### Particle Cross Section Regression Line

Posted:

**July 11th, 2013, 11:15 am**How is the location of the red regression line shown in the particle cross section plot determined?

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Posted: **July 11th, 2013, 11:15 am**

How is the location of the red regression line shown in the particle cross section plot determined?

Posted: **October 23rd, 2013, 7:29 am**

The computation of the regression line through the particle positions is determined using the following fortran routine....

DO N=1,NUMTIM

! time period index record

READ(32)NUMPAR,NUMPOL,IYR,IMO,IDA,IHR

CNTR=0.0

SUMX=0.0

SUMY=0.0

SUMXY=0.0

SUMX2=0.0

SUMY2=0.0

DO J=1,NUMPAR

READ(32)(MASS(I),I=1,NUMPOL)

READ(32)TLAT,TLON,ZLVL,SIGH,SIGV,SIGX

READ(32)PAGE,HDWP,PTYP,PGRD,NSORT

IF(SUM(MASS).GT.0.0)THEN

CALL CLL2XY(PARMAP,TLAT,TLON,X1,Y1)

! regression sums

CNTR=CNTR+1.0

SUMX=SUMX+X1

SUMY=SUMY+Y1

SUMXY=SUMXY+X1*Y1

SUMX2=SUMX2+X1*X1

SUMY2=SUMY2+Y1*Y1

END IF

END DO

! regression line to determine cross-section

IF(CNTR.GE.2.0)THEN

SLOPE(N)=(CNTR*SUMXY-SUMX*SUMY)/(CNTR*SUMX2-SUMX*SUMX)

YNODE(N)=SUMY/CNTR-SLOPE(N)*SUMX/CNTR

ELSE

SLOPE(N)=1.0

YNODE(N)=0.0

END IF

END DO

DO N=1,NUMTIM

! time period index record

READ(32)NUMPAR,NUMPOL,IYR,IMO,IDA,IHR

CNTR=0.0

SUMX=0.0

SUMY=0.0

SUMXY=0.0

SUMX2=0.0

SUMY2=0.0

DO J=1,NUMPAR

READ(32)(MASS(I),I=1,NUMPOL)

READ(32)TLAT,TLON,ZLVL,SIGH,SIGV,SIGX

READ(32)PAGE,HDWP,PTYP,PGRD,NSORT

IF(SUM(MASS).GT.0.0)THEN

CALL CLL2XY(PARMAP,TLAT,TLON,X1,Y1)

! regression sums

CNTR=CNTR+1.0

SUMX=SUMX+X1

SUMY=SUMY+Y1

SUMXY=SUMXY+X1*Y1

SUMX2=SUMX2+X1*X1

SUMY2=SUMY2+Y1*Y1

END IF

END DO

! regression line to determine cross-section

IF(CNTR.GE.2.0)THEN

SLOPE(N)=(CNTR*SUMXY-SUMX*SUMY)/(CNTR*SUMX2-SUMX*SUMX)

YNODE(N)=SUMY/CNTR-SLOPE(N)*SUMX/CNTR

ELSE

SLOPE(N)=1.0

YNODE(N)=0.0

END IF

END DO