WMOD00582

• Title: Natural Variability of Thermodynamic Features Affecting Convetive Cloud Growth and Dynamic Seeding: A Comparative Summary of Three High Plain Sites from 1975 to 1977
• Date: 9/9/1981
• Weather Modification - Doc Type: Report

978

JOURNAL OF APPLIED METEOROLOGY

TABLE 5. Spatial differences in 1975 Montana mesonet thermodynamic and cloud model variables.

Thermodynamic and model variables

Base height (km)
Base temperature eC)
Surface convective temperature.(oC)
Temperature rise to surface
convective temperature
Mean mi"ing ratio lowest 50 mb
(g kg-I)
Surface mixing ratio
Mean lapse rate lowest 50 mb
[OC (100 m)-I]
Mean lapse rate lowest 100 mb
Mean lapse rate 100-150 mb AGL
Mean lapse rate 150-200 mb AGL
Mean lapse rate 400-500 mb AGL
Mean lapse rate 500-600 mb AGL
Mean 'mixing ratio lowest 50 mb
(g kg-I)
Mean mixing ratio lowest 100 mb
Mean mixing ratio 100-150 mb AGL
Mean mixing ratio 150-200 mb AGL
Mean mixing ratio 400-500 mb AGL
Mean mixing ratio 500-600 mb AGL
Cloud-top height (km)
DMP (km)
Maximum updraft speed (m S-I)
Height of maximum updraft speed
(m S-I)
Temperature at maximum updraft
speed eC)
Natural depth of cloud (km)
Modified depth of cloud (km)
Natural cloud-top temperatures (OC)
Total' supercooled cloud water
(g kg-I)
Total supercooled rainwater (g kg-I)

MLS vs GD

.&

0.44
2.6
2.5

2.5

1.3
1.3

0.4
0.2
0.2
0.1
0.06
0.04

1.3
1.1
1.2
1.2
0.5
0.2
1.7
0.9
5.2

1.4

17.3
. 1.8
1.8
12.3

18.5
3.5

Mesonet rawinsonde site comparison statistics

a

a/n r

.& = Mean absolute difference = [Z Base (MLS) - Z base (GD)]In.
a = Standard deviation of mean absolute difference.
a/n = Standard error of mean absolute difference.
r = Correlation coefficient.

0.37
2.3
2.1

0.05 0.71
0.28 0.66
0.26 0.90

2.1

0.26 0.86

1.2
1.8

0.15 0.77
0.22 0.75

0.4
0.2
0.1
0.2
0.06
0.06

0.05 0.87
0.02 0.89
0.01 0.72
0.02 0.42
0.01 0.45
0.01 0.40

1.2
1.0
1.1
1.0
0.4
0.3
1.5
1.2
4.0

0.15 ' 0.78
0.12 0.80
0.14 0.73
0.14 0.59
0.05 0.58
0.04 0.49
0.18 0.72
0.15 0.03
0.49 0.62

1.5

0.18 0.61

48.9
1.5
1.6
11.6

6.02 0.08
0.18 0.66
0.20 0.67
1.43 0.68

15.4
4.9

1.90 0.53
0.60 0.27

MLS vs PL

.&

0.43
2.7
2.1

3.2

1.3
1.8

0.4
0.3
0.1
0.2
0.05
0.05

1.3
1.1
1.2
1.0
0.5
0.2
2.3
0.8
5.5

1.6

26.9
2.4
2.4
16.4

23.5
3.6

a

a/n r

.&

0.39
2.6
1.8

2.1

1.2
1.7

0.4
0.2
0.1
0.1
0.5
0.5

1.2
0.9
1.0
1.1
0.3
0.2
1.7
0.6
4.5

0.8

13.0
1.7
1.6
12.2

17.5
2.5

VOLUME 20

J
.,

GD vs PL

a

a/n r

0.37
2.3
2.1

0.05 0.75
0.28 0.73
0.26 0.92

0.31
2.0
2.1

0.04 0.78
0.25 0.77
0.26 0.93

,2.1

0.26 0.84

1.8

0.22 0.90

1.4
1.8

0.17 0.79
0.22 0.74

1.0
1.2

0.12 0.87
0.15 0.85

0.4
0.2
0.1
0.1
0.06
0.Q7

0.05 0.88
0.02 0.87
0.01 0.69
0.01 0.49
0.01 0.60
0.01 0.37

0.4
0.2
0.1
0.1
0.06
0.Q7

0.05 0.88
0.02 0.91
0.01 0.78
0.01 0.69
0.01 0.55
0.01 0.62

1.3
1.1
1.3
0.9
0.5
0.2
2.0
1.2
4.4

0.16 0.81
0.14 0.83
0.16 0.61
0.11 0.66
0.06 0.56
0.02 0.50
0.25 0.57
0.15 0.07
0.54 0.62

1.0
0.7
1.2
1.1
0.3
0.2
1.6
1.2
3.6

0.12 0.87
0.09 0.90
0.15 0.76
0.14 0.63
0.04 0.81
0.Q2 0.75
0.20 0.74
0.15 0.01
0.44 0.76

1.6

0.20 0.55

1.0

0.12 0.82

66.4
2.0
2.1
14.9

8.17 0.07
0.25 0.49
0.26 0.49,
1.83 0.50

48.3
1.6
1.7
12.5

5.95 0.61
0.20 0.69
0.21 0.74
1.54 0.87

19.7
5.3

2.42 0.38
0.65 0.17

16.0
2.5

1.97 0.63
0.31 0.64

difference between 18 thermodynamic and 10 cloud-
model variables for rawinsondes observed simul-
taneously at Miles City (MLS); Glendive (GD), and
Plevna (PL) were computed for 66 cases. In each
case the absolute value of differences between
variables at MLS and GD, MLS and PL, and GD
and PL were computed. The mean absolute dif-
ference (6.), its standard deviation ((T), the standard
error ((TIn) and correlation coefficient (r) between
each site are tabulated in Table 5. In nearly all
cases, relatively large variations in thermodynamic
variables occurred between sites and the effect of
these variations on cloud model results was large.
The most important were cloud-base height and
temperature, cloud-top height and maximum verti-
cal velocity. There were relatively high correlations
between variables at different sites (r ;;. 0.8) in 22

comparisons. The best correlations occurred among
PBL parameters such as surface convective tem-
perature, mean lapse rates, and mixing ratios of the
lowest 5 -10 kPa. The poorest correlations oc-
curred among the mid-tropospheric lapse rates and
mixing ratios, DMP, temperature at the level of
maximum updraft and supercooled water of the
clouds.
No station appeared to have a systematic bias of
variables such as maXImum cloud"top height,
mean mixing ratio, or maximum updraft speed;
however, relatively large deviations from values at
MLS occurred at most observation times, sug-
gesting an apparently random synoptic-scale varia-
tion in samples. The range of the values also
changed from day to day indicating changes in
synoptic and mesoscale conditions. Multivariate