FREE AIR CO2 ENRICHMENT (FACE) DATA REPORT:
                             DAILY LEAF AREA INDEX 
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QUALITY-ASSURANCE CHECKS AND DATA-PROCESSING ACTIVITIES PERFORMED BY THE FACE 
   PROJECT AND CDIAC
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X-Y scattergrams of daily leaf area (LAI) were used to check for outliers, 
and the scattergrams were evaluated for consistency.


LIST OF FILES 
-------------

Leaf area data are available for 1999-2007.  There is a daily file 
for each year which contains the leaf area index values (m2/m2).

This report documents 9 files with filenames of the form lai_A.dat, where A 
denotes the year (1999 through 2007).  The files are as follows:

lai_1999.dat       1999 daily LAI data
lai_2000.dat       2000 daily LAI data
lai_2001.dat       2001 daily LAI data
lai_2002.dat       2002 daily LAI data 
lai_2003.dat       2003 daily LAI data 
lai_2004.dat       2004 daily LAI data 
lai_2005.dat       2005 daily LAI data 
lai_2006.dat       2006 daily LAI data 
lai_2007.dat       2007 daily LAI data 


DESCRIPTION and FORMAT OF THE ASCII DATA FILES
----------------------------------------------


Leaf area index (LAI, total one-sided leaf area above a unit of ground area)
was calculated for each plot for every day of the growing season.
Leaf area production in the spring was calculated from the fractional
transmittance of PAR (T), which was calculated from daily total PAR above
and below the canopy. A curve was fit to ln(T)/-k data, where
the extinction coefficient k was set such that maximum leaf area
production at budset (early to mid July) was equal to that determined
from litter basket collections. A canopy-averaged value of leaf mass per
unit leaf area was used to convert abscised leaf mass in litter baskets to
green leaf area. A curve was fit through litter basket data to generate
cumulative daily leaf area loss, which was subtracted from the leaf area
production curve to generate daily LAI.

The data were generated for the elevated CO2 rings 1 and 2, and 
the ambient CO2 rings 3, 4, and 5.  The following reference describes 
these data in more detail:  Norby RJ, Sholtis JD, Gunderson CA,
Jawdy SS. 2003. Leaf dynamics of a deciduous forest canopy: no
response to elevated CO2. Oecologia, DOI 10.1007/s00442-003-1296-2


Contents and format of the daily files, lai_*.dat.

Variable   Variable  Variable  Starting  Ending  Units      Definition and
           type      width     column    column             comments

YEAR       Integer   4         1         4       y          Year
DOY        Integer   3         6         8       d          Day of the year
                                                            (1 = 1 January, 
                                                            ..., 365 or 366 
                                                            = 31 December)
RING       Integer   1         12        12                 Experimental ring
                                                            1 = elevated CO2
                                                            2 = elevated CO2
                                                            3 = ambient CO2
                                                            4 = ambient CO2
                                                            5 = ambient CO2
LAI        Real      5         16        20      m2/m2      Leaf area index 


PARTIAL LISTINGS OF THE ASCII DATA FILES
----------------------------------------


Format and contents of the ASCII hourly data file lai_1999.dat.

First five data records:

1999 112   1    0.00
1999 112   2    0.00
1999 112   3    0.00
1999 112   4    0.00
1999 112   5    0.03

Last five data records:

1999 318   1    0.04
1999 318   2    0.07
1999 318   3    0.05
1999 318   4    0.10
1999 318   5    0.03

**********

Format and contents of the ASCII hourly data file lai_2000.dat.

First five data records:

2000 117   1    0.03
2000 117   2    0.21
2000 117   3    0.04
2000 117   4    0.08
2000 117   5    0.21

Last five data records:

2000 312   1    0.00
2000 312   2    0.02
2000 312   3    0.01
2000 312   4    0.00
2000 312   5    0.00

**********

Format and contents of the ASCII hourly data file lai_2001.dat.

First five data records:

2001 112   1    0.00
2001 112   2    0.00
2001 112   3    0.26
2001 112   4    0.15
2001 112   5    0.00

Last five data records:

2001 314   1    0.01
2001 314   2    0.07
2001 314   3    0.00
2001 314   4    0.06
2001 314   5    0.00

**********

Format and contents of the ASCII hourly data file lai_2002.dat.

First five data records:

2002 108   1    0.00
2002 108   2    0.00
2002 108   3    0.00
2002 108   4    0.00
2002 108   5    0.11

Last five data records:

2002 331   1    0.00
2002 331   2    0.00
2002 331   3    0.00
2002 331   4    0.00
2002 331   5    0.01

**********

Format and contents of the ASCII hourly data file lai_2003.dat.

First five data records:

2003 108   1    0.02
2003 108   2    0.06
2003 108   3    0.00
2003 108   4    0.00
2003 108   5    0.00

Last five data records:

2003 317   1    0.01
2003 317   2    0.01
2003 317   3    0.01
2003 317   4    0.02
2003 317   5    0.01

**********

Format and contents of the ASCII hourly data file lai_2004.dat.

First five data records:

2004 105   1    0.00
2004 105   2    0.00
2004 105   3    0.10
2004 105   4    0.00
2004 105   5    0.00

Last five data records:

2004 299   1    0.17
2004 299   2    0.20
2004 299   3    0.15
2004 299   4    0.18
2004 299   5    0.12

**********

Format and contents of the ASCII hourly data file lai_2005.dat.

First five data records:

2005 101   1    0.00
2005 101   2    0.00
2005 101   3    0.12
2005 101   4    0.00
2005 101   5    0.00

Last five data records:

2005 321   1    0.01
2005 321   2    0.01
2005 321   3    0.01
2005 321   4    0.02
2005 321   5    0.01

**********

Format and contents of the ASCII hourly data file lai_2006.dat.

First five data records:

2006 104   1    0.00
2006 104   2    0.00
2006 104   3    0.05
2006 104   4    0.00
2006 104   5    0.00

Last five data records:

2006 316   1    0.01
2006 316   2    0.03
2006 316   3    0.03
2006 316   4    0.00
2006 316   5    0.01

**********

Format and contents of the ASCII hourly data file lai_2007.dat.

First five data records:

2007 104   1    0.01
2007 104   2    0.00
2007 104   3    0.01
2007 104   4    0.00
2007 104   5    0.00

Last five data records:

2007 333   1    0.01
2007 333   2    0.01
2007 333   3    0.02
2007 333   4    0.01
2007 333   5    0.01

**********


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Since these daily leaf area index files are space-delimited ASCII text, 
the files can be imported to spreadsheet software such as Excel or Lotus
for processing.


SAS, FORTRAN, and C CODES TO ACCESS THE DATA
--------------------------------------------


The following is SAS code to read daily files, lai_*.dat.


/* SAS CODE TO READ FILE lai_2002.dat. */

DATA LAIDAT;

   INFILE "lai_2002.dat";

   IF _N_ = 1 THEN DO;
      INPUT ////////;  /* READ HEADER INFORMATION */
   END;

   INPUT YEAR 1-4 DOY 6-8 RING 12 LAI 16-20; 

RUN;


**********

The following is FORTRAN code to read daily files, lai_*.dat.


      PROGRAM LAIDAT

C     FORTRAN CODE TO READ THE FILE lai_2002.dat.

      REAL LAI 

      INTEGER YEAR, DOY, RING

      CHARACTER*62 HEADER

      OPEN(UNIT = 2, FILE = 'lai_2002.dat', STATUS = 'OLD')

      DO I = 1,9
         READ(2,'(A)') HEADER
      ENDDO

   10 READ(2,*, END = 20)
     #   YEAR, DOY, RING, LAI 

      GO TO 10

   20 CLOSE(2)

      STOP
      END


**********

The following is C code to read daily files, lai_*.dat.


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* C program to read lai_2002.dat. */

int main(int argc, char *argv[])

{

   int rec;
   int YEAR, DOY, RING;

   float LAI;

   char header[65];

   FILE *lai_fp;

   if((lai_fp = fopen("./lai_2002.dat", "r")) == NULL) {
      fprintf(stderr, "Error opening file lai_2002.dat.\n");
      exit(EXIT_FAILURE);
   }

   for(rec = 1; rec <= 9; rec++) {
      fgets(header, 64, lai_fp);
      header[strlen(header)] = '\0'; 
   }

   while(!feof(lai_fp)) {
      if (fscanf(lai_fp, "%d %d %d %f\n", 
         &YEAR, &DOY, &RING, &LAI) == 4);  
      else
         fprintf(stderr, "Check the number of variables in lai_2002.dat\n");
   }

   return;
}

**********