**Composition of the Atmosphere from Mid-Earth Orbit\
(CAMEO)**

![](media/image1.png){width="3.310416666666667in"
height="7.372916666666667in"}

> CAMEO is a future mission concept submitted May 2005 to the U.S.
> National Research Council Decadal Survey on *Earth Science and
> Applications from Space.*
>
> This update of CAMEO merges the Atmospheric Remote-sensing and Imaging
> Emission Spectrometer (ARIES) concept also submitted May 2005 to the
> Decadal Survey.
>
> by
>
> Joe Waters, Moustafa Chahine, Nathaniel Livesey,\
> Thomas Pagano, Michelle Santee, Hartmut Auman,\
> Paul Stek, Qinbin Li, Duane Waliser,\
> Annmarie Eldering, Michael Gunson, et al.
>
> **NASA Jet Propulsion Laboratory,\
> California Institute of Technology, USA**
>
> Pieternel Levelt, Hennie Kelder, Bert van den Oord,\
> Pepijn Veefkind, Ilse Aben, Avri Selig
>
> **Royal Netherlands Meteorological Institute and\
> National Institute for Space Research, The Netherlands**
>
> Mitch Goldberg and Chris Barnet
>
> **NOAA National Environmental Satellite,\
> Data, and Information Service, USA**
>
> John Le Marshall
>
> **NOAA/NASA/DoD Joint Center\
> for Satellite Data Assimilation, USA**
>
> Bob Atlas
>
> **NOAA Atlantic Oceanography and\
> Meteorological Laboratory , USA**
>
> Joel Susskind
>
> **NASA Goddard Space Flight Center, USA**
>
> Larrabee Strow and Wallace McMillan
>
> **University of Maryland Baltimore County, USA**
>
> Bob Harwood and Hugh Pumphrey
>
> **The University of Edinburgh,
> Scotland**![](media/image2.wmf){width="0.9777777777777777in"
> height="0.21875in"}
>
> [very incomplete draft]{.underline}

#  

[1. Summary 3](#summary)

[2. Contributions to Earth Science and Applications
6](#contributions-to-earth-science-and-applications)

[2.1 Human Health and Security 6](#human-health-and-security)

[2.1.1 Air Quality 6](#air-quality)

[2.1.2 UV Exposure 10](#uv-exposure)

[2.2 Climate Variability and Change 12](#climate-variability-and-change)

[2.3 Water Resources and the Global Hydological Cycle
15](#water-resources-and-the-global-hydological-cycle)

[2.4 Weather (including space weather and chemical weather)
16](#weather-including-space-weather-and-chemical-weather)

[2.5 Earth Science Applications and Societal Needs
18](#earth-science-applications-and-societal-needs)

[2.5.1 Transition of research to operations
18](#transition-of-research-to-operations)

[2.5.2 Support of policy decisions for well-being of life and
environmental sustainability
18](#support-of-policy-decisions-for-well-being-of-life-and-environmental-sustainability)

[2.5.3 Information to decrease society's vulnerability to envionmental
variability
18](#information-to-decrease-societys-vulnerability-to-envionmental-variability)

[3. Instruments 19](#instruments)

[3.1 Tropospheric Pollution Imager (TROPI)
19](#tropospheric-pollution-imager-tropi)

[3.2 Atmospheric Remote-sensing and Imaging Spectrometer (ARIES)
20](#atmospheric-remote-sensing-and-imaging-spectrometer-aries)

[3.2.1 ARIES Observational Variables 20](#aries-observational-variables)

[3.2.2 ARIES Product Accuracies 20](#aries-product-accuracies)

[3.2.3 ARIES Instrument Requirements 22](#aries-instrument-requirements)

[3.2.4 ARIES Instrument Concept 23](#aries-instrument-concept)

[3.3 Scanning Microwave Limb Sounder (SMLS)
24](#scanning-microwave-limb-sounder-smls)

[4. Launch vehicle and satellite bus
26](#launch-vehicle-and-satellite-bus)

[5. Operations 26](#operations)

[6. Data processing 27](#data-processing)

[Appendices 28](#appendices)

[A1. Comparing coverage for CAMEO and TRAQ orbits, and with two
satellites
29](#a1.-comparing-coverage-for-cameo-and-traq-orbits-and-with-two-satellites)

[A2. CAMEO 'measurement traceability'
31](#a2.-cameo-measurement-traceability)

[A3. Currently-planned future satellite instruments
31](#a3.-currently-planned-future-satellite-instruments)

[A4. ARIES instrument details 31](#a4.-aries-instrument-details)

[A5. TROPI instrument details 31](#a5.-tropi-instrument-details)

[A6. SMLS instrument details 31](#a6.-smls-instrument-details)

[A7: Orbital Environment 31](#a7-orbital-environment)

[A8. Simulation results (e.g., SMLS upper trop retrieval simulations)
31](#a8.-simulation-results-e.g.-smls-upper-trop-retrieval-simulations)

[A9. Risk Mitigation (Do we want this? It was asked for by NRC RFI)
31](#a9.-risk-mitigation-do-we-want-this-it-was-asked-for-by-nrc-rfi)

[A?: Others? 31](#a-others)

[References 32](#references)

# 1. Summary 

Human activities are changing atmospheric composition in ways that can
adversely affect life on Earth. Unhealthful urban pollution episodes are
common and increasing pollution, especially from China and India, can
affect global air quality and, possibly, the atmosphere's ability to
cleanse itself. Increasing greenhouse gases and aerosols, and pollution
lofted into the upper troposphere, can affect climate. Stratospheric
chlorine loading is now more than 5× the natural amount, with the
potential for more severe ozone depletion before chlorine decreases to
near-natural abundances in \~50 years.

Crucial policy decisions related to atmospheric composition -- involving
balances between economic and environmental concerns -- must be made,
but obtaining the necessary consensus is politically difficult. Existing
regulations on ozone depleting substances demonstrate that consensus on
such issues can be obtained if sufficiently-complete scientific
information is produced and clearly explained. This requires global
measurements of atmospheric composition.

CAMEO gives global composition measurements needed to enable informed
policy decisions related to air quality and climate change. For example,
it quantifies episodic emissions of pollution worldwide and tracks
pollution transport across national boundaries and around the globe --
essential to supporting international policy to improve and protect
regional and global air quality. It globally measures the diurnal cycle
of convective deposition of water vapor and pollution into the upper
troposphere -- essential for quantifying water vapor feedback and
pollution effects on climate.

CAMEO remedies measurement deficiencies, especially in temporal
resolution, that have inhibited progress in science and applications
directly linked to societal needs and benefits by providing:

a)  a greatly-improved combination of temporal and spatial resolution
    for key air quality, climate change, and hydrological cycle
    measurements needed simultaneously with global coverage,[^1]

b)  new upper tropospheric measurements needed to quantify how changes
    in air quality may affect climate,

c)  measurements of cloud ice and water vapor with temporal, vertical
    and horizontal resolution needed to improve understanding of the
    hydrological cycle[^2] and the accuracy of GCMs used for weather and
    climate prediction,[^3] and

d)  post-Aura measurements needed to develop an operational forecast
    model to predict changes in UV dosage in the coming decades, and for
    warning of changes in ozone layer stability well before they are
    evident in ozone itself.[^4]

CAMEO − a logical follow-on to Aura − uses a mid-Earth orbit, new for
composition measurements, and advanced technology in three proven
instrument types:

(1) **ARIES**, the **A**tmospheric **R**emote-sensing and **I**maging
    **E**mission **S**pectrometer, an advanced version of AIRS on Aqua,
    measures infrared thermal emission from 3.5 to 15μm wavelengths.
    Major improvements of ARIES are (a) 1×1 km horizontal resolution
    (15× improvement over AIRS) and (b) improved spectral resolution.
    Both are needed for middle and lower tropospheric composition
    measurements;

(2) **SMLS**, the **S**canning **M**icrowave **L**imb **S**ounder, an
    advanced version of MLS on Aura, measures millimeter and
    submillimeter emission in two broad spectral bands centered at 240
    and 640 GHz. Major improvements of SMLS are (a) simultaneously
    scanning the limb in both horizontal and vertical directions to
    provide 50×50 km horizontal resolution (50× improvement in
    cross-track resolution, 3× in along-track, over Aura MLS) and 1-2 km
    vertical resolution needed for upper tropospheric measurements
    and (b) in-orbit programmability for rapid response to changing
    priorities;

(3) **TROPI**, the **TRO**pospheric **P**ollution **I**mager, an
    advanced version of OMI on Aura with long heritage from SCIAMACHY
    and TOMS, measures reflected/backscattered solar radiation in UV,
    visible, and near/shortwave infrared. Major improvements are (a)
    bands in the near and short-wavelength infrared to give CO and CH~4~
    in the boundary layer and (b) new detectors/gratings that give the
    OMI-demonstrated 10×10 km resolution from CAMEO's orbit. Additional
    studies will determine if better than 10 km resolution is feasible
    and cost-effective.

These broad-swath instruments having multiple successive orbit overlaps
(see cover figure) provide an unprecedented combination of
temporal/spatial resolution and global coverage needed to quantify fast
processes that affect air quality and climate, and improve models used
for weather/climate predictions. Launch vehicles used for polar
sun-synchronous low-Earth orbit can insert CAMEO directly into the
desired orbit.

![](media/image3.png){width="6.820833333333334in"
height="2.5965277777777778in"}

**Fig. 1**. Temporal and global coverage of CAMEO measurements.
[Everywhere]{.underline} within a given color is measured that number of
times per 24-hour period. Measurements are made in 'spurts' of \~2 hour
intervals (approximately the orbit period) followed by a gap of several
hours. During every season the temporal measurement pattern precesses
through all local times. SMLS and ARIES measurements (thermal emission)
have a frequency pattern that is nearly constant throughout the year and
is shown in the bottom panels. The TROPI measurements (reflected and
backscattered sunlight) have a frequency pattern that varies annually as
shown in the upper rightmost panel: mid-latitudes are measured 4-5 times
per day over month-long periods that switch between northern and
southern hemispheres. Two CAMEOs flying in formation can fill in the
mid-latitude gaps shown here (see Appendix A1). The top left and top
center panels show the TROPI measurement frequency in May (peak time of
Asian pollution transport to America) and August (peak time of urban
pollution in the U.S. and Europe).

Figure 1 quantifies CAMEO's temporal and global coverage for the
baseline 1500-km, 52^o^ inclination circular orbit. This 1.9 hour period
orbit is selected as a good compromise between higher orbits that are
more difficult to implement (and have longer orbital periods with
reduced temporal resolution) and lower orbits that have poorer global
coverage. The inclination, and right ascension of the ascending node,
are chosen to favor measurements in the summer hemisphere (for air
quality issues), to give year-round SMLS measurements to ±82^o^ latitude
on each orbit, and to have a coverage pattern that repeats annually.

Figure 2 shows the suite of CAMEO atmospheric measurements.

**Fig 2**. CAMEO atmospheric measurements (dashed lines are goals). The
break in the horizontal line separating middle and lower troposphere for
N~2~O and HNO~3~ indicates that only a column for the combined middle
and lower troposphere is obtained for these species. SMLS measurements
of HO~2~, O~3~, HCN, NO, NO~2~, HCl, and BrO extend into the mesosphere.

The CAMEO measurements were chosen in to fill priority needs in the
following areas

-   **Air quality.** CAMEO makes all the priority tropospheric
    measurements (O~3~, CO, NO~2~, H~2~CO, SO~2~, aerosols) identified
    by the February 2006 "Community Workshop on Air Quality Remote
    Sensing from Space: Defining an Optimum Observing Strategy" and the
    NRC Decadal Study Panel on Human Health and Security.

-   **UV exposure.** CAMEO makes all the priority chemical measurements
    (O~3~, H~2~O, HO~2~, NO~2~, ClO, BrO, HNO~3~, HCl, H~2~CO, HDO,
    H~2~^18^O, CO~2~, CO, NO~Y~, N~2~O, CH~4~) -- except for OH (for
    which HO2 is a proxy), IO (which cannot currently be done from
    space), and halogen source molecules (which can adequately be
    measured by other techniques and platforms)[^5]. It's additional
    measurements of H~2~O~2~, NO, HOCl, CH~3~Cl, and volcanic SO~2~
    provide additional measurements to help track stability of the ozone
    layer.

-   **Climate variability and change.** Sentence(s) to be added
    here[^6].

-   **Water resources and the global hydrological cycle.** Sentence(s)
    to be added here.

-   **Weather.** Sentence(s) to be added here, if we can make sufficient
    case.

Appendix A2 gives the 'measurement traceability' for the CAMEO
measurements. The CAMEO measurements fill an important gap not covered
by other planned satellite instruments (see Appendix A3).

The three CAMEO instruments work together to obtain the important, but
often difficult, lower tropospheric measurements. With CO and O~3~, for
example, SMLS gives well-defined columns for the upper troposphere and
above, yielding a constraint for ARIES and TROPI retrievals that
sharpens their vertical resolution. The different middle and lower
tropospheric sensitivities of ARIES and TROPI then yield separate middle
and lower tropospheric CO and O~3~ abundances. This reads too 'lame' --
need to make it stronger.

TROPI tropospheric column measurement accuracy is several percent for
CH~4~, 10-20% for O~3~, NO~2~ and CO, and \~50% for CH~2~O and SO~2~,
depending on atmospheric conditions; we anticipate this can be improved
for some gases (e.g., O~3~) by combining TROPI and SMLS data. Preceding
from original CAMEO document -- needs to be reworked and sentences on
cloud and aerosol added.

ARIES Material to be added.

SMLS measures stratospheric profiles and columns with a few percent
precision and accuracy, and temperature profiles with 0.1K precision and
\~1K accuracy. The SMLS upper tropospheric precision is addressed later
in Figure ?. An important feature of SMLS is its ability to make upper
tropospheric measurements in the presence of ice clouds. SMLS also
quantifies the ice water content of upper tropospheric clouds, and gives
information on whether the characteristic ice particle size for the
cloud is larger or smaller than \~30 μm.

NOAA's Satellite Meteorology and Climatology Division has encouraged
NASA to develop the CAMEO capability for NOAA's operational use of CAMEO
data.

With TROPI proposed to be developed by the Netherlands and with proposed
strong UK participation, CAMEO implements the international cooperation
advocated by the July 2003 Earth Observation Summit. Add more, if/when
ESA announces that TRAQ has been selected for further study.

# 2. Contributions to Earth Science and Applications

CAMEO addresses 5 of the 7 panel areas organized by the NRC Earth
Science and Applications from Space decadal study:

1.  Human Health and Security

2.  Climate Variability and Change

3.  Water Resources and the Global Hydrological Cycle

4.  Weather (including space weather and chemical weather)

5.  Earth Science Applications and Societal Needs

The contributions in each of these areas are discussed in the following
subsections.

## 2.1 Human Health and Security {#human-health-and-security .unnumbered}

### 2.1.1 Air Quality {#air-quality .unnumbered}

Air quality -- locally, regionally and globally -- is a major concern.
Over 120 million US citizens live in areas that do not meet air quality
standards for at least one of EPA's"criteria" pollutants \[reference?\].
All major cities in the world suffer air quality problems. Figure 3
shows Aura's OMI (precursor of CAMEO's TROPI) measurements of
tropospheric NO~2~ pollution for the month of October 2004. It is
estimated that air pollution contributes to tens of thousands of
premature deaths in the US, and hundreds of thousands of premature
deaths worldwide \[reference?\]. While local and regional emissions
sources are the main cause of air pollution problems, there is
increasing evidence that many pollutants are transported on a
hemispheric or global scale. These flows may be important for
understanding northern hemisphere air pollution problems in urban areas,
and background levels in rural areas, but their quantification remains
highly uncertain.

![](media/image4.wmf){width="3.454724409448819in"
height="1.9846456692913386in"}![](media/image4.wmf){width="3.539763779527559in"
height="0.4200787401574803in"}![](media/image5.jpeg){width="2.530708661417323in"
height="2.247244094488189in"}

Over the next ten years, NOAA and EPA \[add similar statement on
European (and Chinese/India?) agencies?\] plan to provide daily ozone
and particulate matter guidance forecasts based on combining
ground-based data with data from the NOAA NPOESS and GOES-R satellites
\[reference?\]. It is generally agreed[^7] that to achieve these
ambitious operational forecast goals, the priority air quality
measurements are tropospheric O~3~, CO, NO~2~, HCHO, SO~2~ and aerosols
and that such measurements need be taken with high spatial (\< 10 km)
and temporal (\< 4 hr) resolution. CAMEO provides all these priority
measurements, and complements geostationary Earth orbit by giving the
needed global coverage and vertical resolution.

CAMEO will producedirect-broadcast and near-real-time data that can be
used in operational air quality forecasts, in addition to producing data
files archived and publicly available for scientific research,.

Figure 4 shows the importance of CAMEO's temporal and spatial
resolution. This shows NO~2~ pollution in the southeastern United States
between 1 and 7 pm for a day in August 2000, as given by the EPA CMAQ
regional pollution model. The model has been sampled at the 2-hour
temporal resolution of CAMEO, and at its 10 km spatial resolution for
NO~2~. Aura, for example, measures only near 1:30 pm local time − as
shown in Figure 3 − and misses the much larger abundances of NO~2~
pollution that occur later in the day. The demonstrated ability of
Aura's OMI to measure the smaller midday NO~2~ abundances ensure that
the larger pollution occurring later in the day will easily be measured
by TROPI on CAMEO.

![](media/image6.png){width="1.6653543307086613in"
height="1.095275590551181in"}![](media/image7.png){width="1.6838582677165355in"
height="1.094488188976378in"}![](media/image8.png){width="1.6736220472440946in"
height="1.0964566929133859in"}![](media/image9.png){width="1.6763779527559055in"
height="1.0992125984251968in"}

In addition to NO~2~, CAMEO measures several other tropospheric
pollutants at this resolution. Figure 5 shows the diurnal and day-to-day
variations of the urban pollutants measured by CAMEO, and fine
particulate matter. The very substantial temporal variations, both
diurnally and day-to-day -- emphasize, again, the importance of CAMEO's
temporal resolution.

Figure 6 shows the demonstrated OMI capability to measure tropospheric
SO2 pollution from urban and industrial (and volcanic) sources. CAMEO
will have the same capability, but with much improved temporal
resolution to measured diurnal and day-to-day variations as exemplified
in Figure 5.

![](media/image10.jpeg){width="1.2799212598425196in"
height="1.8574803149606298in"}![](media/image11.jpeg){width="1.345275590551181in"
height="1.8464566929133859in"}![](media/image12.jpeg){width="1.3228346456692914in"
height="1.956299212598425in"}![](media/image13.jpeg){width="1.3929133858267717in"
height="1.699212598425197in"}![](media/image14.jpeg){width="0.42559055118110234in"
height="9.015748031496063e-2in"}

The combined temporal, horizontal and resolution - and global coverage -
of CAMEO is essential to assess the contributions of regional and
sub-regional pollution to the global atmosphere, as well as the
influence of global changes on regional pollution. How is a nation's air
quality affected by pollution arising beyond its region of control? A
widely-cited study \[Jacob et al., *GRL*, 1999\] shows how rising Asian
emissions can impact air quality in the U.S. Figure 7 are AIRS
measuremens of middle tropospheric CO, indicating showing transport of
pollution from Asia to America. The improved spectral resolution of
ARIES yields better mid-tropospheric CO data than can be produced by
AIRS, approaching the quality of TES CO data, and the improved temporal
resolution of CAMEO will allow detailed tracking of pollution worldwide.

![](media/image15.png){width="2.9263779527559057in"
height="1.7708661417322835in"}

SMLS will quantify pollution transport in the upper tropsphere. Figure 8
shows Aura MLS measurements of upper tropospheric CO during the peak
period of transport of Asian pollution to the Americas, compared with
output from the GEOS-CHEM near-real-time model. The
dramatically-improved SMLS spatial resolution, over that of Aura MLS,
will allow hitherto unforeseen upper tropospheric transport phenomena to
be directly observed. Figure 9 compares high-resolution model CO fields
as would be seen by Aura MLS and by CAMEO SMLS. Among many features
evident from CAMEO, but not from Aura, is the thin filament connecting
enhanced CO above the Americas to Asian CO pollution.

![](media/image16.wmf){width="2.961023622047244in"
height="1.2244094488188977in"}![](media/image16.wmf){width="2.961023622047244in"
height="1.252755905511811in"}

![](media/image17.png){width="1.9755905511811023in"
height="1.3562992125984252in"}![](media/image18.png){width="1.9653543307086614in"
height="1.3562992125984252in"}

CAMEO gives detailed and continuous tracking of the long-range transport
of pollution around the globe -- essential international policy for
protecting and improving global air quality.

There is evidence that northern hemisphere tropospheric O~3~ abundances
have increased several-fold since pre-industrial times. This increase
has been linked to industrial emissions of the O~3~ precursors CH~4~,
CO, NO~x~, and volatile organic compounds (VOCs), but the specific
contributions are not well quantified. Through its chemical impact on
OH, the O~3~ increase may be affecting the oxidizing capacity of the
atmosphere. Changes in the oxidizing capacity would have wide-ranging
implications for future global air quality, aerosol formation,
greenhouse radiative forcing, and stratospheric ozone layer stability.
CAMEO's multiple daily measurements of tropospheric O~3~, CH~4~, CO,
NO~2~, and CH~2~O as a proxy for VOCs, provide data needed to quantify
affects on global ozone. The vertical resolution of CAMEO is
particularly important in this regards, allowing details of transport
between the troposphere and stratosphere, so that the effects of
downward transport of ozone-rich air from the stratosphere can be
removed from potential anthropogenic effects. Figure 10 shows the global
distribution of tropospheric ozone, obtained from differencing Aura OMI
measured total column and Aura MLS measured stratospheric column. CAMEO
will continue these important measurements, needed long-term to quantify
global changes in tropospheric ozone.

![](media/image19.jpeg){width="0.8216535433070866in"
height="6.456692913385827e-2in"}

### 2.1.2 UV Exposure  {#uv-exposure .unnumbered}

Ultraviolet (UV) radiation is lethal to life on Earth, causing DNA
damage to all life forms. The stratospheric ozone layer, which developed
along with life, protects us from exposure to solar UV. It has been
estimated, for example, that a 5% reduction in stratospheric ozone would
cause an annual increase in the U.S. alone of \~70,000 skin cancer cases
for which the fatality rate is approximately 1 death in 100 cases
\[National Research Council, 1982\]. The amount of ozone in the
stratosphere is set by a delicate dynamic equilibrium between production
and loss. Ozone is continuously produced by solar radiation from
breaking down molecular oxygen in a process that, globally, involves
\~2x10^13^ W of solar energy (about 3x the total power consumption of
humankind, including the heating of buildings) \[Hunten, 1977\]. But
ozone in concentrated form is a violent explosive, releasing almost the
same amount of energy as the same mass of TNT \[Hunten, 1977\]. This
energetically-difficult production of ozone, coupled with the ease by
which it can convert to other forms, is the fundamental reason for the
potential instability of the ozone layer. Chemicals introduced by human
activity can have the potential to destroy ozone - catalytically, so
that a relative small amount of certain chemicals can have a large
effect on ozone.

Efforts over the past 3 decades by scientists, government and industry
are rightfully recognized as tremendously successful in regards to
safeguarding our ozone layer without damaging our economy. However, we
should not let this success lead to complacency -- and remember that the
threads leading to discovery of the CFC threat to ozone were tenuous:
Lovelock's curiosity in using his new electron capture detector for
measuring CFCs on a British ship bound for the Antarctic; the fortuity
of his presenting the results at a conference attended by Rowland;
Rowland and Molina's curiosity in pondering the ultimate fate of CFCs
released into the atmosphere. Even after 10 years of intense research to
understand chlorine destruction of stratospheric O~3~, its most
spectacular manifestation -- the Antarctic ozone hole discovered through
Farman's careful measurements and analyses -- completely shocked the
community of scientists working this issue. Although CFC production has
been curtailed, the stratosphere will be loaded with chlorine for at
least the next few decades. As stratospheric O~3~ can be destroyed
through many catalytic cycles influenced by human activity, we should
not take the stability of the ozone layer for granted. The historical
examples mentioned here teach us the necessity of continued careful
measurements.

CAMEO provides the needed critical measurements to monitor ozone layer
stability and give early warnings of changes. In addition to O~3~
itself, SMLS measures both the dominant chlorine reservoir (HCl) and
reactive radical (ClO) involved in stratospheric O~3~ depletion, which
give crucial information on whether chlorine partitioning is changing
with changing climate (e.g., a cooler stratosphere would cause more
chlorine to be in the O~3~-destroying ClO form). SMLS measurements of
temperature, HNO~3~, H~2~O, ClO, HCl (and possibly TROPI measurements of
aerosol extinction by thick polar stratospheric clouds) provide
additional information on microphysical processes that can trigger
increased O~3~ destruction. Figure 10 shows Aura MLS measurements made
with coarse resolution. The better SMLS resolution, and temperature
precision of 0.1 K, provide needed new insights into these complicated
and extremely temperature-dependent processes. The long-lived tracers
N~2~O, CO (and, in many situations, H~2~O and O~3~) give information on
dynamics and transport. These, along with temperature, diagnose
tropopause structure and other dynamical effects that strongly influence
column ozone. The high-resolution SMLS data will enable progress in
stratospheric and upper tropospheric dynamics that was planned for

![](media/image21.png){width="4.207638888888889in"
height="2.9868055555555557in"}

Aura but lost due to a HIRDLS mishap. Their new temporal resolution, in
addition, will help quantify the extent to which fast convective
processes might be transporting short-lived ozone-depleting substances
into the stratosphere. HCl in the upper stratosphere is a measure of
total chlorine loading and thus a crucial test of international
regulations to reduce stratospheric chlorine; CAMEO continues the
long-term global HCl measurements from UARS and Aura. Figure 12 shows
the time series of Aura MLS measurements to date of halogen species in
the stratosphere. The observed decrease in HCl is consistent with the
rate at which anthropogenic chlorine is expected to be cleansed from the
stratosphere \[Froidevaux et al., 2006\]. Although this cleansing will
take more than 50 years, Aura MLS can track it with useful accuracy on a
seasonal basis -- and SMLS onCAMEO will have \~30x better sensitivity to
HCl than Aura. BrO is both the dominant form of bromine in the
stratosphere and the dominant form of bromine that destroys O~3~. There
are still regulatory issues regarding certain bromine compounds, and the
BrO measurement provides information needed for policy decisions
balancing economic and environmental concerns. H~2~O, HO~2~, and
H~2~O~2~ monitor hydrogen chemistry, and N~2~O, HNO~3~, NO~2~, and NO
monitor nitrogen chemistry -- both important for tracking ozone layer
stability. The very broad spectral programmability of SMLS (section 3.3)
gives a capability for measuring additional gases should the need arise.
The SMLS ability to measure trace gases in dense volcanic aerosol,
demonstrated on UARS following the Pinatubo eruption, is key to
quantifying the effects of volcanic eruptions on the ozone layer.

TROPI continues the very accurate long-term and high-resolution
measurements of column ozone.

![](media/image22.png){width="1.7625984251968505in"
height="1.361023622047244in"}

## 2.2 Climate Variability and Change {#climate-variability-and-change .unnumbered}

Following material excerpted from original CAMEO document, and needs to
be rewritten.

In addition to its importance for global air quality, quantifying the
processes that affect upper tropospheric O~3~ is crucial for reducing
uncertainties in predictions of climate change. The increase in
tropospheric O~3~ since pre-industrial times is estimated \[Prather,
*IPCC*, 2001\] to give the third-largest increase in direct radiative
forcing of climate. It is in the upper troposphere that the effect of
O~3~ is largest. CAMEO provides information on the processes affecting
upper tropospheric and lower stratospheric O~3~ to a degree not
previously possible, especially the fast convective processes that
deposit boundary layer gases into the upper troposphere, where they can
directly perturb O~3~ chemistry. TROPI measurements of CH~4~, an
important greenhouse gas, also give information for climate change.

![](media/image23.jpeg){width="2.366535433070866in"
height="1.4716535433070865in"}The CAMEO suite of measurements and
spatial/temporal resolution will diagnose how anthropogenic aerosols
affect upper tropospheric cloudiness, a key question in regards to
climate change and transport of H~2~O into the stratosphere. Fig. 5
shows MLS observations of correlations in enhanced upper tropospheric
clouds and uplifted pollution. Has anthropogenic aerosol pollution
contributed to the observed enhancement in clouds? This question is
starting to be addressed with Aura data, but much better resolution
microwave measurements, as provided by SMLS, are needed. Its ability to
distinguish between 'large' and 'small' crystal clouds gives important
diagnostics. The measurements of aerosol properties are essential for
addressing pollution effects on clouds. Fig. 8 shows examples of aerosol
measurements of the type TROPI will make several times daily over both
land and sea. These measurements distinguish between reflecting and
absorbing aerosols, as needed to improve climate models. The improved
SMLS resolution, compared to MLS on Aura, greatly facilitates the
combined analyses of microwave and UV/Vis/SWIR data.

![](media/image24.jpeg){width="3.5846456692913384in"
height="1.9437007874015748in"}![](media/image25.jpeg){width="2.395275590551181in"
height="1.6956692913385827in"}~2~O in the upper troposphere. Upper
tropospheric H~2~O can either amplify or attenuate the climatic effects
of increases in other greenhouse gases, depending upon the process
affecting it and the spatial and temporal scales of the process.
Measurement of upper tropospheric H~2~O has historically been very
difficult − due both to its relatively small abundance and to the
presence of ice clouds that degrade or prevent its measurement by many
techniques. Microwave limb sounding, however, is well-suited to this
measurement because of its combination of good vertical resolution,
sensitivity and long wavelengths that can measure both gas phase
abundances in the presence of ice clouds and the larger ice amounts that
saturate or block shorter wavelength techniques. (Scattering is
inversely proportional to the 4^th^ power of wavelength: small particles
affect 1 mm wavelength microwaves 10^8^ times less than 10 µm infrared.)
UARS MLS demonstrated the ability to measure upper tropospheric H~2~O,
and the left panel of Fig. 9 gives an example of results showing the
effects of El Niño on upper tropospheric H~2~O. The improved temporal
and spatial resolution of SMLS on CAMEO, and its measurements of
H~2~^18^O and HDO (which yield additional information on condensation
processes) -- neither of which are available from Aura MLS -- are needed
to understand crucial details of processes affecting upper tropospheric
H~2~O and its influence on climate variability.

![](media/image26.png){width="4.361805555555556in"
height="1.8659722222222221in"}

![](media/image27.png){width="3.2862204724409447in"
height="0.3964566929133858in"}![](media/image28.png){width="3.155511811023622in"
height="2.186220472440945in"}CAMEO provides a needed new capability for
determining the role of fast processes (e.g., deep convection) in
linking regional pollution, global air quality and climate change.
Quantifying biogenic emissions of VOCs is crucial for understanding
tropospheric radical chemistry that affects air quality. Strong biogenic
emissions of the VOC isoprene (C~5~H~8~) cause enhanced formaldehyde
(CH~2~O) to form over southeastern U.S. in summer, for example, as
measured by UV/Vis technique from space and modeled as shown in Fig. 6.
CH~2~O is an excellent proxy for VOC emissions. TROPI measures CH~2~O in
the lower troposphere − aided by subtraction of SMLS upper tropospheric
CH~2~O column. The TROPI observations of CH~2~O, NO~2~ and aerosol can
be used in conjunction with inversions of chemical transport models to
quantify these emissions. During summer, when VOC emissions peak, there
is also frequent deep convection that deposits enhanced CH~2~O directly
into the upper troposphere as shown in Fig. 6. This CH~2~O can be the
primary source of HO~x~ that regulates upper tropospheric O~3~
production, especially in the tropics and subtropics. SMLS will, for the
first time, quantify injections of CH~2~O and other boundary-layer gases
into the upper troposphere, as well as the lower stratosphere. (UARS MLS
detected CH~3~CN, from a forest fire, injected into the lower
stratosphere \[Livesey et al., *JGR,* 2004\].)

SMLS measures many upper tropospheric species, as shown in Fig. 7.
Measurement of this suite of species, which exhibit a wide range of
chemical lifetimes and solubilities, with the CAMEO temporal and spatial
resolution will give a needed first 'climatology' of the extent to which
the upper troposphere is directly affected by the boundary layer. The
lower height limit of measurements is set by H~2~O and dry air
'continuum' attenuation. Radiance data from UARS MLS over a 5-year
period indicate that SMLS typically will measure tropospheric trace
species down to\
9 km, H~2~O to 7 km, and temperature to 5 km. Measurements extend lower
in dry situations; they generally can be made where H~2~O abundances are
\< \~1000 ppmv.

**Candidate figures to be added to climate change section**

![](media/image29.png){width="3.1688976377952756in"
height="1.1838582677165355in"}![](media/image30.jpeg){width="1.6366141732283463in"
height="1.0708661417322836in"}![](media/image31.png){width="1.7236220472440944in"
height="1.0480314960629922in"}![](media/image32.png){width="2.255511811023622in"
height="0.7082677165354331in"}![](media/image32.png){width="2.2374015748031497in"
height="0.7444881889763779in"}

![](media/image34.png){width="2.8263779527559056in"
height="0.8826771653543307in"}![](media/image34.png){width="2.8263779527559056in"
height="0.8661417322834646in"}![](media/image35.png){width="0.9346456692913386in"
height="0.10433070866141732in"}

![](media/image36.png){width="2.5771653543307087in" height="2.75in"}

##   {#section-1 .unnumbered}

##  {#section-2 .unnumbered}

## 2.3 Water Resources and the Global Hydological Cycle {#water-resources-and-the-global-hydological-cycle .unnumbered}

**To be added -- someone other than JWW needs to provide draft of this,
including figures.**

## 2.4 Weather (including space weather and chemical weather) {#weather-including-space-weather-and-chemical-weather .unnumbered}

**Following, a placeholder for now, is from a section of the May 2005
document entitled 'Weather and Climate Modeling'. This needs to be
rewritten, and**

![](media/image38.png){width="3.055511811023622in"
height="3.038976377952756in"}*Weather and Climate Modeling*

One of the most significant shortcomings in current weather and climate
models is the representation of clouds and their feedbacks on the global
water and energy cycles. This shortcoming includes both convective and
non-convective clouds, applies to both GCMs and regional models, and
impacts both weather and climate predictions. The accurate depiction of
clouds and related hydrological processes in the upper troposphere is
essential for predicting climate change. It is in the upper troposphere
that water vapor feedbacks are most acute and cloud feedbacks − in this
case from deep convective and high cirrus/ice clouds − are undeniably
significant. Aura MLS has demonstrated simultaneous observations of
cloud ice and relative humidity, as shown in Fig. 9, which are important
for understanding cloud formation. The ability to produce
height-resolved maps of cloud ice (as is the case for all SMLS
measurements) is shown in Fig. 10. The bulk alignment of cirrus crystals
has also been measured from polarization of the MLS signals \[C. Davis
et al., *GRL*, in review\]. SMLS provides the improvements (see Fig. 2)
over UARS and Aura MLS in temporal and horizontal resolution that are
needed to understand the 'fast' convective processes affecting clouds
and the hydrological cycle in the upper troposphere.

Fig. 11 compares cloud ice from MLS, ECMWF analyses, and
state-of-the-art GCMs. Considerable discrepancies in the amount and
spatial variability of cloud ice are apparent in the GCM results.
Reducing these uncertainties is crucial for improving both weather and
seasonal climate (e.g., monsoon, ENSO) forecasts, and decreasing the
uncertainties in long-term climate change. The MLS capability to provide
these crucial measurements has been demonstrated, but better resolution
is needed to fully exploit their impact on weather and climate models.
CAMEO gives the needed improvement and produces unprecedented data for
(1) model development and tuning, particularly in regards to cloud
microphysical parameterizations, (2) augmenting initial conditions for
weather forecasting, including rapidly evolving severe weather
conditions, and (3) improving regional and global climate records
through re-analysis.

![](media/image39.png){width="6.686614173228347in"
height="2.3279527559055118in"}

![](media/image40.png){width="4.52007874015748in"
height="2.1736220472440944in"}CAMEO provides a new resource for
examining the diurnal cycle, another paramount shortcoming of weather
and climate models. Fig. 12 shows the considerable GCM errors for both
phase and magnitude of the precipitation diurnal cycle that − because it
arises from a well-defined and strong external forcing − would be
expected to be well-modeled. A number of current theories for the cloud
and rainfall diurnal cycle explicitly involve upper tropospheric
processes (e.g., Tian et al. *JGR*, 2004; 2005). CAMEO's high-frequency
observations will provide sorely needed data for improving GCM
performance in this area.

An especially important area of uncertainty is northern high-latitude
climate change. Evidence from limited observations and aggregate results
of GCM simulations indicates that anthropogenic climate changes will be
largest and most readily-observed at high northern latitudes (e.g.,
Hartmann et al., *Proc. NAS*, 2000). This inference, however, must be
considered with caution as the predictions are based on GCMs that
exhibit considerable differences/errors in their representation of
northern high-latitude climate. There are difficulties in simulating the
observed high latitude surface warming (Moritz et al., *Science*, 2002),
regional water recycling, dehydration processes, snow/precipitation,
snow-albedo feedback (Walsh et al., *J. Climate*, 2002), and principal
modes of circulation (e.g., Shindell et al., *Nature*, 1999; Moritz et
al., *Science*, 2002). Reconciling these differences and addressing
model shortcomings require observations with improved spatial and
temporal resolution for processes influencing high-latitude water and
energy cycles. Previous satellite observations of clouds have been
notoriously poor over high latitudes, especially during winter (Wyser
and Jones, *JGR*, in press, 2005), primarily due to reliance on visible
and infrared wavelengths and nadir-viewing geometry. The SMLS vertical,
horizontal and temporal sampling − and its ability to sound deep into
the atmosphere at these latitudes because of the dry air − gives new
information on high-latitude processes needed for model improvements.

SMLS capability for gravity wave observations is greatly improved over
that of previous MLS instruments (e.g., Wu and Zhang, *JGR*, 2004). Its
resolution of large-amplitude fast-propagating gravity waves, for
example, will help improve parameterizations of these waves − needed to
accurately model atmospheric circulation and thermal structure.

![](media/image39.png){width="2.083464566929134in"
height="0.7047244094488189in"}![](media/image39.png){width="2.0846456692913384in"
height="0.7118110236220473in"}**Add something on 'chemical weather'**

## 2.5 Earth Science Applications and Societal Needs {#earth-science-applications-and-societal-needs .unnumbered}

### 2.5.1 Transition of research to operations  {#transition-of-research-to-operations .unnumbered}

**To be added**

### 2.5.2 Support of policy decisions for well-being of life and environmental sustainability {#support-of-policy-decisions-for-well-being-of-life-and-environmental-sustainability .unnumbered}

**To be added**

### 2.5.3 Information to decrease society's vulnerability to envionmental variability {#information-to-decrease-societys-vulnerability-to-envionmental-variability .unnumbered}

**To be added**

# 3. Instruments

## 3.1 Tropospheric Pollution Imager (TROPI) {#tropospheric-pollution-imager-tropi .unnumbered}

Following material excerpted from original CAMEO document, and needs to
be updated/extended.

TROPI development, using two-dimensional detectors based on the OMI
design, started 1.5 years ago in the Netherlands. It also uses other
developments from both OMI and SCIAMACHY. TROPI measures from 300 nm (or
270 nm, currently under investigation) to 800 nm in the
ultraviolet/visible, and in a narrow range around 2.3 µm in the
short-wavelength infrared. The UV/Vis portion measures O~3~, NO~2~,
CH~2~O, SO~2~, BrO and H~2~O; aerosol optical thickness with
identification of selected aerosol types; cloud fraction and thickness;
and surface UV-B flux. The SWIR portion measures CO and CH~4~. The
overall instrument requirements are set to quantify surface emissions of
NO~2~, CO, CH~4~, SO~2~, VOCs (through the CH~2~O proxy discussed
earlier), and aerosol properties.

Two-dimensional detector arrays are used, with one axis of the array
giving spectral information and the other giving cross-track spatial
information. The UV/Vis swath width is 4700 km, and the SWIR swath width
is 2000 km; the design gives 20×20 km spatial resolution from the CAMEO
orbit. The power consumption is 300 W, mass is 250 kg, and data rate is
5 Mb/s. TROPI can be ready for launch in 2011.

## 3.2 Atmospheric Remote-sensing and Imaging Spectrometer (ARIES) {#atmospheric-remote-sensing-and-imaging-spectrometer-aries .unnumbered}

Following ARIES material is from ARIES_May_06.doc file from Tom Pagano
24 May 06, with minor formatting changes to section headings. More
editing to be done later to make consistent with rest of CAMEO document.

### 3.2.1 ARIES Observational Variables {#aries-observational-variables .unnumbered}

The Advanced Remote-sensing Imaging Emission Spectrometer (ARIES) is an
infrared spectrometer designed to measure atmospheric geophysical
parameters important to current Earth science investigations. ARIES
builds upon the observations currently being made by the Atmospheric
Infrared Sounder (AIRS) instrument, but with greatly enhanced spatial
resolution. The AIRS footprint is 13.5 km, while ARIES is designed to be
1km.

This enhancement in spatial resolution brings the global observational
capability demonstrated on AIRS to the regional scale. It also enhances
the accuracy of observations hampered by scene inhomogeneity such as
water vapor.

ARIES planned products and corresponding AIRS products are shown in
Table 1. All AIRS products listed are currently being produced in the
AIRS Version 5 Production System. Additional products such as N~2~O and
HNO~3~ are under development

The value in ARIES for CAMEO is in that it provides an accurate
temperature and water vapor profiles in addition to atmospheric
composition products to give a complete picture of the atmosphere in the
vertical column where ARIES is sensitive; mostly the mid-troposphere.
This ARIES capability complements the other measurements on CAMEO and
enhances overall retrieval accuracy when used in combination with these
instruments.

### 3.2.2 ARIES Product Accuracies {#aries-product-accuracies .unnumbered}

The design of ARIES is based on the experience gained with AIRS and TES.
We show here the results of validation of the AIRS products with the
assumption that the ARIES will preserve or enhance the AIRS retrieval
capability while offering the enhanced spatial resolution. We believe
the accuracy of the retrievals will only improve with the higher spatial
resolution of ARIES. We do not discuss the calibrated radiances, or
"Level 1" products, but must acknowledge that the stability and to some
extent, the accuracy of all products derived from AIRS are based on the
stability and accuracy of the radiances \[1\].

Temperature and Water Vapor Profiles

Fundamental to retrieval of any trace gases using infrared spectroscopy
is accurate knowledge of the temperature and water vapor in the
atmosphere. The AIRS provides the most accurate temperature and water
vapor profiles of any space instrument flown to date. Figure 1 shows a
comparison with AIRS temperature profiles with over 10^5^ radiosondes
collected over the period of Sep. 2002 -- Dec. 2004 \[2\]. Figure 1a
shows the RMS differences of a 1km layer mean temperature profiles for
clear (red), cloud cleared oceans (blue) and land (green). The RMS
differences are largest near the surface. Figure 1b shows the RMS
percent difference of a 2 km layer integrated precipitable water vapor
profiles. Considering the RMS uncertainty of the radiosondes ranges from
7% near the surface to almost 20% at 300 mb, we estimate the AIRS
retrievals and radiosondes agree to approximately 15%. Retrievals over
land are slightly degraded in version 4 and polar regions have not yet
been validated. The accuracies of these products form the basis for the
successful retrieval of CO and CO~2~ discussed below.

Atmospheric Composition

The AIRS instrument has demonstrated the ability to retrieve CO~2~, CO,
CH~4~, O~3~, and SO~2~ in the presence of clouds, daily, on a global
scale. To date, CO~2~, CO, and O~3~ have been validated. Version 5 to be
released later this year will also include CH~4~, SO~2~ and aerosol
products; validation of these products will occur in late 2006. What is
certain from the early results from AIRS is that infrared spectroscopy
is a viable approach for retrieval of atmospheric composition products,
particularly in the mid troposphere where the weighting functions of
these gases is most sensitive. Figure 2 shows global maps of CO and
CO~2~ from AIRS.![](media/image41.jpeg){width="3.109722222222222in"
height="2.064583333333333in"}![](media/image42.wmf){width="3.1145833333333335in"
height="2.053472222222222in"}![](media/image43.png){width="2.359722222222222in"
height="2.2368055555555557in"}![](media/image44.png){width="2.3444444444444446in"
height="2.2444444444444445in"}

Carbon Monoxide (CO)

Tropospheric CO abundances are retrieved from the 4.67 μm region of AIRS
spectra as one of the last steps of the AIRS team algorithm.
Optimization and validation of AIRS CO retrievals are in progress
utilizing airborne in situ profiles from NOAA CMDL and other sources as
ground truth. Comparisons with five CMDL profiles acquired during AIRS
first month of operation (September 2002) indicate agreement to
approximately 16% between 400 and 600 mb with AIRS systematically high
(See Figure 2) \[3\]. This accuracy is expected to improve in version 5
which will also include the vertical distribution functions and improved
error estimates. To date, AIRS CO maps are proving extremely useful in
the study of horizontal vertical transport.\
![](media/image45.wmf){width="2.376388888888889in" height="1.78125in"}

Carbon Dioxide (CO2)![](media/image46.wmf){width="2.1493055555555554in"
height="1.8597222222222223in"}

The most important trace gas retrieved by AIRS for the study of
anthropogenic effects on climate is carbon dioxide. AIRS CO~2~
retrievals use an analytical method for the determination of carbon
dioxide and other minor gases in the troposphere from AIRS spectra
\[4\]. The method is based on a general property of the total
differential that enables retrieval of CO~2~. The method was applied to
derive the mixing ratio of carbon dioxide and compared the AIRS results
to the aircraft flask measurements of carbon dioxide. Results show
excellent agreement to ±1.20 ppmv.

Ozone (O3)

AIRS total ozone measurements are retrieved simultaneously with
temperature and water vapor products as part of the standard retrieval.
As AIRS uses emitted infrared rather than reflected UV radiation, AIRS
can retrieve ozone amounts in darkness. Version 4 total ozone
comparisons with TOMS show, on average, agreement between AIRS and Level
3 TOMS within 5% between 50°S and 50°N, although with higher differences
in some regions, particularly desert and polar regions. Flights by
Gettelman et. al \[5\] indicate that "AIRS data tracks well the vertical
structure and variability of the aircraft ozone, with the right gradient
and dynamic range, but with a 20--30% positive bias". It is believed
that the bias in ozone is related to a temperature bias seen in Version
4 which is no longer present in Version 5. The validation of version 5
is not yet complete. Figure 4a shows the good vertical structure of the
AIRS Ozone (Laura Pan, NCAR), and Figure 4b shows the correlation with
the aircraft
comparisons.![](media/image47.wmf){width="2.7694444444444444in"
height="2.032638888888889in"}![](media/image48.png){width="3.0104166666666665in"
height="2.1729166666666666in"}

### 3.2.3 ARIES Instrument Requirements {#aries-instrument-requirements .unnumbered}

As stated in our assumption in section 2 above, the first requirement of
ARIES is that it preserve the capability demonstrated in AIRS to
retrieve the atmospheric geophysical parameters identified in Table 1.
To do this, we have selected spectral ranges, resolution and sensitivity
requirements given in Table 2. These requirements were derived by
examining the absorption lines of the individual constituents for
strength and non-interference with water vapor and other constituents.

### 3.2.4 ARIES Instrument Concept![](media/image49.wmf){width="3.3916666666666666in" height="1.8402777777777777in"} {#aries-instrument-concept .unnumbered}

The ARIES instrument concept is an infrared imaging spectrometer
covering the spectral range of 3.7 to 15.6 μm and is shown in Figure 5.
It has 4408 spectral channels, a horizontal spatial resolution of 1 km,
and scans ±50° for a full swath of 4702 km from the MEO orbit of 1500
km. The instrument collects all data in from all spectral channels at
1km all the time. An on-board data formatter and aggregator downloads
channel sets at three types as indicated in Table 3

Early estimates of the size is 0.5 x 0.5 x 1.0 m, mass is 100 kg and
power is 150 W. These estimates derive from design studies performed in
the 2001 SIRAS Instrument Incubator Program \[6\]. ARIES employs grating
spectrometer technoloy to achieve the spectral separation in the system.
This technology proved very effective on AIRS due to its high
reliability and high stability. The slit is 256 km and is oriented
along-track. Temperature control of the spectrometer is primariliy
responsible for the stability in AIRS and is employed here as well. At
this time we expect there to be 3 to 6 spectrometers needed to cover the
entire spectral range, depending on the use of higher orders in a single
spectrometer. The ARIES uses 256 (track) x 1024 (spectral) element focal
planes operating at 60K. The remainder of the system includes the latest
components including scanning, passive radiating for the optical bench
at 160K, active cryocoolers, control systems and on-board signal
processing electronics for data formatting and selection. The overall
data rate for ARIES is 53 Mbps without overhead and without data
compressin. This assumes that 100% of the time we download global mode
data, where only 512 preselected spectral channels of the 4408 and only
9 spatial samples in every 5x5 km grid are sent to the ground. 1% of the
time we download all channels and footprints for diagnostic purposes or
special events. Regional coverage occurs 5% of the time and in this
product we get full spatial resolution but only 512 channels.

![](media/image50.wmf){width="6.04375in" height="2.8958333333333335in"}

## 3.3 Scanning Microwave Limb Sounder (SMLS)  {#scanning-microwave-limb-sounder-smls .unnumbered}

The SMLS concept has been under development at JPL for several years. It
combines (a) ultra-sensitive SIS
(superconductor-insulator-superconductor) radiometers, versions of which
have been used for atmospheric measurements for 20 years, and are now in
the Japanese SMILES stratospheric instrument planned for the Space
Station and (with JPL SIS devices) in the HIFI instrument for the
European Herschel astrophysics mission, and (b) a new antenna whose
principle has been demonstrated by functional models, with geometric and
physical optics designs performed for SMLS. Flight-qualified coolers,
required for the SIS devices, are in the SMILES instrument and the
European Planck astrophysics mission. U.S. industrial sources exist for
the SMLS cooler, similar to those being developed for the James Webb
Space Telescope. The SMLS design requires \<180 W, including all
inefficiencies, for the cooler drive power.

SMLS uses advanced SIS radiometers that cover \>100 GHz bandwidth,
recently demonstrated by Caltech for radio astronomy. These give useful
atmospheric measurements with only milliseconds of measurement time (see
Fig. 7). SMLS has radiometers covering two broad bands: 180-280 GHz
(both polarizations) mainly for the troposphere, and 580-680 GHz mainly
for the stratosphere. (SMLS has 3 radiometers, compared to 7 for MLS on
Aura.) The National Radio Astronomy Observatory is implementing an array
of 200 SIS sideband-separating radiometers, as used by SMLS, around 230
GHz. The sensitivity of the SMLS radiometers is \~30× better than Aura
MLS \[Waters et al., 2006\], meaning that \~1000× less measurement time
is required by SMLS, as compared to MLS, when precision is limited by
measurement noise.

Figure **??** shows a drawing of SMLS and its signal flow block diagram.
Limb radiation is collected by a 4m × 2m primary reflector. The antenna
is scanned in the vertical, as on UARS and Aura MLS, by \~1^o^ rotation.
For SMLS a vertical scan is performed every 10 s to give along-track
sampling of 50 km, the orbital movement of the measurement track in 10
s. The conical azimuth limb scan is repeated every 0.5 s during the
vertical scan by rotating back and forth a 10-cm mirror. The ±65^o^
azimuth scan range enables a 7700 km cross-track swath from the 1500-km
CAMEO orbit. A measurement is made every 3 ms to give 50 km cross-track
sampling that matches the along-track sampling. 'Overscan' in the
vertical accounts for Earth's oblateness and changes in vertical scan
range with azimuth. A multipoint calibration is performed between each
azimuth scan. All mechanisms have 5-year (or longer) operational
lifetime.

![](media/image51.png){width="3.0645669291338584in"
height="2.2271653543307086in"}

![](media/image52.png){width="4.284722222222222in"
height="3.238888888888889in"}

Both the SMLS azimuth and vertical scans are programmable -- as is the
measurement suite, which is selected by tuning local oscillators. One
set of measurements is made continuously (e.g., H~2~O, cloud ice,
temperature, O~3~, CO); other sets of related measurements are
time-shared to reduce the required number of spectrometers. Time-sharing
modes can be changed as often as each vertical scan. The programmability
and spectral coverage allow measurements of new species: in principle,
nearly any species with a dipole moment. Spectral surveys can be
performed to test, within the limits of the SMLS sensitivity and
spectral ranges, the completeness of our knowledge of atmospheric
composition.

Figure **??** shows the measurement time needed to obtain a spectral
line radiance signal-to-noise of 10 for producing useful the upper
tropospheric measurements. The available measurement time depends upon
the mode of the SMLS scan, which is programmable in both horizontal and
vertical. A 'maximum global mode' with measurements at 20 points in the
vertical and every 50×50 km in the horizontal over a 7700 km cross-track
width allows 0.003 s for each individual measurement; a 'regional study
mode' with, for example, measurements at 5 points in the vertical and
every 50×50 km in the horizontal over a cross-track width of 2000 km
allows 0.05 s for each measurement; a 'local study mode' with, for
example, measurements at 3 points in the vertical and every 50×50 km in
the horizontal over a 200 km cross-track width allows 1 s for each
measurement. There is a 'continuum' of modes, easily implemented simply
by programming the scan ranges. The available measurement time can be
increased by degrading the spatial and/or temporal resolution: a factor
of 4 increase, for example, is gained by changing from 50×50 km to
100×100 km horizontal resolution, which can be done in ground data
processing. The SMLS individual integration time is the same for all
scan modes, giving a data that is constant and does not depend upon scan
mode.

All SMLS stratospheric measurements will be produced with useful
resolution at a precision of a few percent. The vertical resolution will
vary between 1 and 3 km, and horizontal between 50 and 500 km, depending
upon the specific measurment.

All the SMLS technologies have been flight-qualified. Development of key
SMLS components is ongoing through internal JPL funding. Major needs for
developing the satellite instrument are (a) studies to get better
estimates of mass, power, the configuration envelope, number and type of
spectrometers, etc., and (b) development of an instrument that could be
used from mountaintop to determine practical limitations for the new
tropospheric measurements.

SMLS power consumption is 400 W (150 W less than Aura MLS), its mass is
450 kg (same as Aura MLS), and its data rate is 5 Mb/s. It can be ready
for launch in 2011.

![](media/image53.wmf){width="7.099212598425197in"
height="2.925196850393701in"}

**Fig. ??**. SMLS measurement time needed for an upper tropospheric
spectral line radiance signal-to-noise of 10 for various species. .
Because of the large dynamic range in many species abundances, useful
measurements can be obtained with a signal-to-noise of 3, which reduces
the required measurement time 9x from that shown here. Colors of the
bars give representative abundances for different situations. Blue is
for typical or minimum abundances; pink for enhanced abundances that
have been observed or inferred; brown for enhanced boundary layer
abundances that can be convectively transported to the upper
troposphere; grey for soluble species that may reach the upper
troposphere less easily. This plot is for a tropical 'background'
atmosphere and 9 km height; it includes 2-3x attenuation of the target
molecule signals by water vapor continuum, and spectral line wings of
'interfering' gases. For the tropical troposphere above 12 km, a region
of considerable current interest, SMLS signals are typically 2-3x
stronger than indicated here. All these measurements are made in the
180-280 GHz region, from spectral lines selected by considerations of
(a) line strength, (b) freedom from interference, and (c) instrument
simplification. Cloud ice measurements from 'continuum' emission, and
temperature from O^18^O, are obtained with good signal-to-noise in
milliseconds.

# 4. Launch vehicle and satellite bus 

Following material excerpted from original CAMEO document, and needs to
be extended.

CAMEO can be inserted directly into the desired mid-Earth orbit by a
two-stage Delta-II rocket. Add appropriate statement on satellite bus.
Fig. 15 shows CAMEO (1) stowed for launch and (2) deployed in orbit.
CAMEO can also be implemented with the two instruments on separate
satellites flying in formation.

![](media/image54.png){width="2.9200787401574804in"
height="2.030708661417323in"}![](media/image55.png){width="1.9661417322834647in"
height="1.9708661417322835in"}

Add paragraph (or subsection) on orbit environment, addressing MEO
radiation issue.

# 5. Operations 

CAMEO operations can be similar to those of Aura, with central mission
operations and remote science teams doing instrument operations. CAMEO
does a yaw maneuver 8 times per year to keep its 'cold side' (containing
radiators) away from direct sunlight. The yaw maneuver is
straightforward to implement, and does [not]{.underline} degrade
measurement coverage because the instruments have symmetric measurement
swaths on both sides of the orbit track.

Add paragraph on data transmission to ground.

A 5-year design lifetime (for measurement of interannual variability)
and a launch date of 2011 (in anticipation of some overlap with Aura)
are proposed. Do we want to keep to this date given in original CAMEO
doc?

# 6. Data processing 

Following taken from 16 May 2005 CAMEO document -- which needs to be
extended.

Data processing and validation are expected to be the responsibility of
the instrument science teams, as done successfully for Aura's MLS and
OMI by the teams proposing the CAMEO mission concept.

A two-tier processing scheme is envisaged for SMLS.  The first is
routine continuous production of a 'spatial low-resolution' dataset
(maybe 500×500 km horizontal as was planned for HIRDLS on Aura) with
full temporal resolution. This contains geophysical parameters that are
produced using a combination of optimal estimation and, for some
products, more approximate but faster methods such as neural-networks. 
It will be made publicly available either through a central facility or
through an extension of the Science Investigator-led data Processing
System (SIPS) arrangement now used for Aura. The second tier is
production of high-resolution 'regional' datasets generated with full
optimal estimation algorithms as used for MLS on Aura. A concept will be
explored whereby portable 'regional' software is made available for data
processing by 'regional' users; this can reduce computational
requirements on a central facility. An SMLS near real time capability
for operational applications will be implemented. We anticipate the U.K.
University of Edinburgh contributing to the SMLS data processing
algorithms and validation, as done for previous MLS experiments.

The TROPI algorithms will be based on algorithms used for previous
instruments such as OMI. OMI data sets are produced by the SIPS at NASA
GSFC and the fully SIPS-compliant facility at KNMI in the Netherlands.
An OMI near real time facility is under development to provide data for
weather forecasts, smog forecasts, UV-B forecasts and volcanic plume
data for aviation control. Similar products are envisaged for TROPI on
CAMEO.

# Appendices 

# 

## A1. Comparing coverage for CAMEO and TRAQ orbits, and with two satellites  {#a1.-comparing-coverage-for-cameo-and-traq-orbits-and-with-two-satellites .unnumbered}

Nominal CAMEO orbit: 1500 km altitude, 52^o^ inclination.

Nominal TRAQ orbit: 720 km altitude, 57^o^ inclination.

![](media/image56.png){width="6.863194444444445in"
height="2.6638888888888888in"}

![](media/image57.png){width="6.863194444444445in"
height="2.6638888888888888in"}

![](media/image58.png){width="6.863194444444445in"
height="2.6638888888888888in"}

![](media/image59.png){width="6.863194444444445in"
height="2.6638888888888888in"}

![](media/image60.png){width="6.863194444444445in"
height="2.6638888888888888in"}

## A2. CAMEO 'measurement traceability' {#a2.-cameo-measurement-traceability .unnumbered}

## A3. Currently-planned future satellite instruments {#a3.-currently-planned-future-satellite-instruments .unnumbered}

## A4. ARIES instrument details {#a4.-aries-instrument-details .unnumbered}

## A5. TROPI instrument details {#a5.-tropi-instrument-details .unnumbered}

## A6. SMLS instrument details {#a6.-smls-instrument-details .unnumbered}

## A7: Orbital Environment  {#a7-orbital-environment .unnumbered}

## A8. Simulation results (e.g., SMLS upper trop retrieval simulations) {#a8.-simulation-results-e.g.-smls-upper-trop-retrieval-simulations .unnumbered}

## A9. Risk Mitigation (Do we want this? It was asked for by NRC RFI) {#a9.-risk-mitigation-do-we-want-this-it-was-asked-for-by-nrc-rfi .unnumbered}

Following is from 16 May 2005 CAMEO document -- which needs to be
extended if we include such a section.

SMLS risk can be mitigated by developing a demonstration instrument for
mountaintop measurements. (Demonstration of useful mountaintop
measurements could allow considerations for deployment of instruments on
skyscrapers, as an adjunct to the satellite measurements, for detailed
observations over urban areas. An aircraft instrument would be a
valuable research and validation tool.) SMLS has identical 180-280 GHz
radiometers at orthogonal polarizations, which provide redundancy for
upper tropospheric measurements. There is redundancy in some
stratospheric measurements, including re-programming some to the 180-280
GHz radiometers (but with reduced measurement quality). The scan and
cooler electronics have redundancy.

## A?: Others?  {#a-others .unnumbered}

# References 

1.  Aumann, H. H. , D. Gregorich, S. Gaiser and M.T. Chahine,
    \"Application of Atmospheric Infrared Sounder (AIRS) Data to Climate
    Research\", Proc. SPIE 5570 Maspalomas, Spain, September 2004.

2.  Divakarla, M., C. Barnet, M. D. Goldberg, L. McMillin, E. S.
    Maddy, W. W. Wolf, L. Zhou, and X. Liu (2006), Validation of
    Atmospheric Infrared Sounder temperature and water vapor retrievals
    with matched radiosonde measurements and forecasts, *J. Geophys.
    Res.*, *111*, doi:10.1029/2005JD006116

3.  W. McMillan et al., "Daily Global Maps of Carbon Monoxide: First
    Views from NASA's Atmospheric Infrared Sounder (AIRS)", Geophys,Res.
    Lett, Vol. 32, L11801, doi:10.1029/2004GL021821, 2005

4.  Chahine, M.; Barnet, C.; Olsen, E. T.; Chen, L.; Maddy, E "On the
    determination of atmospheric minor gases by the method of vanishing
    partial derivatives with application to CO2". Geophys. Res. Lett.,
    Vol. 32, No. 22, L22803 10.1029/2005GL024165.

5.  Gettelman A ,et. al. "Validation of Aqua satellite data in the upper
    troposphere and lower stratosphere with in situ aircraft
    instruments", Geophysical Research Letters 31 (22): Art. No. L22107
    NOV 24 2004

6.  T. Kampe, H. Chase, D. Michaels, "SIRAS-G the Spaceborne Infrared
    Atmospheric Sounder: applications in Earth science", [Proc. SPIE
    Vol.
    5865](http://bookstore.spie.org/index.cfm?fuseaction=detailvolume&productid=605341&coden=PSISDG), p.
    98-107

7.  S. A. Carn, L. L. Strow, S. de Souza-Machado, Y. Edmonds, and S.
    Hannon, "Quantifying tropospheric volcanic emissions with AIRS: The
    2002 eruption of Mt. Etna (Italy)" Geophysical Research Letters,
    Vol. 32, L02301, doi:10.1029/2004GL021034, 2005

8.  S. G. DeSouza-Machado, L. L. Strow, S. E. Hannon, and H. E.
    Motteler, "Infrared dust spectral signatures from AIRS", Geophys.
    Res. Lett, Vol.. 33, L03801, 10.1029/2005GL024364, 2006

9.  Susskind, J., C. Barnet, J. Blaisdell, L. Iredell, F. Keita, L.
    Kouvaris, G. Molnar, and M. Chahine (2006), Accuracy of geophysical
    parameters derived from Atmospheric Infrared Sounder/Advanced
    Microwave Sounding Unit as a function of fractional cloud cover, *J.
    Geophys. Res.*, *111*, D09S17, doi:10.1029/2005JD006272

Froidevaux, L. N.J. Livesey, W.G. Read, R.J. Salawitch, J.W. Waters,
B.J. Drouin, I.A. MacKenzie, H.C. Pumphrey, P. Bernath, C. Boone, R.
Nassar, S. Montzka, J. Elkins, D. Cunnold, D. Waugh, \"Decreases in
upper atmospheric chlorine,\" *Geophys. Res. Lett.*, submitted.

Hunten, D.M., "Ozone", in *The Upper Atmosphere and Magnetosphere*,
pages 156-168, National Academy of Sciences, Washington, D.C., 1977.

Jacob et al., GRL, 1999

Manney, G.L., M.L. Santee, N.J. Livesey, L. Froidevaux, W.G. Read, H.C.
Pumphrey, J.W. Waters, S. Pawson, \"EOS Microwave Limb Sounder
Observations of the Antarctic Polar Vortex Breakup in 2004,\" *Geophys.
Res. Lett. 32*, L12811,doi:10.1029/2005GL022823, 28 Jun 2005.

National Research Council, "Causes and effects of stratospheric ozone
reduction: an update", 1982.

Santee, M.L, G.L. Manney, N.J. Livesey, L. Froidevaux, H.C. Pumphrey,
W.G. Read, M.J. Schwartz, J.W. Waters, \"Polar processing and
development of the 2004 Antarctic ozone hole: First results from Aura
MLS,\" *Geophys. Res. Lett. 32*, L12817, doi:1029/2005GL022582, 28 Jun
2005.

Ziemke et al., JGR, 2006

[^1]: CAMEO provides the mid-Earth orbit mission capability identified
    by the Decadal Survey Health and Human Security 'Respiratory and
    cardiovascular disease' subpanel as a priority 'bridge' linking air
    quality and other panel topics.

[^2]: CAMEO provides most, if not all, of the atmospheric information
    identified as a focus of the Decadal Survey Water Resources and
    Global Hydrological Cycle panel.

[^3]: CAMEO provides the needed 'ConTSat' (Convective transport of trace
    species, heat and momentum) mission limb scanning capability
    identified by the Decadal Survey Panel on Climate Variability and
    Change.

[^4]: CAMEO provides measurements of all the chemical species identified
    by the Decadal Survey Health and Human Security Panel as needed for
    the 'UV exposure and skin cancer' issue, except OH (for which HO~2~
    is a proxy) and IO.

[^5]: Blue font, in this version of document identifies wording that,
    especially, needs work.

[^6]: Red font, in this version of document identifies questions or
    actions needed.

[^7]: For example (1) Decadal Survey Health and Human Security
    'Respiratory and cardiovascular disease' subpanel; and (2) Community
    Workshop on Air Quality Remote Sensing from Space: Defining an
    Optimum Observing Strategy held 21-23 February 1006, National Center
    for Atmospheric Research, Boulder, Colorado, USA.