D-15 
Data Impoit 
Report* 
Interpolate 
0 DisttJved Oxygen DO 1 
Compute Pei cartage Q»ange 
• ■ ‘ ■ . ■&&'£$ 
CHF.SAPf.AKF BAY PROGRAM INTERPOLATOR 
hyi/- . . - - - 
Ge<xjidphr 
lr T"' 1 Fitf-. I fhj »C \Vcl30V>do 9707 9709 >ls 
nf«< Dflrts I Ml ICWolXVCO M 
■ Oi/pU ffc I eH) 1 CWolMKir<|»e!' 
■ . -v m h m* mg 
is- . ■ 'rKt.-.i •*. i&i 
Figure D-16. Math screen with files 
chosen to "Change Over Time". The 
bdo-9707-9709.fls file contains file 
names of dissolved oxygen .EST files. 
The corresponding Julian dates for 
these .EST files are read from the do.jul 
file. In this example, a new .EST file - 
Change.est - is created which contains 
the linear trend for each cell over the 
time interval of the bdo-9707-9709.fls 
file. The Change.est cell values are per¬ 
centage change over time, categorized 
by the selection criteria identified in 
the pc.rng file. In this example, "Ignore 
missing values" has not been selected. 
CHESAPEAKE BAY 
Water Quality Analysis 
Total Phosphorus Perront Change Jul 2.1984 Dec 18, 1997 
PLAMVIFW 
Svs Cfuehanna 
Legend 
CD >103: 
■■ 53T-103: 
CD 03T-53: 
a 03:~5* 
a 5*~10Z 
E3 >103: 
E3 Not Calculated 
Atlantic 
Patuxent 
. Potomac 
A 
Rappahannock 
jf- * James 
Figure D-17. Plot of total phosphorus as a "Change Over Time". In this 
example, a new .EST file - tp8497.est - was created which contains the linear 
trend for each cell over the time interval (July 1984 through December 1997) 
of the tp8497.fls file. The tp8497.est cell values are percentage change over 
time, categorized by the selection criteria identified in the pc.rng file. The 
percentage change categories for total phosphorus mass (kg) are: >10% 
increase (red); 5 to 10% increase (pink); 0 to 5% increase (yellow); 0 to 5% 
decrease (light blue); 5 to 10% decrease (dark blue); and greater than 10% 
decrease (green). In this example, "Ignore missing values" was selected so 
that a trend on any available data was calculated. 
appendix d 
User Guide and Documentation for the Chesapeake Bay Interpolator 
