raytheon polar services company

Raytheon Polar Services Company

UNITED STATES ANTARCTIC PROGRAM

2004 AWS-AMRC-AMPS Annual Joint

Meeting - Charleston, SC

South Pole Meteorology Kathie Hill

9 June 2004 Raytheon Polar Services Company

Denver, Colorado

Photo: Kris Perry, South Pole winter over Meteorologist

Advancing Polar Science


We will discuss…….

• Objectives of the South Pole Meteorology department• South Pole Met support and data integrity issues• Implemented upgrades and those to come• Comparison study and planned switch over to new Met

system



South Pole Meteorology Department Objectives

• Support– Aviation– Station Ops– Science – Antarctic

Forecasting– 47 Year

Data Record

– Annual race around the world



Contributing Factors to Inconsistencies in the South

Pole Data Record

• Inconsistency in:– Observing practices season to

season– Climatological calculations over

the 47 year history

• Lack of documentation and tracking:– Instrument modification,

replacement and performance– Station practices

• Improperly maintained instrumentation and software– Inability to obtain maintenance

and calibration information on current instrumentation suite

– Processing software modification uncontrolled



South Pole Meteorology Improvements

• SPSM Met system Implementation (Jan 04)– Integrates surface data– Provides 1-minute resolution

data– Desktop display of surface data– Addition of optical instruments

(clouds, visibility)– Provides redundancy for winds,

temps and pressure

• Historical data validation project (in process)– Identifying incorrect climate

data– Build more consistency in

historical database



South Pole Meteorology Improvements

• Instrumentation tracking database (FY 05)– Provides reporting on instrument maintenance, calibration and

performance to researchers– Ensures maintenance and calibration schedules are maintained

• Station observer practices defined and documented (FY 04)– Builds consistency in surface data season to season

• DIGI-Cora III Upper Air System Installation (FY 04)– Improved radiosonde technology and reporting capabilities– Sonde calibration prior to launch

• Version controlled surface observation processing software (FY 04)– Ensure consistency in climate data processing

• Published data comparison study (FY 05)– Clean switch over with documented comparison between the old and

new systems



Installation of the new SPSM Met system (OS-21)

• OS-21 was installed at South Pole in January, 04

– System comprised of two instrumentation suites

Skiway (approach end): winds, visibility, clouds, ambient light (AL)Visibility, clouds and AL function only during flight season, winds function year round

Clean Air: winds, pressure, temps, RH, solar radiationAll instruments function year round




Sensor suite and systems for OS-21

• Visibility sensor: Belfort, model 95000-1

• Ambient light sensor: Belfort, model 6300

• Ceilometer: Eliasson, CBME-40A

• Solar Radiation sensor: Li-Cor pyranometer, LI-200SA

• Barometers: Druck, RPT-410

• Temp/RH sensors: RM Young, 43440

• Windbirds: RM Young, 05103

• SQL 2000 Server and database

• Visual displays in Met office and Comms



OS-21 – Parts is parts

• Field Data Collection Unit (FDCU): Collects, processes sensor data and sends to the Terminal Data Acquisition Unit (TDAU) via Ethernet connection. FDCU houses barometers (3), Zeno 3200 datalogger, serial sensor expansion module (SSEM), comms links and power supply. Resides at the bottom of tower.

• Terminal Data Acquisition Unit (TDAU): Responsible for data acquisition, processing, formatting, sorting, distribution of data received from FDCU. Is MS SQL 2000 Server, resides in the NOC.



Visual Display of OS-21

Includes Network Connection to South Pole LAN providing graphical displays (via AWA software) directly to Met office and Comms

Allows Comms to provide wind and altimeter data on demand with no need to contact Met office. Avoids conversion errors by providing calculated altimeter as opposed to a visual chart conversion




Initial OS-21 Comparisons - Visibility

Limitations – provided by Coastal Environmental Systems

• Isolated fog causes the most problems:

Lower visibility if fog is localized to sensorFog confined to skiway may go unreported

• When visibility changes rapidly, OS-21 observation will lag actual weather (several minutes). Algorithm responds more quickly to rapidly decreasing visibility than rapidly increasing visibility.

• On bright, sunny days with haze, sensor will report higher visibility than observer. NWS advises: Reduce reported vis 50% if it’s bright enough to wear sunglasses and there’s haze or thin fog with clear sky above (a typical day during the South Pole summer).



Visibility: SPSMS vs. Observer Initial Analysis

• 337 METAR observations were compared for the month of February, 2004

• Very limited amount of data, study is extremely limited and high level at this time

Photo: Paddy Douglas, South Pole Logistics Supervisor



Initial Comparison Results Visibility - SPSMS vs. Observer

• 41% of observations matched exactly

• 15.4% of observations had SPSMS calling lower visibilities than observer

• 43.6% of observations had Observer calling lower visibilities than SPSMS

–96.4% of matching observations called unlimited (9999) visibilities

–61.5% observer is calling unlimited (9999) visibility

–51% SPSMS is calling unlimited (9999) visibility




Visibility – Frequency Distribution

• 41% no difference – overwhelmingly during high visibility situations

• 33% within 1 ¼ miles

• 26% differ between 1 ¼ SM 6 SM – need to explore these situations more extensively

Frequency Distribution of Meters Difference SPSMS vs. Observer Visibility

41%

17%

16%

5%

6%

2%

7%

2%

2%

2%

0 M

< 1000 M

1000 < 2000 M

2000 < 3000 M

3000 < 4000 M

4000 < 5000 M

5000 < 6000 M

6000 < 7000 M

7000 < 8000 M

8000 < 9000 M



Visibility Comparative Breakdown

• During high visibility situations, observer and OS-21 compare extremely well except for a few specific circumstances

• OS-21 calling lower visibility and observer is calling unlimited, it is probably due to prop wash or localized ice crystals near the instrument, yet to be proved out next summer

• Observer calling lower visibilities than OS-21– 51% show OS-21 calling unlimited

visibilities while the observer is calling on average over 1 ¾ SM less (prop wash?)

• Calls for more intensive investigation FY04, can’t just assume OS-21 is correct, needs to be validated with observed visibilities



Performance of OS-21 Ceilometer

• Ceilometer – South Pole cloud heights difficult to

determine – Observer support only, no plans to rely on

ceilometer for cloud observations– Currently, data only available during flight

season– Readings are a result of a 30 minute average– Cannot report cloud types, therefore cannot

anticipate changes in weather based impending cloud conditions.

– Can’t distinguish between clear and unable to determine

– May lag actual weather due to rapid changes– Laser Beam Ceilometer only sees one spot.

But 30-min. average creates accurate observation in stable conditions.



Current South Pole Ceilometer Status

• Began experiencing issues with the ceilometer on February 2nd

• Limited comparisons at this time • All that is currently known is that

ceilometer did determine clouds vs clear consistently with observer and at a coverage close to what observer called

• Fog can cause inaccurate readings• Pole ceilometer currently in storage

for the winter• Will add insulated “Sponge Bob

pants” FY05 and bring back on line• Will attempt to keep ceilometer

running as long in to winter as possible




Outstanding Issues

• Report file formats will be changing (surface and upper air)

• Difference in calculation of climatological averages– NCDC method– WMO method– Re-issue of previous years climate

files

• Corrected climate data files• Disparate data records existing

within different organizations (NCDC, AMRC, BAS)

• Need published comprehensive comparison study

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