11-7-95
HALF-HOURLY SITE DATA FILE DESCRIPTION

   The purpose of these data is to provide full year 1994 meteorological data
for the boreas modeling group to drive models at each of the boreas flux tower
sites. The files in this directory represent half-hourly 1994 
meteorological data from the boreas SRC and TF towers. The half hourly 
data (*.5hr) are formated as:

COL	VAR
--------------------------------------------
1 	DOY
2 	Time (GMT)
3 	Identification flag for time variable
4 	Incoming par (J)
5 	Identification flag for par variable
6 	Incoming solar rad. (J)
7 	Identification flag for solar variable
8 	Incoming long-wave radiation (J)
9 	Identification flag for long-wave variable.
10 	Air temperature (C)
11 	Identification flag for air temperature
12 	Windspeed (m/s)	
13 	Identification flag for windspeed 
14 	Relative humidity (%)	
15 	Identification flag for relative humidity (%) 
16 	Belfort precipitation (mm)
17 	Identification flag for belfort precip.
18 	Tipping bucket precipitation (mm)
19 	Identification flag for tipping bucket precipitation
--------------------------------------------

The identification flags indicate which tower the data were taken from. The 
identification flags are defined as follows:

PA = soas SRC tower
NP = sojp SRC tower
NL = nojp SRC tower
TH = Thompson SRC tower
NFEN = nfen TF tower
NOBS = nobs TF tower
NOJP = nojp TF tower
NYJP = nyjp TF tower
SFEN = sfen TF tower
SOAS = soas TF tower
SOBS = sobs TF tower
SOJP = sojp TF tower
SYAS = syas TF tower
NSA = combination of NL TH PA NP and NOBS
SSA = combination of PA NP NL TH and SOAS 
INT = NSA with interpolated missing values (used as a catch all)
EST = Estimated incoming long-wave radiation (See below)
INTS = Par radiation data estimated from solar radiation (See below) 
INTP = Solar radiation data estimated from par radiation (See below)
BAD = Missing or bad data (should only occur with 0.5hr belfort and 
      tipping bucket precipitation data)
----------------------------------------------------------------------------

Complete half-hourly data files were created by placing several data files
together in series for each tower site. Missing values were then selected
from adjacent data files with complete data for the same time period. 
Preceding data were always favored first in the selection process.
Half-hourly data for each site were assembled in the following series'
to create complete data files for each tower site:  

nfen site: NFEN NOBS NL NSA INT
nobs site: NOBS NL NYJP NFEN INT
nojp site: NL NOBS NYJP NFEN INT
nyjp site: NYJP NL NFEN NOBS INT
sfen site: SFEN SYAS PA SOAS INT
soas site: PA SOAS SYAS SOBS INT
sobs site: SOBS NP SOAS SYAS INT
sojp site: NP SOBS SOAS SOJP INT
syas site: SYAS PA SOAS SOBS INT

Note: Relative humidity data for NFEN and NYJP appeared 
      unreasonably low and were not used. 
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   Long-wave incoming radiation (lw) measurement data from NL and NP were used to
represent long-wave radiation characteristics for tower sites in the boreas 
northern and southern study sites, respectively. Missing values were estimated 
using a multiple linear regression fit between measured long-wave Rad., estimated 
clear-sky long-wave Rad., and relative humidity:

     lw.est = 80.3855+0.7521*lw.clr+0.4525*RH

   where: lw.est = estimated lw irradiance (W/m2)
	  lw.clr = estimated clear-sky lw irradiance (W/m2)
	  RH = measured relative humidity (%) 

lw.clr was estimated from air temperature and relative humidity measurements using
an approach described by Marks and Dozier (1979). lw.est values are
designated with an "EST" flag.

   Incoming solar and par radiation files were created by combining NL TH PA NP and 
NOBS files.  Missing solar radiation that was not available was estimated as 
(par*2.0) and missing par radiation as (solin/2.0). These estimated values are 
identified as INTP (estimated from par) and INTS (estimated from solar rad).
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   Tower site files often contained temperature, wind and humidity data
at 1 or more heights. When data at more than one height were available, data
were taken from the upper height which corresponded most closely with the top 
of the canopy or the upper level at which water and co2 fluxes were measured.
No attempt has been made to reconcile data differences due to different 
measurement heights. These files have been generated "as is" from the boreas
tower site data. Only minimal error checking has been done. 
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