humidity

High frequency measurements from Lake Vida Meteorological Station (VIAM) in Victoria Valley, Antarctica from 1995 to present

Abstract: 

As part of the McMurdo Dry Valleys Long Term Ecological Research program, meteorological data are collected from various locations throughout the McMurdo Dry Valleys of Antarctica. This data package contains 15-minute data from the Lake Vida Meteorological Station (VIAM), located in Victoria Valley.

Dataset ID: 

7016

Associated Personnel: 

838
839
231
12
65
232

Short name: 

VIAM

Purpose: 

Meteorological data are collected year-round at each of MCM LTER stations. Data are manually downloaded from the meteorological stations during the austral summer. Raw 15 minute data (Level 0) is processed and provided as Level 1 data on the MCM LTER website. Field notes, sensor information, processing procedures, QA/QC, and metadata is provided in the Meteorological Post Processing Documentation and Task Lists for each field season at the following address: http://www.mcmlter.org/data/meteorology/tasks/task_lists.htm 

Methods: 

The Lake Vida meteorological station was added to the McMurdo Dry Valley network in the 1995-1996 field season. It was established on the shore of Lake Vida in Victoria Valley, one of the largest lakes in the dry valleys, recently discovered to have a 19 m ice cover over a hypersaline brine of undetermined depth. The station was set up to sample sensors every 30 seconds and send summary statistics (for example, averages and maximums) to solid-state storage modules every 15 minutes. This has resulted in approximately 20 values being recorded for final storage in every output interval.

Sampling and Averaging Intervals For Sampling frequency and Data Logger output and averaging intervals please visit: http://mcmlter.lternet.edu/data/meteorology/methods/Interval_Dates.pdf

Seasonal Task Summary To view the data post-processing steps for each season please visit: http://mcmlter.lternet.edu/data/meteorology/tasks/task_lists.htm

Data sources: 

VIAM_AIRT
VIAM_RADN
VIAM_RH
VIAM_SOILT
VIAM_SURFCHANGE
VIAM_WIND

Maintenance: 

 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:
       
1. Addition of  PAR values between Nov 24, 1997 @ 11:30 and Jan 13, 1998 @ 12:00. Thiswas done at the request of Thomas Nylen.
       
On June 1, 2000, the 1999-2000 data was posted. In the process, Denise  Steigerwald changed thelayout of the files so that they were sorted by category (ait temperatures, humidity, radiation,wind etc.) rather than by year. Files containing monthly and daily averages were generated andminor 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 whichwas used initially). The error became quite large for very cold temperatures (the correction couldgrow to around 30%). The formula used for the correction was:
 
       RH_corr=RH_orig/((A*temp*temp)+(B*temp)+C) where 
       RH_corr = corrected relative humidity
       RH_orig = original relative humidity 
       temp = air temperature 
       A = 4.165E-5
       B = 9.7E-3
       C = 1.0
 
 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 99.99and 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, maximumsand counts of the records represented in the Oracle database's meteorology tables.

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