ASCII Soundings

Binod Pokharel

Two ASCII-WWMPP sounding sites

72 MGAUSsoundings

(ASCII)

GPS-based soundings (GRAW)(1 sounding per RSE case)

ASCII Window C only

ASCII winds(220-270°)

MGAUS sounding site Battle Pass

43 km

Dixon Airportradiosonde launch site+ weather station (10 m wind, 2m q, T, net radiationcontinuously op.)

runway

views from this spot

Bridger Peak (38 km)Battle Mtn (13 km)Battle Town site (41 km)

Sandstone ridge

Red Mtn (38 km)

Elkhead Range

looking NE (downwind) looking south

How to use the 72 sondes?

• 72 units/15 IOPs = 4.8 sondes per IOP• proposal: we do NOT use a sonde for case calling • suggested distribution:

type of IOP # IOPs* # sondes first sonde frequency

double-flight up to 5 6 0.5 hr after IOP start

1.5 hrs

single-flight up to 10 4 1.0 hr after IOP start

2 hrs

blowing snow

2 2 0.5 hr after IOP start

2 hrs

* in the best-case scenario, we ‘ll need 74 sondes, that is 5*6 + 10*4 + 2*2 …

Radiosonde Training• Training in Boulder with Tim Lim

Temperature Sensor

Humidity Sensors

GPS Antenna

Battery Case

Antenna

GC25 Interface

Vaisala Ground Check set (GC25) for radiosonde

Ready to Launch

key sounding parameters

• wind speed and direction at 700 mb• temperature at 700 mb

• ST wind speed and direction• LCL level (m) and LCL temperature • ST Brunt-Väisälä frequency• ST Richardson number• temperature at the level of the generators

ST=surface to mountain top level average

} case calling parameters

sample sounding (test case in Boulder)

Sounding Parameters

Parameters Altitude, m Altitude for ASCIIGround 1638 1987.3LCL 5123.14 N/AMountain 5354 3354.02

AgI Generators Altitude, m T, oCGen1 2435.4 1.98Gen2 2557.3 1.55Gen3 2431.4 1.98

From Boulder Sounding, Key parameters summaryDate: 20111018 Time: 175416Z

Paremeters 700 mb Average (ST) LCL (5123.14 m)Wind Speed, m/s 4.4 14.09 26.24Wind Direction 316.15 269.25 344.53Temparature, oC -3.46 -6.02 -15.2ST N (s-1) 0.01097 ST Fr 0.346 ST Ri 2.581

ST: Average value is calculated from surface to mountain top

• LCL is calculated assuming lowest 50mb are well mixed

• Mean θ and mr are calculated in the lowest 50 mb

• Surface T and Td is computed from mean theta and mr

LCL - 542.580 mb

Stable as Ri>0.25

Flow blocked as Fr<1

challenges, limitations• Cold and windy!• If instrument does not work after balloon launch• Need to launch another one immediately• no data transmission when GPS signal is lost• Some variables are available (pressure, Temperature, RH), but others are

not (Wind, altitude..)

• Sounding plot is available after the balloon reach tropopause• It takes about 90 minutes to reach tropopause• Calculated parameter is not available immediately• Temperature, wind speed, and wind direction at 700 mb can be available

from the display plot when balloon is ascending, but difficult to get the actual wind values

• Data will be processed using some software to get the actual wind data

Plans

• Mock IOP at Dixon airport with Tim Lim during the week of 19 Dec

• 2 persons on site most of the time:– Binod Pokharel– Other one from U Illinois

• Time to prepare sonde ~ 1 hour• Travel time from Savery to Dixon Airport ~10 min• Have to be ready ~2 hours before first sonde

Suggestions?