### Chapter 1. Overview of the 2003 Pacific TOST

1.  Introduction.

The 2003 Pacific THORPEX Operational Science Test,
<http://www-angler.larc.nasa.gov/thorpex/> is the first in a series of
Pacific and Atlantic observation campaigns in support of the WWRP/USRP
THORPEX Program. THORPEX -- a Global Atmospheric Research Program, is a
10 year international research program under the auspices of the World
Meteorological Organization/World Weather Research Program (WMO/WWRP) to
accelerate improvements in short range (up to 3 days), medium range (3-7
days) and extended range (two week) weather predictions and the societal
value of advanced forecast products. THORPEX will examine predictability
and observing system issues, and establish the potential to produce
significant statistically-verifiable improvements in forecasts of high
impact weather. The program builds upon and coordinates advances being
made in the operational forecasting and basic research communities.

1.1 THORPEX Objectives

THORPEX objectives are, 1) to evaluate the potential of various in situ
and remote sensing observation systems to provide the observations
needed to accelerate improvements in operational weather predictions, 2)
to evaluate model sensitivity studies and test the impact of targeted
observations by participant systems on the performance of those
operational models, and 3) to begin to acquire the observational data
needed to develop intelligent observing systems and the models and data
assimilation systems that will interact dynamically with those observing
systems.

1.2 Collaborating organizations and research groups

Collaboration is a hallmark of this TOST. Complimentary measurements are
provided by the various ground-, airborne-, and space based observing
systems participating in the campaign. These measurements provide
information that can be used directly as targeted input to operational
forecast models, as validation data for observing system evaluations or
as research data for nowcasting, forecasting and numerical model data
assimilation research.

1.  NOAA Winter Storms Research Program Overview

The purpose of the NOAA WSRP is to reduce uncertainty in 24-96 hour
forecasts for specific weather events associated with potentially large
societal impact over the continental US and Alaska by taking
supplemental adaptive observations over the northeast Pacific ocean.
These observations are based on the use of nonlinear ensemble forecasts
generated operationally on a daily basis at NCEP and ECMWF. Ensemble
members are linearly combined in such a way that their variance is
reduced at observation time over the observational area. The same linear
combination is used at verification time to see where the variance in
the transformed ensemble is reduced. All possible pre-designed flight
tracks are considered and the one where the dropsondes are expected to
reduce forecast error variance at verification time within the
verification region most is selected. As such, this highly effective
program constitutes a particularly complimentary effort to THORPEX by
directly providing a significant subset of THORPEX's overall objectives.
WSRP flight requests have to be issued 24 hours in advance of take-off
so flight planning usually takes place 36-48 hours in advance of the
actual flights. For general planning purposes, the flight facilities
also require a general outlook for the second day (i. e., whether a
flight is expected or not). To prepare such an outlook, sensitivity
calculations need to be run 60-72 hours before flight time. WSRP uses a
series of pre-selected tracks to obtain their targeted observations.
These tracks are shown in figure 1.1 below. The WSR program can be found
at: <http://wwwt.emc.ncep.noaa.gov/gmb/targobs/target/wsr2003.html> .

![](media/image1.png){width="5.998611111111111in"
height="3.9555555555555557in"}

Figure 1.1. NOAA Winter Storm Research Program Flight Tracks

2.  NASA EOS Program Objectives -- TERRA, AQUA and ICESat Validation

Aqua underflights are incorporated into the THORpex field campaign plan
to assess MODerate resolution Imaging Spectroradiometer
([MODIS](http://modis.gsfc.nasa.gov/MODIS/)) and Atmospheric Infrared
Sounder ([AIRS](http://www-airs.jpl.nasa.gov/)) L1B and L2 science
products from the [Aqua](http://aqua.nasa.gov/) satellite. MODIS and
AIRS science products including earth-atmosphere radiance, atmospheric
profiles (temperature and moisture), cloud top heights, cloud coverage
or mask, and cloud particle phase are being collected globally and
studied for signatures of Global Climate change under NASA's Earth
Science Enterprise. During the experiment, data will be collected from a
NASA high altitude (20 km) ER-2 aircraft equipped with remote sensing
instruments looking down at the earth's atmosphere and surface.
Optimally, the ER-2 will be flown underneath Aqua [(Figure
1)](http://cimss.ssec.wisc.edu/tx2002/gif/Figure1.jpg) on each ER-2
mission, collecting measurements that can be compared directly to the
MODIS and AIRS science products.

Comparisons of ER-2 based and Aqua based observations will be used to
demonstrate the accuracy of the satellite products for usage in
monitoring long term Global Climate change as well as suggest ways of
fine tuning the MODIS and AIRS science product algorithms. One of the
most important unknowns in Global Climate prediction is the percentage
and type of cloud cover over the global domain. Greenhouse gas warming
of the earth-atmosphere system is expected to increase the atmospheric
water vapor content, providing new material for the development of
clouds (2°C temperature increase translates to 10% more water vapor
holding capacity in the atmosphere). This additional water vapor may
reside as vapor in the atmosphere (a very effective heat trapping gas),
be condensed into low to mid level water droplet clouds, or be
transported in thunderstorm updrafts to cold upper tropospheric levels
where it will reside as cirrus cloud (ice particles). The physical state
of the water (gas, liquid, solid) is an important consideration as
vapor, water clouds and ice crystal clouds all have different influences
on the radiation budget. Water vapor is a highly efficient heat trapping
gas (approximately 10 times more effective than CO~2~); water clouds are
very effective sunlight reflectors and are thought to lead to a net
cooling effect on the global climate, though this is not proven. Ice
clouds meanwhile are thought to be net heat trapping clouds, as much of
the incident sunlight is transmitted and scattered downward into the
earth-atmosphere system heating the earth. MODIS and AIRS are both
designed to provide insight on global cloud and atmospheric water vapor
and temperature trends. However, before the L1B and L2 science products
can be confidently interrogated for global change signatures, the
accuracy of the science products must be demonstrated.

 

The radiometric accuracy of the recently (May 2002) launched Aqua MODIS
and AIRS instruments will be evaluated to diagnose any fine tuning of
the thermal infrared (TIR) band calibration. MODIS cloud products and
AIRS atmospheric temperature/moisture profiles from Aqua will be
evaluated.  A recent ER-2 experiment named TX-2002 (fall, 2002 based in
San Antonio, TX) was used to evaluate L2 MODIS cloud products from
Terra; THORpex extends the evaluation to Aqua. ER-2 based observations
by MAS, S-HIS, and NAST-I instruments measure upwelling TIR radiance
from the earth-atmosphere system in much the same way that MODIS and
AIRS measure the earth-atmosphere system.  The MAS instrument provides
high spatial resolution (50 m) data for revealing the MODIS 1 km
subpixel variation.  S-HIS and NAST-I provide high spectral resolution
data and excellent radiometric accuracy to which MODIS and AIRS TIR band
calibration assessments are ultimately pinned.  Together, NAST-I
(infrared) and NAST-MTS (microwave) form a complement to characterize
atmospheric temperature/moisture in clear and cloudy scenes. Dropsondes
from the NOAA G-IV aircraft will contribute to this characterization.
The CPL (lidar) measurements include cloud parameters such as cloud
height, thickness, optical depth, and cloud particle phase (ice or
liquid water); these highly accurate measurements from CPL will be
directly compared to MODIS L2 cloud products. This activity will
contribute to bridging early years of NOAA/NESDIS satellite observations
to the latter day observations of NASA\'s Terra and Aqua satellites,
extending the data record from years to decades, and facilitating the
task of uncovering Global Climate change signatures.

THORPEX is the fifth in an ongoing series of ER-2 field experiments
designed in part to assess MODIS and AIRS L1B TIR band calibration and
science products.  The WISC-T2000 (Madison, WI, March 2000), SAFARI-2000
(Pietersburg, SA, Aug/Sep. 2000), TX-2001 (San Antonio, TX, March 2001),
and TX-2002 (San Antonio, TX, November 2002) experiment data sets have
contributed to the MODIS TIR band calibration and L2 product assessment
on Terra.  THORPEX will make a new contribution to EOS product
validation by providing exclusive measurements (by advanced
instrumentation) of tropical and midlatitude cloud systems and the
atmosphere over the expansive water background of the Pacific ocean,
with it's attendant climatic characteristics, for an assessment of Aqua
MODIS and AIRS L1B and L2 science products.

Satellite validation requires precise coordination with satellite
orbital ephemerii. This is especially challenging since the target
satellites, AQUA (and TERRA) and ICESat are in opposition in ascension
and descension. This will provide for approximately six dual satellite
validation opportunities between AqQUA and ICESat during the campaign
exclusive of any WSRP considerations. It is anticipated that single
satellite validation measurements will probably be the norm and that
sufficient opportunities will exist for validation studies for both
satellites. In the event that opportunities become limited, AQUA will
have first priority, however every attempt will be made to accommodate
ICESat.

Underflights of GLAS on ICESat will be used to verify performance of the
1064 nm laser after initial turn-on about Feb 17. The 532 nm laser is
anticipated to become active on about March 1. Scenes of thick broad
cloud coverage provide good validation opportunities as these cases
minimize uncertainties associated with co-location of sensors. All
scenes are however considered useful validation targets early in the
operation of GLAS. A significant challenge of GLAS validation is to
pulse the CPL beam from the ER-2 into the narrow 120 m wide swath of
GLAS on ICESat. The Inertial Navigation System on the ER-2 is anchored
to GPS and is anticipated to be able to meet this challenge though
external forcings on the ER-2 aircraft (e.g. crosswinds, ambient
temperature fluctuations) always influence the aircraft positioning and
3-axis orientation on short timescales.

3.  IPO Objectives -- National Polar Orbiting Environmental Satellite
    System (NPOESS) Atmospheric Sounder Test-bed (NAST) Data Validation

The objectives of NAST are to, 1) simulate candidate instruments for
NPOESS: CrIS, ATMS satellites, 2) evaluate key Environmental Data
Records (EDRs) algorithms, 3) preview high-resolution
products---spectral and spatial and to 4) provide flight validation of
operational satellites. The NAST-I is a high-resolution interferometric
sounder which retrieves upwelling atmospheric radiance in the 3.6 to 17
micrometer spectral range.

The NAST-MTS is a 28 channel microwave temperature sounder that flies
with the NAST-I.

The following science measurements will be made by the NAST-I:

-   Infrared and microwave spectral radiance

-   Atmospheric thermodynamic properties

-   Surface temperature and emissivity features

-   Precipitation characteristics

-   Cloud properties: spectral radiance, phase, optical depth, and
    microphysical properties (particle size) and geometrical properties
    (height and depth)

-   Trace species (e.g. CO & O3) and aerosol amounts

-   Aviation safety meteorological parameters (associated with, e.g.,
    turbulence and icing conditions)

The following validation \[radiance, geophysical, sensor, new research
products\] objectives will be pursued:

-   Validate radiance measurements, forward radiative transfer models,
    and retrieval algorithms of existing research (e.g., Aqua
    AIRS/AMSU/HSB and Terra/Aqua MODIS) and forthcoming experimental and
    operational remote sensing systems (e.g., CrIS/ATMS and GIFTS)

-   Compare remotely sensed NAST thermodynamic state parameters, species
    amounts, and cloud and aerosol characteristics with those from
    Terra, Aqua, ICESat, and GOES and in-situ data, including drop-sonde
    observations from the NCAR drifting gondola along with dropsonde and
    in-situ ozone from the G-4 aircraft (i.e. radiometric versus in-situ
    determination)

-   Airborne sensor intercomparison: ER-2 (NAST-I, NAST-M, S-HIS, MAS,
    CPL, in-situ ozone)

-   Turbulence, icing, winds, etc. (ASAP support).

These objectives will be pursued through:

1\. Temporal & spatial coordination with NOAA G-4

> --horizontal leg overflight of high-density dropsondes across H2O
> gradient
>
> --vertical ascents/descents coincident with in-situ measurements of
> interesting O3 structure (trop. fold event, i.e. strat-trop exchange)
>
> --Remote turbulence characterization

2\. Overflight of ground-based facilities

> --Radiosondes, buoys, etc.
>
> --ER-2 racetrack pattern over UNH wind LIDAR

3\. Underflight of satellite-based sensors

> --e.g. Terra & Aqua coincident observations in clear to partly cloudy
>
> --Compare NAST-I-derived cloud & aerosol spatial distribution
> information with that from CPL and ICESat (GLAS)

4\. Overflight mapping of main island

> --Volcanic emissions (H2O, CO2, SO2, H2S)
>
> --Mauna Loa & Mauna Kea observatories (FTIR, LIDAR, GPS PW, etc.)

1.  NASA ASAP Objectives -- Aviation Weather Product Development

The objectives of ASAP are 1- to fill a critical gap in the integration
of current Geostationary Operational Environmental Satellite GOES
imagery and sounding data in the production of operational aviation
weather products that are developed by the FAA Aviation Weather Research
Program (AWRP) and 2- to bridge the gap between developing aviation
weather products using current satellite imagery and sounding data to
integrating the next generation of of high-resolution, hyperspectral
satellite data into aviation weather product development. ASAP will
fundamentally employ data obtained by the NPOESS Airborne Sounder
Test-bed (NAST) and Scanning Hyperspectral Infrared Sounder (S-HIS)
instruments, the Airborne Infrared Sounder (AIRS), the Cross-track
Infrared Sounder (CrIS) as well as Polar and Geostationary Orbiting
Environmental Satellites (POES and GOES). The goal of these efforts is
to support FAA AWRP Product Development for ground and airborne product
production and to conduct applications product demonstrations including
a NASA Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS)
AWIN demonstration in FY2007.

Since the NASA ASAP project is developing applications for hyperspectral
sounding data such as that which the NASA New Millenium Program's EO3
GIFTS Project will provide. The production of a high quality simulated
hyperspectral sounding data cube is a key ASAP objective of this
campaign. The success of the first Pacific THORPEX Operational Science
Test is particularly important to the GIFTS Project since THORPEX will
be the primary over-water validation experiment for the GIFTS satellite
during its validation year and the THORPEX program has identified GIFTS
and its operational successor, GOES-R as key observing systems. This
year's field campaign presents an opportunity to collect data for the
production of simulated GIFTS data cubes that will aid in the production
and testing of the GIFTS instrument. It is an invaluable opportunity to
develop and refine the field measurement process that will take place
during GIFTS validation.

2.  Resource summary

    1.  NOAA Gulfstream IV

The NOAA G-IV is a state of the art, high altitude research platform
with a certified ceiling of 45,000 ft (12 km), range of 4075 nm (7000
km) and true air speed of 440 kt (240 m/sec). Aircraft position and
attitude is provided by a high altitude radar altimeter, GPS-PPS
(precision positioning system) and flow angle pressure transducers.
Primary instrumentation includes a PRT-5 downward radiometer and a
C-band nose radar. Soundings of basic meteorological state parameters
(temperature, humidity and wind) are provided by the Airborne Vertical
Atmospheric Profiling System (AVAPS). Onboard data processing is
performed by two systems -- Main Aircraft Data System (MADS) or
Hurricane Analysis Processing System (HAPS). Communications equipment
include SATCOM, HF, UHF, and VHF radio communication

1.  AVAPS Dropsonde recorder and processor

The NCAR GPS Dropsonde system, also known as AVAPS (Airborne Vertical
Atmospheric Profiling System), debuted in 1997. It has flown on numerous
missions in support of operational weather forecasting and atmospheric
research. AVAPS uses dropwindsonde and Global Positioning System (GPS)
receivers to measure the atmospheric state parameters during the its
descent. Dropwindsondes measure vertical profiles of pressure,
temperature, humidity, and wind during their descent through the
atmosphere.\
 

2.  NOAA Aeronomy Laboratory

The Aeronomy Laboratory (AL) conducts fundamental research on the
chemical and physical processes of the earth\'s atmosphere,
concentrating on the lower two layers  known as the troposphere and
stratosphere. Through laboratory, modeling, and field research, AL
scientists are advancing the scientific understanding of chemical and
physical processes related to the ozone layer, the  climate system, and
air quality. The overall aim of Aeronomy Laboratory research is to
improve the capability to observe, understand, predict, and protect the
quality of the atmosphere.

2.  NASA ER-2

The ER-2 is a civilian version of the Air Force\'s U2-S reconnaisance
platform. These high-altitude aircraft are used as platforms for many
investigations that cannot be accomplished by sensor platforms of the
private sector. Aircraft and spacecraft have proven to be excellent
platforms for remote and *in situ* sensing. The ER-2, flying at the edge
of space, can profile the atmosphere very much the same way as a
satellite.

The Lockheed ER-2 was developed for the National Aeronautics and Space
Administration (NASA), to serve as a high altitude scientific research
aircraft. The ER-2 designation was first applied to NASA\'s version of
the U-2C model. NASA has since acquired and used the U2-R or TR-1 model,
but has retained the ER-2 descriptor. The ER-2 differs from the U.S. Air
Force\'s U-2 in the lack of defensive systems, absence of classified
electronics, completely different electrical wiring to support NASA
sensors, and, of course, a different paint scheme.

The ER-2 is an extremely versatile aircraft well suited to multiple
mission tasks. The ER-2 is thirty percent larger than the original U-2
with a twenty foot longer wingspan and a considerably increased payload
over the older airframe. The aircraft has four large pressurized
experiment compartments and a high capacity AC/DC electrical system,
permitting a variety of payloads to be carried on a single mission. The
modular design of the aircraft permits rapid installation or removal of
payloads to meet changing mission requirements. The ER-2 has a range
beyond 3,000 miles (4800 km); is capable of long flight duration and can
operate at altitudes above 70,000 feet (21.3 km) if required. A summary
of the aircrafts operating characteristics follows in table 1.1.

  -------------- --------------------------------------------------------
  Crew:          One Pilot

  Length:        62 feet, 1 inch

  Wingspan:      103 feet, 4 inches

  Engine:        One Pratt & Whitney J75-P-13B

  Altitude:      70,000 feet

  Range:         2200 nautical miles, 3000 on exception

  Duration:      6.5 hours, 8 hours on exception

  Cruise Speed:  \~400 knots above 65,000 feet altitude \~210 meters/sec
  -------------- --------------------------------------------------------

Table 1.1. ER-2 Characteristics

During the three weeks of THORPEX, the ER-2 will fly approximately ten
missions in the 0 - 40latitude belt of the central Pacific Ocean. The
ER-2 payload will consist of the MODIS Airborne Simulator (MAS), the
Scanning High-resolution Interferometer Sounder (S-HIS), the NPOESS
Atmospheric Sounder Testbed -- Interferometer (NAST-I) and -- Microwave
Temperature Sounder (NAST-MTS), the Cloud Physics Lidar (CPL) and a fast
in situ ozone probe.

![](media/image2.png){width="4.20625in" height="4.20625in"}

Figure 1.2 MODIS 250 m 013101

1.  MODIS Airborne Simulator

The MODIS Airborne Simulator (MAS) is a 50 channel (VNIR -- TIR)
airborne scanning spectrometer that acquires high spatial resolution
imagery of cloud and surface features from its vantage point on-board a
NASA ER-2 high-altitude research aircraft. MAS collects 50 m (nadir)
spatial resolution data across a 37 km swath (+/- 43 view angle) from
the nominal ER-2 20 km altitude. MAS uses dichroics and four gratings to
separate upwelling earth scene radiance into VNIR (9 channels: 0.47 --
0.96 m), SWIR (16 channels: 1.6 -- 2.4 m), MWIR (16 channels: 3.1 -- 5.3
m) and LWIR (9 channels: 8.5 -- 14.2 m) spectral regions.

MAS reflectance channels (VNIR, SWIR) are calibrated using laboratory
measurements collected from a calibrated integrating sphere at NASA Ames
Research Center (ARC) both before and after aircraft deployments. These
measurements are supplemented by ground-based measurements collected
during pre-flight of each ER-2 mission. Thermal IR channels (MWIR, LWIR)
are calibrated using two flat plate onboard blackbody sources, one of
which is typically heated to about 20C, the other being allowed to
settle to ambient conditions at altitude in the scan cavity of the MAS
scan assembly. Blackbody emissivity is characterized periodically in a
laboratory setting to maintain performance. The onboard blackbodies are
viewed on each scan line; an additional view upward into the MAS scan
head is used to characterize background radiance in the scan cavity for
use in the L1B calibration algorithm. MAS TIR band radiometric
calibration accuracy is about 0.5 to 1.0C depending on channel (best in
window bands); however, MAS accuracy can be improved to within 0.5C
through comparisons to co-incident S-HIS and NAST-I observations. MAS
reflectance channel calibration accuracy is conservatively estimated to
be within 10%.

MAS is spectrally calibrated before deployments at the NASA ARC facility
using both monochromator-based and FTIR-based measurements. The four
gratings are each aligned to specific spectral positions. These
measurements are repeated at ARC after the ER-2 deployment to confirm
that the spectral characterization has not changed during the
deployment.

Data acquired by the MAS have been a key element in defining,
developing, and testing science product algorithms for the Moderate
Resolution Imaging Spectroradiometer (MODIS), a key sensor of NASA\'s
Earth Observing System (EOS). MAS continues to function as a validation
tool in complement with the S-HIS, NAST-I, and CPL instruments for MODIS
and AIRS L1B and L2 science products. The MODIS and AIRS programs
emphasize the use of remotely sensed data to monitor variation in
environmental conditions for assessing both natural and human-induced
global change.

2.  Scanning High-resolution Interferometer Sounder

The Scanning High-resolution Interferometer Sounder (S-HIS) is a
scanning interferometer which measures emitted thermal radiation at high
(0.5 cm^-1^) spectral resolution between 3.3 and 18 microns
(specifications).  The measured emitted radiance is used to obtain
temperature and water vapor profiles of the Earth\'s atmosphere.  S-HIS
produces sounding data with 2 kilometer resolution (at nadir) across a
30 kilometer ground swath (+/- 35 view angle) from a nominal altitude of
20 kilometers onboard a NASA ER-2 aircraft or 15 kilometer ground swath
from a nominal altitude of 10 kilometers aboard the NASA DC-8 aircraft. 

The S-HIS radiometric accuracy is a key component of its usage in
validating science products from MODIS and AIRS. S-HIS is calibrated in
flight using two onboard high emissivity (.996, known to within .001)
cavities with temperature knowledge to better than 0.1 K. The S-HIS
in-flight reference cavities have been characterized using National
Institute of Standards and Technology (NIST) traceable standards. The
S-HIS scene mirror surface is gold coated to minimize reflectance
variation and polarization as a function of scan angle. The performance
of S-HIS has been routinely tested in the laboratory environment to
ensure ongoing high accuracy radiances during in-flight data collection.
These tests include component characterization as well as system testing
such as data collection over ice baths, and side by side comparisons
with other interferometers. A typical radiometric uncertainty of the
S-HIS observations using the estimated uncertainty of S-HIS cavity
performance (i.e. 0.1 K for cavity temperature, 0.001 for cavity
emissivity) during in-flight data collection conditions is less than 0.2
K for atmospheric window regions and less than 0.3 K for atmospheric
absorption regions (some exceptions for saturation on strong absorption
lines).

3.  NPOESS Atmospheric Sounder Testbed

The National Polar-orbiting Operational Environmental Satellite System
(NPOESS) Aircraft Sounder Testbed -- Interferometer (NAST-I) is a high
resolution Michelson interferometer, developed at MIT Lincoln
Laboratory, that derives its heritage from the non-scanning High
resolution Interferometer Sounder (HIS) developed by researchers at the
University of Wisconsin. The NAST-I instrument scans the earth from
beneath the ER-2 with a nominal spatial resolution of approximately 2.5
km with a total of 13 earth views in the cross-track direction (the
resultant swath width covers about 45 km). The unapodized spectral
resolution of NAST-I is 0.25 1/cm within a 590-2810 1/cm (3.6-17 micron)
spectral range. The instrument flies in the right superpod of NASA\'s
high altitude ER-2 research aircraft. The infrared radiance measurements
obtained from the NAST-I instrument will provide detailed spectral
characteristics of the atmosphere and land surface along with providing
detailed atmospheric temperature and water vapor profiles derived from
either physical or regression based retrieval algorithms.

The National Polar-orbiting Operational Environmental Satellite System
(NPOESS) Aircraft Sounder Testbed- Microwave Temperature Sounder
(NAST-MTS) is an aircraft-mounted Microwave Temperature Sounder. The
instrument, built by Massachusetts Institute of Technology\'s Research
Laboratory of Electonics (RLE), is about the size of a footlocker, and
is mounted inside the forward section of one of the wing mounted
\'superpods\' of the NASA ER-2 aircraft. NAST-MTS is a scanning
radiometer which sweeps from side to side viewing a path that is sixty
five degrees either side of nadir. MTS covers 16 microwave frequencies
in the vicinity of  54 gigahertz and 118 gigahertz in each of its scans.
This results in an image that is approximately 80 kilometers wide
measured from the aircraft altitude (\~20km). The radiometer \'sees\' in
the microwave portion of the elecromagnetic spectum. Images produced by
the instrument represent the thermal radiation emitted by the
environment at these microwave frequencies. Each microwave frequency
responds differently to temperatures at different altitudes as well as
to the different constituents such as water vapor, precipitation and
ice. By combining the information gathered from MTS with information
derived from the sensors in both the visible and infrared regions of the
spectrum, the structure and composition of the atmosphere in the field
of view as well as surface characteristics may be determined. Since
microwave frequencies penetrate clouds much more readily than do
infrared or visible, internal structure becomes apparent. By measuring
the location, intensity

4.  Cloud Physics Lidar

The Cloud Physics Lidar (successor to the [Cloud Lidar
System](http://virl.gsfc.nasa.gov/er2cls.html)) is an airborne lidar
system designed specifically for studying clouds and aerosols using the
NASA ER-2 aircraft. Because the ER-2 typically flies at 65,000 feet (20
km), its instruments are above 94% of the earth\'s atmosphere, thereby
allowing ER-2 instruments to function as spaceborne instrument
simulators. The Cloud Physics Lidar provides a unique tool for
atmospheric profiling and is sufficiently small and low cost to include
in multiple instrument missions.

The Cloud Physics Lidar provides a complete battery of cloud physics
information. Data products include:

-   Cloud profiling with 30 m vertical and 200 m horizontal resolution
    at 1064 nm, 532 nm, and 355 nm, providing cloud location and
    internal backscatter structure.

-   Aerosol, boundary layer, and smoke plume profiling at all three
    wavelengths.

-   Depolarization ratio to determine the phase (e.g., ice or water) of
    clouds using the 1064 nm output.

-   Cloud particle size determined from a multiple field-of-view
    measurement using the 532 nm output (off-nadir multiple scattering
    detection).

-   Direct determination of the optical depth of cirrus clouds (up to
    \~OD 3) using the 355 nm output.

The CPL provides information to permit a comprehensive analysis of
radiative and optical properties of optically thin clouds. To determine
the effects of particulate layers on the radiative budget of the
earth-atmosphere system certain information about the details of the
layer and its constituents is required

1.  Langley In Situ Fast-Response Ozone Measurements

The In Situ Fast-Response Ozone sensor is capable of fast, sensitive
ozone measurements over a large dynamic range and a wide variety of
atmospheric conditions. The measurements are performed by combining pure
reagent nitric oxide (NO) with incoming sample air in a small volume
reaction chamber, and by measuring the resulting chemiluminescence. This
chemiluminescence is light emitted in the near-infrared spectral region
by relaxation of nitrogen dioxide (NO2) that has been excited by the
chemical reaction of NO and ozone (O~3~) in the sample. The chemical
equations for this set of reactions are:

(1) NO + O~3~ O~2~ + NO~2~\*

```{=html}
<!-- -->
```
(1) NO~2~\* NO~2~ + hn

This technique is very well established \[Pearson and Stedman, 1980,
Gregory et al., 1987, Eastman and Stedman, 1997\] and is a reverse
application of a standard nitric oxide (NO) detection technique \[Clough
and Thrush, 1967\]. The near-infrared light emitted by relaxation of the
excited NO~2~ (chemiluminescense) is measured with a sensitive
photocathode and photomultiplier tube (PMT). The amplified signal from
the PMT is proportional to the amount of O~3~ in the sampled air.

The reaction chamber is maintained at constant temperature and pressure
(17 Torr) and sampled air enters the aircraft through a forward-facing,
J-shaped probe. Sample flow from the prechamber into the reaction
chamber is 500 cm^3^/minute. We maintain a laboratory reference O~3~
photometer that is regularly taken to NIST for intercomparison with
their standard O~3~ photometer. The residual between the NIST-referenced
linear regression and our O~3~ measurements in the laboratory is 1 ppbv
or less over the range of our measurements.

  ----------------- -----------------------------------------------------
  Technique         Chemiluminescent Reaction of Ozone with Nitric Oxide

  Dynamic Range     0.5 -- 3500 ppbv

  Accuracy          5 percent or 5 ppbv

  Precision         3 percent pr 2.5 ppbv

  Response Time     2-3 Hz

  Data Rate         1 Hz

  Spatial           \~200 m horizontal (vertical -- depends on ascent
  Resolution        rate)

  Weight            260 lbs

  Power Required    Less than 10 A 110V/60 Hz
  ----------------- -----------------------------------------------------

Table 1.2 Ozone Instrument Specifications

1.  NCAR ATD Driftsonde System

The engineering activities associated with the driftsonde development
have focused on developing the onboard electronics, a communication
system for sending instructions to the driftsonde and transmitting data
back to earth, design of the gondola, design of the balloon and
associated safety systems (transponder, parachute, and the method for
balloon cut-down). The first test of the driftsonde balloon,
electronics, and communication system took place on February 28^th^ 2002
from the balloon manufacturer's facility (GSSL) in Tillamook, Oregon.
This first test flight was very successful and verified proper operation
of the onboard computer system, sensor system, ballast control system,
battery power system, partial verification of the satellite
communication system, and confirmation of the passive thermal control of
the electronics. There were no dropsondes launched during this first
test. Complete system testing, including the dropping of sondes took
place with two short duration flights (48 hour) in the fall of 2002
(October/November) and early 2003 (January) from the balloon
manufacture's facility in Tillamook, Oregon. At the completion of these
tests the system completed prototype testing and is underwent final
modifications prior to the 2003 Pacific TOST. These tests included the
first attempt at developing the operational procedures for balloon
inflation and launch as well as onboard dropsonde data processing, data
communication through the satellite to a ground station and placement of
the data on the Global Telecommunications System (GTS).

The driftsonde system objectives for the 2003 Pacific TOST are to
further explore the overall utility of observing system within the
context of the THORPEX program and to assess its utility in satellite
data validation and applications efforts being conducted by NASA, who is
sponsoring the driftsonde deployment. The TOST will employ two
driftsonde systems to drop GPS dropsondes over the Pacific Ocean. The
two driftsonde flights over the Pacific Ocean from the GSSL launch
facility in Hawaii will be coordinated with proof of concept test
flights with airborne remote and in situ sensors and dropsondes as
scientific tools for the refinement of driftsonde operations. The
deployment is for two gondolas and 40 dropsondes total (20-per flight).
ATD technical staff and two staff members from GSSL will go to Hawaii to
run the launch and monitor the system to help reduce the chance of
failure and to continue the development of the operational launch
techniques. The following is a list of the key activities associated
with the 2003 Pacific TOST driftsonde operation.

-   RTF and two GSSL technical staff will go to Hawaii to assemble and
    launch the driftsonde balloon systems.

-   RTF data management and engineering staff will monitor the flight
    and process the data.

-   The data will be inserted into the GTS in near-real-time and
    provided to the PI.

-   A 10 day operational period will be conducted coinciding with PTOST
    to launch two gondolas.

-   20 sondes per balloon flight will be dropped

-   The Driftsondes will be launched from the GSSL facility on the Big
    Island of Hawaii (South Point) during early March.

![](media/image3.jpeg){width="5.597916666666666in"
height="7.471527777777778in"}

Figure 1.3

Driftsonde and Payload Prior to Launch in November 2002

![](media/image4.png){width="5.0in" height="3.4923611111111112in"}

Figure 1.4

Sounding from November 2002 Driftsonde Test

![](media/image5.png){width="4.8493055555555555in"
height="3.732638888888889in"}

Figure 1.5

70 mb Average Winds for the Northern Pacific February 15^th^ to March
15^th^ 2002

1.  Mauna Loa Groundwinds LIDAR

The GroundWinds Hawaii (GWHI) lidar is a groundbased molecular Doppler
lidar located on Mauna Loa in Hawaii. During operation, the instrument
continuously measures the velocity of the air in the direction parallel
to an outgoing laser beam. The laser beam is oriented at a 45 degree
vertical angle, relative to the ground, and can scan horizontally over
approximately a 300 degree range. The instrument can be used to deduce
an average three-dimensional velocity field by scanning. The vertical
resolution and a temporal integration can both be adjusted prior to
operation.

The overarching goal of the GroundWinds progam is to develop and
demonstrate incoherent ultra-violet lidar technology for a future based
system that will measure the vertical structure of global winds from
molecular backscatter. Successful retrievals of zonal winds profiles
form the Hawaii facility have been obtained to altitudes greater than 20
km and ranges near 30 km.

This UV Lidar can measure altitude resolved line-of-sight wind
velocities, turbulence power spectra, areosol content and faint cirrus
clouds among other things of interest to the astronomers of the nearby
Mauna Kea Observatories.

Data from the incoherent LIDAR are used in a custom forecasting project
[(Mauna Kea Weather Center)](http://hokukea.soest.hawaii.edu/) that
provides operational support for the world-class group of astronomical
observatories located on the summit of Mauna Kea.

2.  Other Surface Data

Other sources of surface met data include:

1.  Mauna Kea and Mauna Loa Observatories (big island)

2.  Mees Solar Observatory (Maui)

3.  Hilo (big island) and Lihue (Kauai) Radiosondes

4.  Ground-based FTIR from Mauna Loa

5.  Buoy data

    a.  NDBC: air and sea temperature, wind speed and direction, air
        pressure, and wave period, height, and spectra

    b.  USACE: wave info

    c.  SCDIP: Sea temperature, wave info

    d.  

    e.  

> ![](media/image6.png){width="4.5152777777777775in"
> height="3.9131944444444446in"}

Figure 1.6 Drifting Buoy Stations

2.  Deployment and Operations Schedule

    1.  The following is a schedule of major campaign dates:

Feb 15 Langley Team departs Norfolk VA

Feb 16 Check out offices in hangars for aircraft and instrument teams

Feb 17 Set up offices and conduct comm checks with participating
facilities

Feb 18 ER-2 arrive Hickam.

Feb 19 Down-day. Hazmat (dimethylhydrazine fuel) briefing to Hickam Fire
Dept.

Daily Operations Schedule Begins

Feb 20 First available measurement flight day

Mar 12 Last available measurement flight day and THORPEX departure day

Mar 13 WSRP deployment ends

#### Chapter 2. 2003 Pacific TOST Operations

####  

2.  Introduction

Daily Pacific TOST operations will be coordinated from Hickam AFB,
Building 2055. Morning weather briefings and daily planning meetings
will also be conducted there. ER-2 base operations will be in building
1045, where pre-flight and post-flight briefings will be held.
Additional office space for the NAST team, other THORPEX participants
and NOAA G-4 flight crews and scientists is located at the Air Service
Hawaii FBO.

2.1 Primary functional areas and responsibilities

2.1.1 TOST Operations Coordinator and Deputy Operations Coordinator

The 2003 Pacific THORPEX Operational Science Test Coordinator is John
Murray of the NASA Langley Research Center ( <j.j.murray@larc.nasa.gov>

, (757) 329-4484). The Deputy Operations coordinator is Chris Moeller of
the University of Wisconsin (<chris.moeller@ssec.wisc.edu> , [(608)
263-7494]{.underline}).

2.1.2 NOAA NCEP Winter Storms Research Program

The WSRP is directed by Dr. Zoltan Toth of the NOAA NCEP Environmental
Modelling Center (<Zoltan.Toth@noaa>.gov, (301) 763-8000/ext. 7268). It
is staffed 24/7 by the Senior Duty Meteorologist who can be reached for
operational coordination at <Sdm@noaa>.gov, 301-763-8298 (or
301-763-8000/ext. 7361). Administrative issues between THORPEX and the
WSRP can be coordinated with Lacey Holland (<Lacey.Holland@noaa>.gov).

2.1.3 Aircraft Coordinators

2.1.3.1 The NASA ER-2 Mission Manager is Jeanette Vandenbosch of the
NASA Dryden Flight Research Center
(<jeannette_vandenbosch@dfrc>.nasa.gov, (661) 816-9516.

2.1.3.2 The NOAA Gulfstream IV coordinator for THORPEX is the Flight
Director of the NOAA AOC, Jack Parrish (<jackparrishwx@netscape>.net).
Daily G-IV operations will be coordinated through the WSRP G-IV project
manager, beginning with Mark Finke ((813) 833-2405).

2.1.4 Instrument Coordinators

2.1.4.1 The NAST Instrument PI is Bill Smith of the NASA Langley
Research Center (<william.l.smith@larc>.nasa.gov, (757) 897-9597. The
NAST Manager is Allen Royal (<A.C.Royal@larc>.nasa.gov, (757) 864-7927).

2.1.4.2 The Scanning HIS Instrument PI and manager is Hank Revercomb of
the University of Wisconsin (<hankr@ssec.wisc.edu>, 608-263-6758) and
MODIS Airborne Simulator Instrument PI is Chris Moeller (for Michael
King) of the University of Wisconsin (chris.moeller@ssec.wisc.edu,
[(608) 263-7494]{.underline}). MAS is managed by Jeff Myers of NASA Ames
Research Center (<jmyers@mail.arc.nasa.gov>, (650) 604-6252)

2.1.4.3 The Cloud Physics LIDAR Instrument PI is Matthew McGill of the
NASA Goddard Space Flight Center (<Matthew.J.McGill@nasa>.gov, (301)
614-6281).

2.1.4.4 The In Situ Fast Ozone Detector Instrument PI is Melody Avery of
the NASA Langley Research Center (<m.a.avery@larc>.nasa.gov, (757)
864-5522).

2.1.5 The operational Driftsonde Coordinator is David Parsons, the
Director NCAR ATD (<parsons@atd>.ucar.edu, (303). Administrative
coordination should be addmatters may be addressed to Melinda Finch
Cagle at the NASA Langley Research Center (<m.f.cagle@larc>.nasa.gov,
(757) 864-7211).

2.1.6 The Mauna Loa Groundwinds LIDAR Coordinator is John McHugh of the
University of New Hampshire (<jpm@cisunix>.unh.edu, (603) 862-1899). The
Techincal Support coordinator is Ivan Dors, UNH,
<idors@comptel.sr.unh.edu>

, (603) 862-2867. The U. Hawaii POC is Steve Businger,
<businger@hawaii.edu> , (808) 956-2569. The Hawaii field coordinator is
Tiziana Cherubini, U. Hawaii, <tiziana@hawaii.edu> , (808) 956-4593.
Additional points of contact are James Foster, U. Hawaii,
<jfoster@soest.hawaii.edu> , (808) 956-4593

and Ryan Lyman, U. Hawaii, <rlyman@hawaii.edu> , (808) 956-4593

2.1.7 The 2003 THORPEX OST Satellite Support Coordinator is Louis Nguyen
of the NASA Langley Research Center (<l.nguyen@larc>.nasa.gov, (757)
864-9066).

2.2 Other TOST Facilities

2.2.1 Hickam AFB

2.2.1.1 2003 Pacific TOST Operations Center, Building 2055, Hickam AFB,
HI

2.2.1.2 Hickam AFB, HI ER-2 Support Facilities

2.2.1.3 ER-2 Operations, Building 1045, Hickam AFB, HI

2.2.1.4 ER-2 Hangar, Hangar 35, Hickam AFB, HI

2.2.2 Air Services Hawaii, 95 Nakalo Place, Honolulu, HI, (800)
821-3122.

2.2.2.1 NOAA Gulfstream IV, Mark Finke, Project Manager, (813) 833-2405.

2.2.2.2 NAST Instrument Team and Project Scientists,

2.2.3 National Weather Service Honolulu Forecast Office, 2525 Correa Rd,
Ste 250, Honolulu, HI 96822,
<http://www.prh.noaa.gov/pr/hnl/index.shtml>

2.2.4 Naval Pacific METOC Center

2.2.5 GSSL Balloon Launch Facility

2.2.6 Mauna Kea Growndwinds LIDAR Site

2.3 Daily Mission Planning Process and Schedule

Coordination with the NOAA Winter Storms Research Program (WSRP) will
drive the daily mission planning process. TOST mission planning will
begin each afternoon after notification by the NOAA G-IV Project Manager
or flight crew as to whether the next day has been tasked by NCEP as a
WSRP flight day..The NOAA Gulfstream IV aircraft's primary tasking is in
support Of the WSRP. On WSRP fly days the TOST will have the option to
operate (fully or partially) in conjunction with the scheduled WSRP
flight track or to operate independently. NCEP's WSRP tasking is
received from CARCAH in Miami by 8:30 a.m. HI local time (13:30 EST) for
the next day's work. The standard NOAA aircraft launch time is 20Z (10
a.m. HI local time) +/- one half hour. Flight duration is from 6.5 to 8
hours for the Gulfstream IV aircraft the same as for the NASA ER-2.

A TOST operations meeting will normally be held daily at 3 p.m. in
building 2055, Hickam AFB. To accomodate participation by those at the
Air Services Hawaii TOST Office and elsewhere, a telcon connection will
be provided to the meeting.

  ----------------------------------- -----------------------------------
  Announcements                       TOST coordinator, deputy,
                                      participants

  Current Synoptic situation          NOAA or NASA duty forecaster

  Aircraft and instrument status      A/C mission managers, instrument
  reports                             PI's

  Today's TOST mission status         TOST coordinator or deputy

  WSRP flight decision -- next        G-IV manager or representative
  day/outlook                         

  24 hour forecast                    NOAA or NASA duty forecaster

  TOST objectives and options         Directed discussion

                                      

                                      

                                      
  ----------------------------------- -----------------------------------

Table 2.1 Daily TOST planning meeting agenda

2.3.1 Daily TOST Operations Schedule

Daily TOST operations will be posted on the campaign website the evening
before. Generally, the elements of each day's operations are summarized
in table 2.2. Specifically, the execution of each element of the mission
and the relevant flight tracks and instrument operating modes and
special procedures will be posted on the website.

+---------------------------+------------------------------------------+
| ER-2 launch time --4      | > Morning weather brief and go/no-go     |
| hours                     | > decision                               |
|                           | >                                        |
| ER-2 launch time --3      | > ER-2 pre-flight brief                  |
| hours                     | >                                        |
|                           | > Hands off ER-2 aircraft                |
| ER-2 launch time --2      | >                                        |
| hours                     | > NOAA G-IV WSRP launch time             |
|                           | >                                        |
| 10:00 A.M +/- ½ hour      | > Daily TOSToperations planning brief    |
|                           | >                                        |
| 3:00 P.M.                 | > NOAA G-IV WSRP landing time            |
|                           | >                                        |
| 5:00 P.M. +/- ½ hour      | > ER-2 landing time                      |
|                           | >                                        |
| ER-2 launch time + 4-7    | > ER-2 post-flight brief                 |
| hours                     | >                                        |
|                           | > To be scheduled                        |
| ER-2 shut down time + ½   | >                                        |
| hour                      | > As required                            |
|                           |                                          |
| TOST Science Meetings     |                                          |
|                           |                                          |
| Evening updates           |                                          |
+---------------------------+------------------------------------------+

Table 2.2 Daily TOST Operations Summary

2.4 Air Operations

2.4.1 NOAA Gulfstream IV

2.4.2 NASA ER-2

#### 2.4.2.1 Pre-flight Operations 

There are three general limitations to ER-2 operations:

1.  Routine flight duration for the ER-2 is six and one half hours.
    Flights longer than six and one half hours require specific,
    compelling justification. If no alternative presents itself to
    accomplish the mission objectives (such as flying two sorties
    instead of one) a longer duration flight of seven to eight hours can
    be flown with specific approvals. Such flights may be approved by
    the mission manager or the branch chief of The High Altitude Branch.
    Sustained operations of this nature can quickly deplete crew
    resources and are therefore best avoided.

2.  An ER-2 pilot is limited to twelve hours duty time. Duty time begins
    at pre-flight reporting and ends at engine shutdown.

3.  ER-2 pilots and maintenance crews must have at least twelve hours of
    off-duty time between leaving the flight line after one flight and
    reporting back for the next flight.

Once a mission has been assigned on the previous day, the ground crew,
pilots, and investigators meet three hours before the scheduled take off
time. At this meeting, available weather information is reviewed, the
investigators brief the pilots on the desired mission objectives, and
the status of the aircraft and its instruments is reviewed. If the
weather permits, and the investigators feel that there is a reasonable
chance of meeting their science objectives, the preparation for a flight
begins. Each instrument team, and the aircraft ground crew, begins their
pre-flight inspections and preparations, while the aircraft is still
inside the hangar. Aircraft systems and instruments are tested, and the
ejection seat and related life support hardware are installed in the
cockpit. Access to the ER-2 at Hickam AFB, Hangar 35 will be restricted
to instrument technicians and PI's who are directly servicing their
instruments.

Approximately two hours prior to flight the aircraft is towed from the
hangar and fueled. During this operation, no electrical power will be
available to the aircraft. For safety reasons, personnel whose tasks are
not connected with this operation will not be allowed near the aircraft
at this time. When fueling and oxygen replenishment are completed,
external power will be connected to the aircraft (approximately one hour
prior to launch). In order to prevent possible damage from voltage
transients, the instruments will normally be shut off while external
power is removed and internal power is selected. If continuous power is
necessary for a particular instrument, arrangements must be made well in
advance.

About one hour prior to flight, the mission pilot [suits
up](http://www.dfrc.nasa.gov/Research/AirSci/ER-2/pshis.html#Why) and
begins pre-breathing pure oxygen, to purge nitrogen from his
bloodstream. Since the pressure suit worn by the mission pilot restricts
mobility and makes pre-flight checks difficult, the mobile pilot
inspects the aircraft approximately one hour prior to launch. With the
pre-flight checks completed, the mission pilot will be driven to the
aircraft in a support van approximately 30 minutes prior to scheduled
launch.

The engine is started approximately fifteen minutes prior to launch.
Once the pilot is disconnected from the ground oxygen supply, and the
canopy is closed, heat will build rapidly in the pilot\'s pressure suit.
For this reason the aircraft is taxied to the runway as soon as possible
following post engine start-up checks.

2.4.2.2 Launch procedures

The ER-2\'s long, flexible wings are supported during ground taxi and
takeoff by auxiliary wheels, called \"pogos\". These wheels, as well as
the main gear, are locked in place during taxi. The mobile pilot and the
ground crew accompanies the aircraft to the active runway in a van or
jeep. This vehicle is equipped with radios to talk to both the airfield
tower operators and the ER-2 pilot. Once the ER-2 has taxied onto the
active runway in position for launch, the ground crew pulls the locking
pins for the pogos and main gear. During the takeoff roll, when the
ER-2\'s wings develop enough lift to flex upward, the pogos drop to the
runway below. The ground crew recovers the pogos and returns to the
hangar. The pogos can usually be used hundreds of times before needing
to be replaced, although they must be carefully inspected for damage
after each takeoff. To minimize the impact of the ER-2\'s flight profile
on Air Traffic Control, the ER-2 strives to launch on time.

3.  Aircraft scientific crews and instrument technicians

Except for pre-flight and post-flight briefings, access to the Hickam
AFP ER-2 Hangar will be limited to designated technicians and PI's.
Pre-flight and post flight briefings in building 1045 will accomodate
additional personnel as permitted.

2.4.4 Flight patterns

2.4.4.1 NOAA WSRP flight patterns

The 2003 Pacific TOST will conduct joint WSRP missions in which the NASA
ER-2 will overfly the NOAA G-IV on a standard WSRP flight track as
illustrated in figure 1.1. During these missions, the ER-2 may deviate
from the WSRP track for short periods of time to conduct measurements
for satellite validation or other purposes.

2.4.4.2 EOS/IPO Satellite validation patterns

Coincident MODIS and NAST-I observations are important form enabling
cloud studies for CrIS IFOV. Since a small window of opportunity may
exist for the validation of satellite data each day, every opportunity
will be made to accommodate it. Normally, the validation of a polar
orbiting satellite will entail a transit to an anticipated nadir point
and transit along the orbital axis in one or both directions depending
upon the size of the satellite's footprint. In the event that there is
more than one satellite of interest, such as AQUA and ICESat (GLAS)
which are moving in opposition, timing will be especially important.

Underflights of EOS satellites (Aqua, ICESat) will be planned to allow
the ER-2 to align itself along the orbital track approximately 10-15
minutes prior to satellite arrival, and continue along the track until
about 10-15 minutes after satellite overpass, maintaining straight and
level flight through the duration (exception of any maneuvers necessary
to reverse direction). For GLAS validation, nadir underflights are
required to collect co-incident CPL and GLAS observations in the GLAS
120 m wide swath. For Aqua underflights, both nadir and off-nadir
underflights (parallel to the satellite orbital track) are sought for
MODIS and AIRS science product validation.

2.4.4.3 ASAP and GIFTS data cube production patterns

2.2.4.3.1 Regional mapping presents the best opportunity to construct
simulated GIFTS data cubes.For regional mapping it is often useful to
operate the ER-2 in a pattern of 4 parallel flight lines oriented
perpendicular to isoheights so that the gradient on each flight line can
be seen. At the completion of the 4 lines, the pattern is typically
re-flown in the same sequence so that the time offset of repeat pass for
each line is approximately the same. This helps clarify temporal
influences. Each run of a 4-line pattern typically takes 60 to 75
minutes depending on the flight line length (12 minute leg covers \~150
km along track), so two runs typically requires 2.25 to 2.75 hrs on
site. The pattern is typically held to to 4-lines because it keeps the
time offset from 1st pass to 2nd pass to about 75 minutes. In the across
track direction, 4 parallel lines translate to about 150 km of
contiguous coverage for MAS. For NAST-I and S-HIS it would be desirable
to tighten the spacing of the flight lines to get contiguous coverage,
especially when flying over a solid undercast which effectively reduces
cross-track coverage by a factor related to the altitude of the cloud
deck.

High density dropsonde observations from the NOAA G-IV would be highly
desirable during regional mapping operations. The G-4 would be flown at
maximum altitude (45kft) below the ER-2 flight track. Dropsondes
observations would be distributed regularly throughout the 2 -- 3 hour
observation period.

2.4.4.4 ASAP Phenomenological Targeting (Turbulence, Icing, Convection,
Ceiling and Visibility and Volcanic Ash).

ASAP objectives will be best met with a robust GIFTS data cube (2x2,
3x3, or even 3x4) simulation that covers areas possessing a range of
weather. Aircraft in this TOST have to be flexible enough to fly in the
vicinity of jet exit and entrance regions, as well as near mesoscale jet
streaks, for the detection of turbulence. One possible set of flight
paths should parallel the main polar jet with the ER-2 as it lies across
the Pacific north of Hawaii. Concurrently, the NOAA G-4 would collect
dropsondes by crisscrossing the jet axis at various altitudes to obtain
profiles in and around the jet. Since the can jet meander significantly,
it is very difficult to locate and to precalculate flight legs and/or
flight distances.

Another option for the detection of CAT is to enhance flight profiles
performed previously by the NOAA Gulfstream IV in SCAT-CAT missions by
overlying the G-4 with an ER-2 grid of downward looking radiometric
profiles and in situ ozone measurements to attempt to dept the
propagation of inertial gravity wave-breaking associated with CAT. See
<http://www-frd.fsl.noaa.gov/mab/scatcat> .

Other ASAP flight profiles may be southward of HI to overfly deep
convection. All other convection over the Pacific will be shallow and
associated with post-cold frontal advections of arctic air over the
north Pacific south of Alaska. This is not a primary option since the
convective storm objectives for ASAP are much better met by the IHOP
data sets that are already starting to show great promise.

ASAP clouds and cloud microphysics objectives (e.g., icing, ceiling and
visibility), will be satisfied if the EOS validation objectives are
satisfied. Volcanic ash and gas detection validation opportunities
exploiting MODIS and AVHRR split window techniques should be pursued
wherever possible. Volcanic activity will be targeted by the ER-2 after
takeoff and prior to landing whenever possible.

2.5 Driftsonde Coordination

2.5.1 Honolulu GSSL launch coordination

2.5.1.1 Honolulu ARTCC coordination

2.5.1.2 Notification procedures

2.5.1.3 Tracking and data provision requirements

2.6 Mauna Loa Groundwinds LIDAR Coordination

University of Hawaii personnel will be provided administrative space at
the Air Services Hawaii facility to coordinate Groundwinds LIDAR
operations with the THORPEX OST.

The tentative Operating Plan is for GWHI to provide the horizontal wind
field, and for direct comparison with other airborne and driftsonde
measurements. The GWHI instrument will be operated in a manner to
optimize the data quality for average winds. This means a temporal
integration time of 60 seconds, and a vertical resolution of 80 meters.
The horizontal scan will include five angles, separated by 30 degrees.
The resulting wind measurement is an average of these five angles. The
instrument will record data for 30 minutes at each angle, making the
duration of an entire scan 150 minutes. Variations on this scheme are
possible, including a narrower field of view, shorter record length at
each angle, and more or less angles for a given scan. Final data
analysis can be performed with fewer angles than were recorded.

The operating plan for GWHI will be to take data during the daytime
operating hours for the NOAA G4 and ER2 aircraft during the entire
campaign. During the first days of the driftsonde, GWHI may additionally
collect data at night. The final operating decisions will be made during
the campaign, and will depend on weather, the availability of personnel,
and other matters.

2.7 Data distribution Policy

THORPEX does not currently provide for centralized archiving of TOST
data. Individual PI's are responsible for the archiving and appropriate
distribution of the data obtained from their instruments and science
teams.

Access to data files from the THORPEX OST Website and participant sites
and experiments is controlled to protect the experiment PI\'s and others
with rights to the data. All data obtained by individual PI's
participating in the first Pacific THORPEX Operational Science Test will
be freely shared among them, however,this does not imply permission for
distribution to third parties. Requests from third parties should be
referred to the individual instrument PI.

Use of any images and/or THORPEX data from participating websites and
field experiments must be made with the authorization of the
instrument's PI. An offer of co-authorship on any publications,
presentations, etc. must be made to the PI and his/her team if images
and/or data are used (even if they are freely accessed).

2.7.1 Science quicklooks

Science quicklooks will be made available on the 2003 Pacific TOST
website on a daily basis. This will be facilitated via links to websites
maintained by the various instrument PI's participating in the campaign.

### Chapter 3. 2003 Pacific TOST Links

**2003 PTOST** <http://www-angler.larc.nasa.gov/thorpex/>

##### THORPEX [**http://www.mmm.ucar.edu/uswrp/thorpex/thorpex_plan13.pdf**](http://www.mmm.ucar.edu/uswrp/thorpex/thorpex_plan13.pdf)

### NASA [**http://www.nasa.gov**](http://www.nasa.gov/)

NASA DFRC

NASA GSFC

NASA LaRC

##### NOAA [**http://www.noaa.gov**](http://www.noaa.gov/)

Aeronomy Lab <http://www.al.noaa.gov/>

WSRP <http://wwwt.emc.ncep.noaa.gov/gmb/targobs/target/wsr2003.html>

RECON <http://www.nhc.noaa.gov/reconlist.shtml>

THORPEX
<http://wwwt.emc.ncep.noaa.gov/gmb/ens/NOAA_THORPEX_INITIATIVE.ppt>

NCEP Ensemble Forecasting
<http://wwwt.emc.ncep.noaa.gov/gmb/ens/canadaworkshop.ppt>

##### Aircraft

ER-2 <http://www.dfrc.nasa.gov/Research/AirSci/ER-2/fltops.html>

G4 <http://www.aoml.noaa.gov/hrd/jetgen.html>

##### Observing Systems

AVAPS <http://www.vaisala.com/DynaGen_Attachments/Att2688/2688.pdf>

MAS <http://mas.arc.nasa.gov/>

CPL <http://virl.gsfc.nasa.gov/cpl/>

S-HIS <http://deluge.ssec.wisc.edu/~shis/>

NAST-I,M
<http://spigot.ssec.wisc.edu/~nasti/NASTI/ins_overview/overview.html>

Driftsonde <http://www.atd.ucar.edu/rtf/facilities/icaruss/icaruss.html>

Groundwinds Lidar <http://www.groundwinds.com/>

##### Satellites and Satellite Sensors

AQUA/TERRA

AIRS

MODIS

ICESat

EO3/GIFTS