Figure 16. Temperatures in and around basin II compared with the 2-cm temperature at Z

air temperature along the 045 radial be-

tween Z and W, the 1.25-m temperature at

2 m Temp., (Z) 267 m

W, and the 1.25-m temperature observed

2 m Temp., (z) 245 m (0.27 km, 045)

2 m Temp., (W) 234 m (0.61 km, 090)

at e (projected to the 090 radial in Fig. 15)

2 m Temp., (e) 254 m (1.04 km, 120)

are plotted against this 2-cm temperature

in Figure 16. The elevation of each mea-

suring point and its relative direction from

Z are tabulated in the data block in Figure

16. The 1.25-m air temperature in the ba-

sin (W) is most frequently less than the

temperatures around the basin, and is 1 to

5C less than the 2-cm temperature above

the basin in many cases.

The observation path was continued be-

yond the apex of observation A to the In-

dian Pond basin (X) at a on several

mornings. The observations along Aa

were used in conjunction with the obser-

vations along the usual path to construct

a temperaturetopographic cross-sectional

2 cm Air Temperature (C), 265 m (Z reference)

analysis. This enlarged elevation section

Figure 16. Temperatures in and around basin II compared with

is shown in Figure 17. The temperatures

the 2-cm temperature at Z. The temperature in basin II is

observed at 0630 on 7 February 1993, the

consistently less than the 2-cm temperature on the slope above.

coldest morning of the three winters (1990

1993), are plotted on the cross section in

Figure 17, and as one of the significant

basin is shown in the east (090) radial section;

vertical profiles of air temperature in the Con-

the northeast radial section (045) shows the broad-

necticut Valley, in Figure 18a.

ening of the basin at W, and the north (360) ra-

Very strong, cold advection with surface wind

dial the narrowing of the basin at the entrance to

of 510 m/s was present throughout the area on 6

the valley. The narrow valley is shown in the 315

February 1993. At 2130 EST, the surface winds

radial, and the valley begins to broaden into a

had diminished, and the temperature at W was

basin (III) in the 270 radial section. The nature of

30.8C, this being the lesser of several air tem-

Basin II surrounding W is not readily apparent in

peratures measured in the vicinity that evening.

a westeast elevation section, but the bounded

Warm advection increased the temperature at Mt.

Washington to 20C by 0630 on 7 February, but

basin is quite apparent in the cross section along

the 045 radial in Figure 15.

radiational cooling and inversion strengthening

The basin (II) surrounding W may receive air

continued in the study area. Air temperature be-

draining from the adjacent slopes (Yasuda et al.

low the ridge tops was consistently less than

30C during the 06150700 period of observa-

1986) and retains it through boundary damming

by the more wooded terrain (Baines 1979, Raynor

tion. The points Aa on the posterior of the ridge

1971) along the valley (Yasuda et al. 1986) which

from A as in Figure 17 are shown by open circles

drains the basin on the west. A thin stagnant

in Figure 18a. The coldest air was in basins (I) and

layer in the bottom of the basin could then con-

(II), evident in both Figure 17 and Figure 18a.

tain cooler air than found nearby. A test of this

Lapse structure was present from river level to

premise was performed during winter 1993. A

230 m although considerable temperature differ-

series of temperature measurements, 2 cm and 2

ences occurred at each elevation. Examining the

m above the snow, were obtained at the fixed site

cross section of these air temperatures with re-

Z to compare near snow temperature along the

spect to terrain in Figure 17 indicates that the

slope to the air temperature in the basin. The

isotherms quite consistently intersect the ridges,

temperature measured at 2 cm at point Z during

and that the Clay Hollow and Indian Pond sides

JanuaryFebruary 1993 is defined as the reference,

of the barrier ridge have similar air temperature

and plotted as the abscissa in Figure 16. The cor-

structure. The inversion isotherms above Clay

responding 2-m air temperature at Z, the 1.25-m

Hollow and Indian Pond are quite closely packed,