 15:15 to Jan 24, 1996 @ 10:15. The task list stated that the arm was rotated 13 degrees on Jan 24. According to Peter Doran, the data should be left, but flagged.
removal of ThmIR values between 12/19/1995 11:15 and 12/19/1995 13:00.
updating of SwRadIn and SwRadOut values between Nov 25, 1997 @ 13:00 and Jan 16, 1998 @ 9:45. The wrong multiplier was used for SwRadIn and SwRadOut between Nov 25, 1997 @ 13:00 and Jan 16, 1998 @ 9:45. Two flags for SwRadOut, 01/02/1998 11:30 and 01/02/1998 12:00 were removed with the recalculated values.
removal of LwRadIn2 and LwRadOut2 values between Jan 1, 1999 and Jan 22, 1999 @ 10:15. These values were bad for the whole dataset.
removal of 1998-99 IceT20cm values above 0 (above the range limit).

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

On June 6, 2000, the dataset showing longwave radiation measurements was updated. Thomas Nylen had gone through values recorded before January 22, 1999 and made some changes to these values and their corresponding flags (comments). Many of the fields were originally left blank but have now been assigned an appropriate number.

In April 2003, the LwRadOut2 data were adjusted between 01/20/1999 12:45 PM and 01/23/2003 04:15 PM to account for erroneous dome thermister measurements made by the Eppley precision spectral pyranometer. The problem was identified by Eppley when recalibrating the instrument. The dome and case temperatures should be about the same, especially in the winter. The voltage measured by the dome thermister was consistently 9% higher than the case thermister. To correct the problem the dome thermister were divided by 1.09 and the LwRadOut2 values were calculated again using the methods outlined in Procedures for Correcting Eppley Pyrgeometer Data. The revised values were on average 11.2% higher than the previous calculated values.

EXPLORER'S COVE

On September 6, 1999, the data manager added the 1998-1999 data to this dataset. In the process, she did some fine-tuning of the data, which included:

Removal and flagging of precipitation values between Nov 21, 1997 @ 11:00 and Jan 13, 1998 @ 9:30. This was done at the request of Thomas Nylen.

On May 24, 2000, relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The formula used for the correction was:

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

LAKE FRYXELL

On August 16, 1999, the data manager added the 1998-1999 data to this dataset. In the process, she did some fine-tuning of the data, which included:

Removal and flagging of WDirStd values between Nov 28, 1994 @ 15:40 and Nov 30, 1994 @ 14:00. The task sheet in frl94501.dat and frl94502.dat both indicated the WDirStD should be flagged, but only the data covering frl94502.dat had been flagged.
Removal of all RichNo and RichNo Comments from 11/21/1995 12:40:00 to 1/24/1996 12:15:00, since data was not collected after 11/21/95.
addition of PAR values for the entire portion of 1997. This data was accidently dropped and needed to be added back.
removal of all commas from the comments fields, since commas cause spreadsheet software packages to add additional columns.

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

On May 6, 2003, radiation values were omitted between June 25, 2001 @ 0230 to Nov 27, 2001 because station was blown over.

LAKE HOARE

On September 2, 1999, at the request of Thomas Nylen, the data manager did some fine-tuning of the data. This included:

Addition of AirTdel3m1 values between Dec 18, 1993 @ 20:30 and Jan 22, 1995 @ 23:40. Although these values were listed as good in the task list, they had accidently been removed from the files.
Addition of precipitation values from Nov 19, 1994 @ 00:20 to Jan 22, 1995 @ 23:40. The task list indicated the data was good, but it had been removed from the files.
Addition of PresSta values from Nov 18, 1994 @ 23:40 to Jan 22, 1995 @ 23:40. The task list indicated the data was good, but it had been removed from the files.
Addition of WSpdMax and WSpdMin values from Dec 28, 1994 @ 22:00 to Jan 22, 1995 @ 23:40. The task list indicated the data was good, but it had been removed from the files.
Removal and flagging of WDirStD and WSpd values between Dec 2, 1994 @ 21:00 and Dec 28, 1994 @ 11:40. The values had been flagged in the task list. Since data collected prior to this period contained the same flags and were subjectively voided, a similar approach seemed appropriate for these records.

On May 30, 2000, relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The formula used for the correction was:

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

In May 2003, incoming and outgoing shortwave radiation between December 18, 1993 @ 1930 and Jan 16, 1994 @ 2300 were flagged as questionable. Often during this period there are maximum and minimum threshold values that the sensors reach and do not fall above or below.

HOWARD GLACIER

On September 3, 1999, at the request of Thomas Nylen, the data manager did some fine-tuning of the data. This included:

Deletion of flags for ice temperature measurements from Nov 20, 1993 @ 16:30 to Dec 24, 1993 @ 14:30. Instruments were not installed during this time;
Removal and flagging of WDir values for measurements taken between Nov 23, 1994 @ 10:20 and Jan 23, 1995 @ 13:20 where WSpd = 0. Since the wind speed values during this time were flagged as bad, the original database query probably did not flag the WDir data when WSpd =0.

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

On May 7, 2003, SwRadIn and SwRadOut values between 11/20/1993 4:30:00 PM and 11/23/1994 8:00:00 AM flagged as questionable because the values are significantly lower than the other stations during the same time period. It appears the pyranometers were either tilted or installed improperly. Also SwRadIn and SwRadOut values between 11/25/1997 @ 1445 and 01/10/1998 1430 because the wrong multiplier was used. The SwRadIn values were divided by 109.29 and multiplied by 115.61 and the SwRadOut were divided by 108.7 and multiplied by 116.41.

On June 29, 2004, wind direction between 11/20/1993 16:30 to 11/27/1995 15:00 was flagged because the data is about +25 degrees off from the true direction. This was determined by comparing the daily wind direciton over the entire 10 years of record. Additionally, between 11/27/1995 15:30 to 11/25/1997 13:30, the wind direction data was flagged because it is about -10 degrees off from the true direction.

TAYLOR GLACIER

On September 8, 1999, at the request of Thomas Nylen, the data manager did some fine-tuning of the data. This included:

Removal and flagging of WDirStD values between Nov 21, 1994 @ 15:20 and Jan 23, 1995 @ 9:20. Wind speed had already been flagged for this period, and it was determined that WDirStD values needed a similar approach.
Revision of LwRadIn values between Dec 19, 1995 @ 19:15 and Jan 25, 1996 @ 9:30. The initial LwRadIn values were zero, or close to zero. During the same period, LwRadIn2 had values consistent with the operation of the instrument. Since LwRadIn2 modifies the LwRadIn values, it was concluded that the values for LwRadIn must have been lost. Thomas therefore resubmitted the correct values to use.

On May 31, 2000, relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The formula used for the correction was:

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

On June 29, 2004, Thomas Nylen flagged the incoming and outgoing shortwave radiation data between 11/21/1994 @ 1520 to 12/01/1995 @ 0945 as questionable because the values are significantly higher than L. Bonney during the time period. During this time period, two Licor pyranometers were used, but were wired similar to the Eppley Pyranometers and used the same lines in the program. It is suspected that the incorrect wiring and/or program caused the higher output. After two Eppley Pyranometers were installed on the station on December 1, 1995 @ 1045, the values matched the measurements made at Lake Bonney.

LAKE VANDA

On September 9, 1999, the data manager added the 1998-1999 data to this dataset. In the process, at the request of Thomas Nylen, she did some fine-tuning of the data. Revisions included:

Removal and flagging of WDir and WDirStd values on Nov 25, 1994 @ 9:20. Since wind speed was zero (0), it made no sense to have values for wind direction.
Addition of PAR values between Dec 30, 1994 @ 17:00 and Jan 20, 1995 @ 15:00.

On June 1, 2000, the 1999-2000 data was posted. In the process, Denise Steigerwald changed the layout of the files so that they were sorted by category (air temperatures, humidity, radiation, wind etc.) rather than by year. Files containing monthly and daily averages were generated and minor adjustments were made to the metadata.

On June 1, 2000, relative humidity (RH) values were corrected for a systematic error in the measurement created by an instrument manufacturer error. All RH data with air temperatures below freezing were corrected using the vapor pressure over ice (rather than over water which was used initially). The error became quite large for very cold temperatures (the correction could grow to around 30%). The formula used for the correction was:

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.

LAKE VIDA

On September 6, 1999, the data manager added the 1998-1999 data to this dataset. In the process, she did some fine-tuning of the data, which included:

Addition of PAR values between Nov 24, 1997 @ 11:30 and Jan 13, 1998 @ 12:00. This was done at the request of Thomas Nylen.

For example, with an air temperature of -2.3 and RH_orig of 50.6, the RH_corr will be 51.7. Records that showed corrected RH values greater than or equal to 100 were changed to 99.99 and flagged.