ARM TR-051

> Rotating Shadowband Spectroradiometer (RSS) Handbook
>
> May 2006
>
> P. Kiedron
>
> J. Schlemmer
>
> M. Klassen
>
> Work supported by the U.S. Department of Energy,
>
> Office of Science, Office of Biological and Environmental Research

# Contents {#contents .Heading-Front}

[1. General Overview 2](#general-overview)

[2. Contacts 3](#contacts)

[3. Deployment Locations and History
4](#deployment-locations-and-history)

[4. Near-Real-Time Data Plots 4](#near-real-time-data-plots)

[5. Data Description and Examples 4](#data-description-and-examples)

[6. Data Quality 8](#data-quality)

[7. Instrument Details 9](#instrument-details)

# Figures {#figures .Heading-Front}

[1. From right to left: RSS105, UV-RSS104 and RSS103 in May 2003
2](#__RefHeading___Toc96409054)

[2. 1-sigma photon and read noise in direct and diffuse irradiances
7](#__RefHeading___Toc96409055)

[3. RSS optics (IC-integrating cavity, S-slit, SH-shutter,
L1-collimating lens, P1, P2-prisms, L2-camera lens, CCD-charge-coupled
device) 10](#__RefHeading___Toc96409056)

[4. Mage of Hg and Cd lines recorded by the CCD
10](#__RefHeading___Toc96409057)

[5. Filter function for RSS105 and RSS103
11](#__RefHeading___Toc96409058)

[6. RSS shadowbanding geometry 12](#__RefHeading___Toc96409059)

[7. Calibration events till the end of November 2004
14](#__RefHeading___Toc96409060)

# Tables {#tables .Heading-Front}

[1. 2](#__RefHeading___Toc96412467)

[2. 4](#__RefHeading___Toc96412468)

[3. 13](#__RefHeading___Toc96412469)

# General Overview

The rotating shawdowband spectroradiometer (RSS) implements the same
automated shadowbanding technique used by the multifilter rotating
shadowband radiometer (MFRSR), and so it too provides
spectrally-resolved, direct-normal, diffuse-horizontal, and
total-horizontal irradiances, and can be calibrated in situ via Langley
regression. The irradiance spectra are measured simultaneously at all
spectral elements (pixels) in 360-nm to 1050-nm range. Figure 1 depicts
the RSS105 at the Southern Great Plains (SGP) Oklahoma site with the
UV-RSS104 and RSS102 during the Aerosol Intensive Operational Period
(IOP) in May 2003.

![](media/image1.jpeg){width="4.0in" height="3.0in"}

[]{#__RefHeading___Toc96409054 .anchor}Figure 1. From right to left:
RSS105, UV-RSS104 and RSS103 in May 2003

The currently deployed RSS105 was preceded with two prototypes, RSS103
and RSS102, which also operated at SGP in three distinct periods since
August 1997 (see Table 1). Data from the two prototypes and RSS105 till
March 30, 2006 are available at
<http://iop.archive.arm.gov/arm-iop/0special-data/asrc-rss/> in ascii
format. All RSS105 data are available from ARM Archives in netCDF
format. RSS105 data in ARM Archives are lamp calibrated irradiances. The
accuracy of irradiance produced by RSS is expected to be better than ±5%
that includes calibration and instrument stability errors. Higher
accuracy can be obtained when the responsivity is tied to the solar
extraterrestrial irradiance via Langley regression. This approach is
recommended when high precision measurements of optical depth are
required. The calibration constants from Langley regressions (so called
Vo's) are available from the IOP server
<http://iop.archive.arm.gov/arm-iop/0special-data/asrc-rss/rss105/langley/>
.

[]{#__RefHeading___Toc96412467 .anchor}Table 1.

+---------------+------------------+---------------+------------------+
| **Data        |                  |               |                  |
| A             |                  |               |                  |
| vailability** |                  |               |                  |
+---------------+------------------+---------------+------------------+
|               | RSS105           | RSS103        | RSS102           |
+---------------+------------------+---------------+------------------+
| Location      | SGP              | SGP           | SGP              |
+---------------+------------------+---------------+------------------+
| Operational   | 05/09/03 -       | 09/2          | 07               |
| epochs        | Present          | 9/01-06/27/02 | /22/99--08/04/00 |
|               |                  |               |                  |
|               |                  | 08/12         |                  |
|               |                  | /97--10/05/98 |                  |
+---------------+------------------+---------------+------------------+
| Measurement   | From sunrise to  |               |                  |
| period        | sunset           |               |                  |
+---------------+------------------+---------------+------------------+
| Measurement   | 1 shadowbanding  |               |                  |
| rate          | cycle per min    |               |                  |
+---------------+------------------+---------------+------------------+
| Number of     | From 570 spectra |               |                  |
| spectra       | in Winter to 870 |               |                  |
|               | spectra in       |               |                  |
| per day       | Summer           |               |                  |
+---------------+------------------+---------------+------------------+

Note: RSS103 was also deployed at the North Slope of Alaska (NSA) site
from 03/04/1999 till 08/16/1999. Data are available from Atmospheric
Sciences Research Center (ASRC) server only.

Irradiances from RSS's were used in research resulting in several
significant scientific contributions. Michalsky et al. (1999) determined
absorption cross-sections of O2-O2; Min et al. (1999 and 2001) developed
methods to measure cloud optical depth from oxygen A-band that lead to
cloud detection beyond microwave radar sensitivity; Kiedron et al.
(1999) utilized RSS in irradiance standards intercomparison; Mlawer et
al. (2000) used RSS direct and diffuse spectra to validate line-by-line
clear sky shortwave model; Schmid et al. (1999) used aerosol retrieved
from RSS; Harrison et al. (1999 and 2003) detected significant accuracy
issues in solar source functions below 450nm; Michalsky et al. (2001)
retrieved water vapor column; Kiedron et al. (2001 and 2003) retrieved
water vapor column in Arctic in both clear sky and overcast conditions;
most recently Gianelli et al. (2005) used RSS data to retrieve NO2
column at SGP.

# Contacts

## Mentor

Peter Kiedron (Instrument Mentor)

Atmospheric Research Center

SUNY at Albany

251 Fuller Road

Albany, NY 12203

Phone: 518-437-8737

Fax: 518-437-8711

E-mail: <kiedron@asrc.cestm.albany.edu>

Jim Schlemmer (Data Processing)

Atmospheric Research Center

SUNY at Albany

251 Fuller Road

Albany, NY 12203

Phone: 518-437-8718

Fax: 518-437-8711

E-mail: <jim@asrc.cestm.albany.edu>

Mark Klassen (Instrument Calibration)

SGP Cart Site Operations

Phone: 580-388-4053

E-mail:
[[markk@ops.sgp.arm.gov]{.underline}](mailto:Miker@ops.sgp.arm.gov)

## Instrument Developer

**RSS105**: Yankee Environmental Systems, Airport Industrial Park, 101
Industrial Blvd., Turners Falls, MA 01376 (413) 863-0200

**RSS102 & RSS103**: ASRC, SUNY at Albany, 251 Fuller Road, Albany, NY
12203 (contact: P. Kiedron at <kiedron@asrc.cestm.albany.edu> or
L. Harrison <lee@asrc.cestm.albany.edu>)

# Deployment Locations and History 

This section is not applicable to this instrument.

# Near-Real-Time Data Plots

This section is not applicable to this instrument.

# Data Description and Examples

## Data File Contents

### Primary Variables and Expected Uncertainty

The primary quantities measured by the system are:

1.  the direct normal solar spectral irradiance (W/m^2^/nm)

2.  the total horizontal solar spectral irradiance (W/m^2^/nm)

3.  the diffuse horizontal solar spectral irradiance (W/m^2^/nm).

Each of these quantities is measured in 360-nm-1050-nm range. In the
case of RSS105, 1001 pixels (adjacent spectral elements) are
simultaneously measured in this range. The resolution is
pixel-dependent. Table 2 lists Full Width at Half Maximum (FWHM) at
seven selected wavelengths, both in nm and in pixels. The exact filter
function for each pixel is provided in files available at:
<http://iop.archive.arm.gov/arm-iop/0special-data/asrc-rss/>

[]{#__RefHeading___Toc96412468 .anchor}Table 2.

  ------------------- ----------------- ------------------ -----------------
  **Spectral                                               
  Characteristics**                                        

                      RSS105            RSS103             RSS102

  Number of pixels    1024              512                1024

  Nominal Spectral    360-1050          360-1050           360-1050
  Range (NSR)\[nm\]                                        

  Number of Pixels    1001              442                988
  within NSR                                               

  Resolution (FWHM)                                        
  \[nm\]/\[pixels\]                                        

  \@400nm             0.37/1.56         1.24/2.32          0.37/1.52

  \@500nm             0.62/1.36         2.57/2.47          1.14/2.44

  \@600nm             1.05/1.40         4.84/2.81          1.77/2.32

  \@700nm             1.57/1.44         7.80/3.12          2.21/2.00

  \@800nm             2.16/1.52         11.02/3.37         2.53/1.75

  \@900nm             2.79/1.63         14.32/3.61         2.81/1.62

  \@1000nm            3.42/1.78         17.11/3.83         3.10/1.58
  ------------------- ----------------- ------------------ -----------------

Table 2. (cont'd)

+----------------+----------------+-----------------+----------------+
| **Spectral     |                |                 |                |
| Cha            |                |                 |                |
| racteristics** |                |                 |                |
+----------------+----------------+-----------------+----------------+
| Filter         |                |                 |                |
| functions      |                |                 |                |
+----------------+----------------+-----------------+----------------+
| 95% below      | Gaussian       | Gaussian        | Gaussian       |
| maximum        |                |                 |                |
+----------------+----------------+-----------------+----------------+
| Gaussian       | rss            | rs              | rrs            |
| parameter from | 105_GaussWidth | s103_GaussWidth | 102_GaussWidth |
+----------------+----------------+-----------------+----------------+
| Below 95% is   | rss            | rs              | rss            |
| defined by     | 105_ff_respEQ1 | s103_ff_respEQ1 | 102_ff_respEQ1 |
| following      |                |                 | rss102_RespQM  |
| files          | rss105_respQM  | rss103_RespQM   |                |
|                |                |                 | rss102_RespW   |
|                | rss105_RespW   | rss103_RespW    |                |
+----------------+----------------+-----------------+----------------+

Note: In RSS105 the pixel 523 (approximately at 503 nm) is dead. The
average of 522 and 524 pixels is reported instead resulting in increased
resolution at this pixel.

#### Definition of Uncertainty

**Overall Uncertainties for Primary Quantities Measured**

**Photon and Read Noise**: The read noise of the charge-coupled device
(CCD) and Poisson photon noise were characterized before deployment.
Also, data from each calibration event are analyzed to verify whether
noise parameters remain unchanged. The standard deviation of this noise
is calculated for every pixel of every scan and submitted with
calibrated data (RSS105). The relative value of this noise is larger in
absorption bands and strong Fraunhofer lines and near 360 nm and 1050
nm. See Figure 2 for typical noise values in percent of diffuse and
direct irradiances.

**Radiometric Calibration Error**: We estimate that calibration transfer
errors are less than ±2% for each individual calibration.

**Absolute Radiometric Scale Error**: The National Institute of
Standards of Technology (NIST) specifies that the individual FEL lamp's
accuracy is as large as ±4%. However, we have reasons to believe that
the methodology used to calibrate RSS yields lower errors. We base this
on results found in papers by Kiedron et al. (1999) when many
calibration standards were compared, including Licor and on RSS-derived
extraterrestrial spectrum that differs less than 4% from the accepted
standard of extraterrestrial spectrum (see Harrison et al. \[1999 and
2003\]) for wavelengths larger than 450 nm.

![](media/image2.wmf){width="5.990277777777778in"
height="2.870833333333333in"}

[]{#__RefHeading___Toc96409055 .anchor}Figure 2. 1-sigma photon and read
noise in direct and diffuse irradiances

**Nonlinearity**: The nonlinearity is detected and characterized from
calibration data and then corrected in each scan of RSS105. We estimate
that uncertainty because of this correction may result in errors of up
to ±1% in the regions of the spectra where signal is strong.

**Wavelength errors**: Because of temperature changes of the optics and
mechanical stress, there is a slight spectral shift during daily
measurement. The shifts are small (less than 0.5 pixels). Nevertheless,
they are detected in each scan and applied to responsivity. A special
correlation technique with Fraunhofer spectrum is used to detect these
wavelengths shifts.

**Stability**: During the first several months of operation, RSS105
exhibited strong responsivity drift. The rate of drift showed a steady
decline. As of November 2004 the drift appears to be less than 1% per
month. Bimonthly calibrations and use of interpolated responsivity
assures that the drift has no impact on the final data quality.

**Stray Light**: When comparing RSS with modeled irradiance, one has to
keep in mind that the modeled irradiance must be calculated with the
exact RSS filter functions (See Figure 5). If truncated versions of
these functions are used, then some discrepancies appear in absorption
bands in the form of a residual stray light. On the other hand, it is
possible to remove the stray light from RSS spectra by the method of
deconvolution (see Kiedron et al. \[2002\]); however, it is simpler to
calculate the modeled spectra using exact RSS filter functions.

### Secondary/Underlying Variables

This section is not applicable to this instrument.

### Diagnostic Variables

This section is not applicable to this instrument.

### Data Quality Flags

This section is not applicable to this instrument.

### Dimension Variables

This section is not applicable to this instrument.

## Annotated Examples

This section is not applicable to this instrument.

## User Notes and Known Problems

Automated Quality Control/flagging contained within netCDF files.

While netCDF files of processed and calibrated RSS data are not produced
at this point, we denote missing data as -999.

## Frequently Asked Questions

This information is currently unavailable.

# Data Quality

## Data Quality Health and Status

No routine implementation.

## Data Reviews by Instrument Mentor

**Instrument Mentor Quality Control Checks**

-   **QC frequency**: Daily

-   **QC delay**: Day+2

-   **QC type**: Graphical plots

-   **Inputs**: Raw data

-   **Outputs**: Summary reports

-   **Reference**:

**Site Scientist/Data Quality Office Quality Control Checks**

Not implemented yet.

**Value-Added Procedures and Quality Measurement Experiments**

No value added products have been implemented yet.

**Examples of Data**

See data files at
<http://iop.archive.arm.gov/arm-iop/0special-data/asrc-rss/> .

**Data Quick Looks/Near Realtime**

Not available yet.

## Data Assessments by Site Scientist/Data Quality (DQ) Office

This section is not applicable to this instrument.

## Value-Added Procedures and Quality Measurement Experiments

This section is not applicable to this instrument.

# Instrument Details

## Detailed Description

### List of Components

Not available yet.

### System Configuration and Measurement Methods

**Spectrograph and CCD**

The optics of RSS is depicted in Figure 3 with the actual ray-trace. All
lenses are plano-convex singlets; achromatization was not attempted to
keep the number of surfaces to a minimum. Because of the chromatic
aberrations, the image plane is oblique to the optical axis. For this
reason the CCD reflects some of impinging light away from the optical
system into the dark cavity. The CCD has no window to avoid reflections
between the window and the surface of the CCD.

![](media/image3.wmf){width="4.326388888888889in"
height="3.229861111111111in"}

[]{#__RefHeading___Toc96409056 .anchor}Figure 3. RSS optics
(IC-integrating cavity, S-slit, SH-shutter, L1-collimating lens, P1,
P2-prisms, L2-camera lens, CCD-charge-coupled device)

Not shown in Figure 3 is the sandwich of two color glass filters. In
RSS105 they are located between slit and collimating lens. They reduce
dynamic range and increase the out-of-band rejection in UV and near
infrared (NIR) regions in particular. However, we have not yet confirmed
our hypothesis that they contribute to instrument radiometric
instability.

The slit image is formed on the two-dimensional CCD (Figure 4), but
during the operation all rows within the image are binned during a
single readout. The exposure is selected before the shadowbanding to
maximize the dynamic range of the CCD. Exposures can vary between 0.2-5
seconds, which in combination with the 16-bit readout row capacity,
results in 20+ bits combined dynamic range. The CCD is electronically
shuttered, which means that the shutter is open when image rows are
binned into the readout row.

![](media/image4.wmf){width="4.586111111111111in"
height="1.4736111111111112in"}

[]{#__RefHeading___Toc96409057 .anchor}Figure 4. Mage of Hg and Cd lines
recorded by the CCD

At the end of each shadowbanding cycle the mechanical shutter is closed
to acquire the dark signal at the same exposure time that was used to
measure signals in four positions of the shadowband. To keep low dark
counts and constant quantum efficiency, the CCD is cooled with a
PID-controlled thermoelectric cooler.

![](media/image5.wmf){width="5.990277777777778in"
height="2.4631944444444445in"}

[]{#__RefHeading___Toc96409058 .anchor}Figure 5. Filter function for
RSS105 and RSS103

The optical design results in exceptionally high out-of-band rejection,
which is illustrated in Figure 5, wherein filter functions that were
derived from laser and spectral lamps measurements for RSS105 and the
lower-resolution RSS103 are depicted.

**Shadowbanding method**

The diffuser is shaded at periodic intervals by a rotating shadowband.
During these intervals, the total horizontal diffuse radiation is
measured for each pixel simultaneously. The shadowband is moved so the
diffuser is fully exposed to the sky. The total horizontal downward
radiation is then measured. The difference between the total horizontal
and diffuse radiation gives the downward component of the direct beam
solar irradiance; from this quantity, the direct beam solar irradiance
is easily calculated.

The measurements are corrected for the cosine response of the
diffuser/sensor assembly as well as the "excess sky" obscured by the
shadowband during the diffuse radiation measurement.

In one RSS shadowbanding cycle, five measurements (including dark
signal) are performed. In Figure 6, three shadowband positions (two
corrections \[CorrMinus and CorrPlus\] and blocked \[Blocked\] with
respect to the diffuser) are presented. The counts of direct and diffuse
horizontal irradiances are obtained with the following equations:

DiffHor=\[Unblocked-(CorrMinus+CorrPlus)/2+Blocked-Dark\]/CosDiffCor

DirHor= \[(CorrMinus+CorrPlus)/2-Blocked\]/CosDirCor

TotHor= DiffHor+ DirHor

DirNorm=DirHor/cos(SZA)

Where CosDiffCor and CosDirCor are cosine corrections for diffuse and
direct components, respectively. CosDiffCor is calculated for Rayleigh
sky at SZA=45° case.

![](media/image6.jpeg){width="4.303472222222222in" height="3.21875in"}

[]{#__RefHeading___Toc96409059 .anchor}Figure 6. RSS shadowbanding
geometry

The equations overestimate direct and underestimate diffuse because the
correction (CorrMinus+CorrPlus)/2 does not eliminate all errors
resulting from the 8.1° field of view (FOV) angle. The estimates will
have larger bias for aerosol size distribution n(r)=Ar\^-k when k is
small. The estimation of these errors for geometry of the RSS has not
been completed. However, a circular aperture of 8° in blocked--unblocked
scheme (no corrections) underestimates optical depth by 2%-5% for
typical k=4.2-4.4. Thus one may expect that the correction scheme used
in RSS results in significantly smaller errors.

The shadowbanding geometry is well defined by the band's dimensions and
its position with respect to the diffuser (see Table 3). Therefore, one
can calculate RSS irradiances using any sky radiance model. This is a
recommended usage of RSS data for high-quality model-measurement
comparisons.

[]{#__RefHeading___Toc96412469 .anchor}Table 3.

  ------------------------------------------------------------------------
  **Shadowbanding                                     
  Geometry**                                          
  ---------------------- ----------- ---------------- --------------------
                         RSS105      RSS103           RSS102

  Diffuser aperture      0.25"                        

  Shadowband width       8.1°                         

  Shadowband radius      3.50"                        

  Shadowband length      135°                         

  Shadowband position at ±9°                          
  corrections                                         

  Shadowband axis angle  45°         Parallel with    Parallel with Earth
                                     Earth axis       axis

  Shadowband center on   yes                          
  diffuser                                            
  ------------------------------------------------------------------------

A detailed discussion of the instrument\'s measurement methods is found
in Harrison and Michalsky (1994) and in Kiedron et al. (2002).

**Description of Observational Specifications**

As mentioned above, the spectral irradiances (direct, diffuse, and
total) are measured at 1001 adjacent wavelengths between 360 nm and
1050 nm. These measurements are made over passbands (fwhm) varying from
0.37 nm to 3.45 nm (RSS105).

### Specifications

This section is not applicable to this instrument.

## Theory of Operation

This information is currently unavailable.

## Calibration

For calibration information, see **7.4.4 Additional Documentation**

### Theory

RSS105 is calibrated radiometrically with a Licor calibrator (once a
month) and a Portable Calibrator (twice a month). The wavelength
calibration with HgCd Oriel Calibrator was found to be unnecessary and
was discontinued in March 2004. The Licor irradiance is traceable to
NIST irradiance standards. Our experience indicates excellent stability
and accuracy of this source (Kiedron et al. 1999). The Portable
Calibrators were developed for UV spectroradiometers at ASRC. We
transfer red their irradiance calibration via RSS and Licor. The current
experience with them indicates excellent stability (better than ±2%)
with respect to Licor in 350-1050 nm range.

The shadowbanding method of measurement permits radiometric
self-calibration of relatively stable instruments via Langley
regression. For example, ±5% semiannual drift of RSS102 was corrected
with Vo's trends from Langley regression. Details on Langley regression
and the algorithm used can be found in Harrison and Michalsky (1994).

### Procedures

For further information and details, see **7.4.4 Additional
Documentation**

### History

Because of weather conditions and other unforeseen circumstances,
calibration schedule has to be flexible. At best, we expect two
calibrations per month with Portable Calibrator and one calibration per
month with Licor. On special occasions, we may have more than two
calibrations during one day. Figure 7 depicts calibration event
frequency till the end of November 2004. Since November 2005 calibration
are performed once every two weeks.

![](media/image7.wmf){width="5.992361111111111in"
height="2.3041666666666667in"}

[]{#__RefHeading___Toc96409060 .anchor}Figure 7. Calibration events till
the end of November 2004

See **7.4.4 Additional Documentation**

## Operation and Maintenance

**Maintenance Procedures**

RSS band movement and shading when direct sun is available is checked
daily. Then the diffuser is wiped with distilled water. Any malfunctions
are reported to the mentor, and the mentor then initiates corrective
actions (except for power recycling).

**Supplemental Assessment of Instrument Calibration and Maintenance
Procedures**

**May 2003**: RSS105 is deployed and a very rigorous calibration
scheduled is instituted (calibration with Licor once a month,
calibration with Portable Calibrator twice a month and spectral
calibration with Oriel HgCd lamp once a month)

**July 2003**: Significant drift in responsivity is detected. We decide
to maintain the initial calibration schedule.

**February 2004**: Baseline change request (BCR) 00776 (Remove the
embedded Linux computer at RSS105) is implemented and the BCR is closed
this month. New xtty software to acquire and parse data is launched. The
change does not affect instrument basic operation; however the down time
due to frequent imbedded Linux computer malfunctioning is eliminated.

**March 2004**: We discontinue regular wavelength calibration with HgCd
Oriel calibrator. The wavelength stability of RSS105 is very good and
wavelength check using Fraunhofer lines is implemented in data
processing.

**June 2004**: Portable Calibrator is sent to Colorado and New York for
UV calibrator comparison. In July and August only Licor calibrations are
performed. After the Portable Calibrator's return, its fuse had to be
replaced. No changes in calibrator irradiance were noticed.

**September 2004**: Shadowbanding does not shadow correctly. Combo board
replacement cures the problem after 3 weeks of troubleshooting.
Consequently, only the total horizontal spectra are available for
September 2004.

**September 2004**: Closer analysis of calibration data shows a growth
of nonlinearity in radiometric response during the first three months
since deployment. The nonlinearity is characterized from data of every
successful calibration event. New accounting for the nonlinearity
algorithm to process data is developed. All data since the deployment
are being recalculated.

**April-June 2005**: Shadowbanding does not shadow correctly in
afternoons. Motor replacement fixes the problem. In the following
periods due to incorrect shading no direct nor diffuse are reported:

All day bad shading during: \[04/20/05, 05/03/05\]

Bad shading from 1h before noon: \[05/03/05, 05/26/05\]

All day bad shading: \[05/27/05, 05/31/05\]

All day bad shading: \[06/01/05, 06/03/05\]

Bad shading from 1h before noon: \[06/04/05, 06/16/05\]

Good all day with caution: \[06/17/05, 06/28/05\]

### User Manual

For installation and operating instructions, see **7.4.4 Additional
Documentation**

### Routine and Corrective Maintenance Documentation

This section is not applicable to this instrument.

### Software Documentation

All software used in RSS operation and processing is internally
documented. The source files are available. All data files have ample
preambles and headers.

### Additional Documentation

At <http://www.arm.gov/publications/tech_reports/handbooks/rss/> various
additional documents can be found. The list of documents is in the file
AboutFilesInThisDir.doc. The documents are divided in five
subdirectories: manuals/, presentations/, publications/, reports/ and
stmeetings/. The following files can be found there:

SUBDIRECTORY=manuals\\

+---------------------------+------------------------------------------+
| FILE NAME                 | CONTENT                                  |
+---------------------------+------------------------------------------+
| Ins                       | Instructions for Using Li-Cor and Oriel  |
| tructionLicorOrielRSS.pdf | Spectral Calibrator with RSS             |
+---------------------------+------------------------------------------+
| InstructionPortCalRSS.pdf | Instructions for Using Portable          |
|                           | Calibrator with RSS                      |
+---------------------------+------------------------------------------+
| RSS105                    | RSS algebra and noise                    |
| SignalNoise_Oct04_1pk.pdf |                                          |
+---------------------------+------------------------------------------+
| RSSAlogithmsDiagram.pdf   | Diagrams of algorithms used in RSS data  |
|                           | processing                               |
+---------------------------+------------------------------------------+
| Rss1024Manual.pdf         | RSS/UVRSS-1024 Rotating Shadowband       |
|                           | Spectroradiometer Installation and User  |
|                           | Guide                                    |
|                           |                                          |
|                           | *Version 2.1* (YES, Inc.)                |
+---------------------------+------------------------------------------+
| UserInfo(21).pdf          | USING the RSS, low-level firmware        |
|                           | command info UPDATED 06-06-2001 By L.    |
|                           | Harrison, ASRC, SUNY at Albany           |
+---------------------------+------------------------------------------+
| rss105CosCor_Aug04pk.pdf  | Cosine correction in rss105              |
+---------------------------+------------------------------------------+

SUBDIRECTORY=presentations\\

  --------------------------------------- --------------------------------------
  FILE NAME                               CONTENT

  RSSkied_AerosolsWGBoulder2005.pdf       P. Kiedron, "RSS: stability,
                                          calibration, Langley correction,
                                          aerosols OD", Aerosols Working Group,
                                          Boulder, CO, 2005

  RSSkied_IRF_WGAnnapolis2005.pdf         P. Kiedron, "On RSS status", IRF
                                          Working Group, Annapolis, MD, 2005

  RSSkied_IRF_WGSantaBarbara2004.pdf      P. Kiedron, "Rotating Shadowband
                                          Spectroradiometer" , IRF Working
                                          Group, Santa Barbara, CA, 2004

  RSSkied_InstrMentrWGBillings2005.pdf    P. Kiedron, "RSS Mentor Presentation",
                                          Instrument Mentor Working Group,
                                          Billings, OK, 2005

  RSSkied_STM_IRFWGDaytonaBeach2005.pdf   P. Kiedron, "RSS history and current
                                          status", IRF Working Group, Daytona
                                          Beach, FL, 2005
  --------------------------------------- --------------------------------------

SUBDIRECTORY=publications\\

+--------------------+-------------------------------------------------+
| FILE NAME          | CONTENT                                         |
+--------------------+-------------------------------------------------+
| ASE                | C. A. Gueymard, "PREDICTION AND VALIDATION OF   |
| S2006_Gueymard.pdf | CLOUDLESS SHORTWAVE IRRADIANCE FOR HORIZONTAL,  |
|                    | TILTED, OR TRACKING RECEIVERS", Solar 2006      |
|                    | Conference, American Solar Energy Society,      |
|                    | Denver, CO (July 2006)                          |
+--------------------+-------------------------------------------------+
| ApplO              | Piotr W. Kiedron, Joseph J. Michalsky, Jerry L. |
| pt1999_Kiedron.pdf | Berndt, and Lee C. Harrison, "Comparison of     |
|                    | spectral irradiance standards used to calibrate |
|                    | shortwave radiometers and spectroradiometers",  |
|                    | Appl.Opt. 38, pp.2432-2439, 1999                |
+--------------------+-------------------------------------------------+
| GR                 | Lee Harrison, Mark Beauharnois, Jerry Berndt,   |
| L1999_Harrison.pdf | Peter Kiedron, Joseph Michalsky, Qilong Min,    |
|                    | "The Rotating Shadowband Spectroradiometer      |
|                    | (RSS) at SGP", J. Geophys. Res. 108: 4424,      |
|                    | 2003.                                           |
+--------------------+-------------------------------------------------+
| GRL                | J. Michalsky, M. Beauharnois, J. Berndt, L.     |
| 1999_Michalsky.pdf | Harrison, P. Kiedron, and                       |
|                    |                                                 |
|                    | Q. Min, "O2-O2 absorption band identification   |
|                    | based on optical depth spectra of the visible   |
|                    | and near-infrared", Geophys. Res. Lett. 26,     |
|                    | 1581-1584, 1999                                 |
+--------------------+-------------------------------------------------+
| GRL1999_Min.pdf    | Qilong Min and Lee Harrison, "Joint statistics  |
|                    | of photon path length and cloud optical depth", |
|                    | Geophys. Res. Lett. 26, 1425-1428, 1999         |
+--------------------+-------------------------------------------------+
| GRL1999_Schmid.pdf | B. Schmid, J. Michalsky, R. Halthore, M.        |
|                    | Beauharnois, L. Harrison, J. Livingston, P.     |
|                    | Russell, B. Holben, T. Eck, A. Smirnov,         |
|                    | "Comparison of Aerosol Optical Depth from Four  |
|                    | Solar Radiometers During the Fall 1997 ARM      |
|                    | Intensive Observation Period", Geophys. Res.    |
|                    | Lett. 26, 2725-2728, 1999                       |
+--------------------+-------------------------------------------------+
| GRL2000_Mlawer.pdf | Mlaver , E.J., S.A. Clough, Brown, P.D., L.     |
|                    | Harrison, J. Michalsky, P. Kiedron, and T.R.    |
|                    | Shippert, Comparison of Spectral Direct and     |
|                    | Diffuse Solar Irradiance Measurements and       |
|                    | Calculations for Cloud-Free Conditions,         |
|                    | Geophys. Res. Lett., 27, 2653-2656, 2000        |
+--------------------+-------------------------------------------------+
| G                  | Kiedron, P., Berndt, J. Michalsky, J.Harrison,  |
| RL2003_Kiedron.pdf | L., Column water vapor from diffuse irradiance, |
|                    | Geophys. Res. Lett.  Vol. 30, No. 11, 1565,     |
|                    | 2003                                            |
+--------------------+-------------------------------------------------+
| J                  | Kiedron, P., J. Michalsky, B. Schmid, D.        |
| GR2001_Kiedron.pdf | Slater, J. Berndt, L. Harrison, P. Racette, E.  |
|                    | Westwater and Y. Han, A Robust Retrieval of     |
|                    | Water Vapor Column in Dry Arctic Conditions     |
|                    | Using the Rotating Shadowband                   |
|                    | Spectroradiometer, , J. Geophys. Res. 106,      |
|                    | 24,007-24,016,2001                              |
+--------------------+-------------------------------------------------+
| JGR                | Michalsky, J.J., Q. Min, P.W. Kiedron, D.W.     |
| 2001_Michalsky.pdf | Slater, and J.C. Barnard, A Differential        |
|                    | Technique to Retrieve Column Water Vapor Using  |
|                    | Sun Radiometry, J. Geophys. Res., 106, D15,     |
|                    | 17,433-17,442. 2001                             |
+--------------------+-------------------------------------------------+
| JGR2001_Min.pdf    | Qilong Min, Lee C. Harrison, Eugene E.          |
|                    | Clothiaux, "Joint statistics of photon path     |
|                    | length and cloud optical depth: Case studies",  |
|                    | J. Geophys. Res, 106, 7375-7385, 2001           |
+--------------------+-------------------------------------------------+
| JGR2003_Min.pdf    | Qilong Min and Eugene E. Clothiaux, "Photon     |
|                    | path length distributions inferred from         |
|                    | rotating shadowband spectrometer measurements   |
|                    | at the Atmospheric Radiation Measurements       |
|                    | Program Southern Great Plains site", J.         |
|                    | Geophys. Res, 108, NO. D15, 4465,               |
|                    | doi:10.1029/2002JD002963, 2003                  |
+--------------------+-------------------------------------------------+
| JG                 | S. M. Gianelli, B. E. Carlson and A. A. Lacis,  |
| R2005_Gianelli.pdf | "Aerosol retrievals using rotating shadowband   |
|                    | spectroradiometer data", J. Geophys. Res, 110,  |
|                    | D05203, doi:10.1029/2004JD005329, 2005          |
+--------------------+-------------------------------------------------+
| SPIE02_4           | Kiedron, P.W., L. Harrison, J.J. Michalsky,     |
| 815_13_kiedron.pdf | Jr., J. Schlemmer, and J.L. Berndt, "Data and   |
|                    | Signal Processing of Rotating Shadowband        |
|                    | Spectroradiometer (RSS) Data", Proc. SPIE 4815, |
|                    | pp.51-57, 2002                                  |
+--------------------+-------------------------------------------------+

SUBDIRECTORY=reports\\

  --------------------------------- ------------------------------------------
  FILE NAME                         CONTENT

  ETSpectraComparison_Feb1306.pdf   P. Kiedron, "Comparison of several
                                    extraterrestrial irradiances", February
                                    13, 2006

  RSSDataSGPtillMay2003.pdf         Data availability from RSS102 and RSS103
                                    prototypes

  RssPredeploy2003.pdf              P. Kiedron, "RSS Acceptance Tests and
                                    Pre-deployment Characterization", November
                                    17, 2003

  RssSGP1st6months2003.pdf          P. Kiedron, "RSS Performance Evaluation
                                    During First Six Months Since Its
                                    Deployment", November 17, 2003

  rss&mfrsr_Dir2DifRatio.pdf        P. Kiedron, "Comparison of direct to
                                    diffuse ratio from RSS and MFRSR",
                                    December 13, 2005
  --------------------------------- ------------------------------------------

SUBDIRECTORY=stmeetings\\

  ------------------------- --------------------------------------------------
  FILE NAME                 CONTENT

  RSS_ARM2000Kiedron.pdf    P. Kiedron, J. Berndt, J. Michalsky, Q. Min, D.
                            Slater, "Robust retrieval of water vapor at NSA
                            using rotating shadowband spectroradiometer
                            (RSS)", ARM Science Team Meeting, 2000 (poster)

  RSS_ARM2001Harrison.pdf   L. Harrison, J. Berndt, P. Kiedron, J. Michalsky,
                            Q. Min, J. Schlemmer, "The Solar Spectrum 360 to
                            1050 nm from Rotating Shadowband Spectroradiometer
                            (RSS) at the Southern Great Plains Site" , ARM
                            Science Team Meeting, 2001 (poster)

  RSS_ARM2001Kiedron1.pdf   P. Kiedron, K. Berndt, L. Harrison, J. Michalsky,
                            Q. Min, "Column Water Vapor From Diffuse
                            Irradiance", ARM Science Team Meeting, 2001
                            (poster)

  RSS_ARM2001Kiedron2.pdf   P. Kiedron, "Spectral irradiance per interval of
                            equal solar flux: convenient spectral grid for
                            atmospheric radiation measurement and modeling"
                            ARM Science Team Meeting, 2001 (poster)

  RSS_ARM2001Mlawer.pdf     E. J. Mlawer, J. S. Delamere, C. J. Scott, and S.
                            A. Clough , L. C. Harrison, J. J. Michalsky, and
                            P. W. Kiedron , H. W. Barker, T. R. Shippert,
                            "Comparison Between RSS Measurements and
                            LBLRTM/CHARTS Calculations for Clear and Cloudy
                            Conditions", ARM Science Team Meeting 2001,
                            (proceedings)

  RSS_ARM2003Kiedron.pdf    P. Kiedron, J. Berndt, E. Yager, J. Schlemmer, L.
                            Harrison, and J. Michalsky, "Acceptance testing
                            and characterization of the VIS-RSS slated for
                            permanent deployment at the SGP site", ARM Science
                            Team Meeting, 2003 (poster)

  RSS_ARM2005Kiedron.pdf    P. Kiedron, and J. Schlemmer, "Rotating Shadowband
                            Spectroradiometer (RSS) at SGP: Performance Data
                            Processing and Value Added Products", ARM Science
                            Team Meeting, 2005 (poster)

  RSS_ARM2006Kiedron.ppt    Peter Kiedron, and Jim Schlemmer, "Spectrally
                            resolved shortwave flux at ARM: History and the
                            present status of RSS", ARM Science Team Meeting,
                            2006 (poster)
  ------------------------- --------------------------------------------------

## Glossary

See the [ARM Glossary](http://www.arm.gov/about/glossary.stm).

## Acronyms

ASRC: Atmospheric Sciences Research Center

BCR: baseline change request

CCD: charge-coupled device

DQ: Data Quality

FOV: field-of-view

FWHM: Full Width at Half Maximum

MFRS: muti-filter rotating shadowband radiometer

NIST: National Institute of Standards and Technology

NSA: North Slope of Alaska

RSS: rotating shawdowband spectroradiometer

SGP: Southern Great Plains

SZA: Sun Zenith Angle

UV: ultraviolet

Also see the [ARM Acronyms and
Abbreviations](http://www.arm.gov/about/acronyms.stm).

## Citable References

Gianelli, S.M., B. E. Carlson and A. A. Lacis, "Aerosol retrievals using
rotating shadowband spectroradiometer data", *J. Geophys. Res*, **110**,
D05203, doi:10.1029/2004JD005329, 2005

Harrison, L., P. Kiedron, J. Berndt, and J. Schlemmer. 2003.
"Extraterrestrial Solar Spectrum 360--1050 nm from Rotating Shadowband
Spectroradiometer Measurements at the Southern Great Plains (ARM) Site."
*J. Geophys. Res*. **108**:4424.

Kiedron, P.,.J. Berndt, J. Michalsky, and L.Harrison. 2003. "Column
Water Vapor from Diffuse Irradiance." *Geophys. Res. Lett.* **30**:1565.

Kiedron, P., and J. Michalsky. 2003. "Measurement errors in diffuse
irradiance with non-Lambertian radiometers." *International J. Remote
Sensing* **24**:237-247.

Kiedron, P.W., L. Harrison, J.J. Michalsky, Jr., J. Schlemmer, and J.L.
Berndt. 2002. "Data and Signal Processing of Rotating Shadowband
Spectroradiometer (RSS) Data." *Proc. SPIE* **4815**:58-72.

Kiedron, P., J. Michalsky, B. Schmid, D. Slater, J. Berndt, L. Harrison,
P. Racette, E. Westwater, and Y. Han. 2001. "A Robust Retrieval of Water
Vapor Column in Dry Arctic Conditions Using the Rotating Shadowband
Spectroradiometer." *J. Geophys. Res.* **106**:24,007-24,016.

Michalsky, J.J., Q. Min, P.W. Kiedron, D.W. Slater, and J.C. Barnard.
2001. "A Differential Technique to Retrieve Column Water Vapor Using Sun
Radiometry." *J. Geophys. Res*.**106**(D15):17,433-17,442.

Min, Q.L., L.C. Harrison, and E. E. Clothiaux. 2001. "Joint Statistics
of Photon Pathlength and Cloud Optical Depth: Case studies." *J.
Geophys. Res.***106**:7375-7386.

Mlawer, E.J., S.A. Clough, P.D. Brown, L. Harrison, J. Michalsky, P.
Kiedron, and T.R. Shippert. 2000. "Comparison of Spectral Direct and
Diffuse Solar Irradiance Measurements and Calculations for Cloud-Free
Conditions." *Geophys. Res. Lett*. **27**:2653-2656.

Harrison, L., M. Beauharnois, J. Berndt, P. Kiedron, J. Michalsky, and
Q. Min. 1999. "The Rotating Shadowband Spectroradiometer (RSS) at SGP."
*Geophys. Res. Lett.* **26**:1715-1718.

Kiedron, P.W., J.J. Michalsky, J.L. Berndt, and L.C. Harrison. 1999.
"Comparison of Spectral Irradiance Standards Used to Calibrate Shortwave
Radiometers and Spectroradiometers." *Appl. Optics* **38**:2432‑2439.

Michalsky, J., M. Beauharnois, J. Berndt, L. Harrison, P. Kiedron, and
Q. Min. 1999. "O2-O2 Absorption Band identification Based on Optical
Depth Spectra of the Visible and Near-Infrared." *Geophys. Res. Lett*.
**26**:1581-1584.

Min, Q.L., and L. Harrison. 1999. "Joint Statistics of Photon Pathlength
and Cloud Optical Depth." *Geophys. Res. Lett*. **26**:1425-1428.

Schmid, B., J. Michalsky, R. Halthore, M. Beauharnois, L. Harrison, J.
Livingston, P. Russell, B. Holben, T. Eck, and A. Smirnov. 1999.
"Comparison of Aerosol Optical Depth from Four Solar Radiometers During
the Fall 1997 ARM Intensive Observation Period." *Geophys. Res.
Lett*. **26**:2725-2728.

Harrison, L., J.Michalsky, and J. Berndt. 1994. "Automated Multifilter
Rotating Shadow-Band Radiometer: An Instrument for Optical Depth and
Radiation Measurements." *Appl. Optics* **33**:5118-5125.

Harrison, L., and J. Michalsky. 1994. "Objective Algorithms for the
Retrieval of Optical Depths from Ground-Based Measurements." *Appl.
Optics*** 33**:5126-5132.