# Presentation: 652203

## Instantaneous Radiative Flux (IRF) Working Group Activities - 2006

- Contributors
- Christine Chiu, Chuck Long, Joe Michalsky, Qilong Min, Eli Mlawer, Tom Stoffel, Dave Turner, Andy Vogelmann, Ed Westwater

## IRF Structure

- Three Primary IRF Focus Groups

- _Instrumentation_ Chuck Long

- _Atmospheric/Surface Properties and Modeling _
- Bob Ellingson & Joe Michalsky

- _3-D RT_
- Andy Vogelmann

- Overarching Groups

## IRF 2005 Workshop

- November 2005- Annapolis, MD jointly with Cloud Properties WG
- Focused on:
- reports on recent IRF science activities
- identifying unmet scientific needs
- discussing planned and potential IOPS/campaigns
- developing instrumentation priorities for science needs

## Major Discussion Areas

- CLOWD [**Clouds with Low Optical (Water) Depth]**
- NSA H2O Vapor Measurements
- Longwave Radiation Measurements - Broadband and AERI
- Oxygen A-Band and RSS Issues
- IRF high-altitude IOP [RHUBC - Radiative Heating in Underexplored Bands]

## CLOWD Update[Clouds with Low Optical (Water) Depth]

- Paper submitted to BAMS (Jan 2006)
- Outlines magnitude of problem
- Illustrates ARM’s approach
- 90/150 GHz MWR on order; delivery May 2006
- IOP planning / coordination
- CLASIC, COPS/AMF
- Analysis of Pt. Reyes data
- Extensive dataset of low LWP clouds
- Currently analyzing MWR, NFOV, MFRSR, AERI; will include cloud radar, MWRP, and MODIS

- Dave Turner

**Notes:**
Update of CLOWD activities: Presented by Bob Ellingson during 2006 ARM STM.

CLOWD leaders: Dave Turner and Andy Vogelmann

Main accomplishment: Submission of a paper to BAMS that details the importance of optically thin clouds that contain liquid water (typically with LWPs < 100 g/m2, even though these clouds might not be technically considered optically thin).  The paper also demonstrates the large differences among state-of-the-art retrieval methods for an “easy” case study (single layer, warm, overcast liquid water cloud), and how we can begin to understand the strengths / weaknesses of each algorithm.

Other accomplishments:

  Jim Liljegren has reviewed several options, and has purchased a 90 / 150 GHz microwave radiometer from Radiometer Physics GmbH.  Discussions are underway as to where to deploy this sensor initially.

  Vogelmann and Turner are both taking active roles in the planning and coordination of both the CLASIC (summer 2007 at SGP site)  and COPS/AMF (spring-fall 2007 in Southern Germany) IOPs in order to accomplish some CLOWD goals during these experiments.

  The AMF deployment to Pt. Reyes, California, has resulted in a large collection of data from low liquid water path clouds.  These data are being analyzed extensively by many in the IRF/Cloud Properties group to improve our understanding of the strengths/weaknesses of our current retrieval algorithms and to develop new algorithms, which hopefully will lead to an automated ARM product to provide the microphysical properties of these clouds 24/7 at all ARM sites.

## Pt. Reyes CLOWD Analysis: Statistics

- Data from 1 July – 31 August 2005

- Preliminary analysis

**Notes:**
Summary graph showing how the different retrieval algorithms compare relative to each other.  The box-and-whisker plots show the median (thick black horizontal line), the 25th and 75th quartiles (colored boxes), and the 5th and 95th percentiles (whiskers).

Left panel: comparison of effective radius retrieved from the MIXCRA (Turner’s AERI algorithm) and the MFRSR (Qilong Min).  The MIXCRA has a slight high bias (~0.8 um) relative to the MFRSR.

Center panel: Comparison of cloud optical depths from the MIXCRA, MFRSR, and 2-channel NFOV (Christine Chiu and Sasha Marshak’s algorithm).  MIXCRA underestimates the optical depth relative to both the MFRSR and NFOV (consistent with the effective radius), while the NFOV is higher than the MRFSR.

Right panel: Comparison of LWP from MIXCRA and 3 different MWR retrievals.
    MWRlos is the standard MWR retrieval product, which uses site-dependent monthly retrieval coefficients
    MWRret2 is a new MWR product that uses site-independent retrieval coefficients derived from surface obs of T/P/U
    MWRretP is a new MWR product that performs a physical-iterative retrieval, but this is only available near sonde times
The two new MWR products will soon be released as a VAP.

## Retrieving Cloud Optical Depth from Zenith Radiance Observations; Examples from Pt. Reyes ARM Mobile Facility

***Christine Chiu, UMBC/JCET***
***Alexander Marshak, GSFC***
***Yuri Knyazikhin, Boston University***
***Warren Wiscombe, GSFC***
***James Barnard, PNNL***
***John Schmelzer, PNNL***

## Measure zenith radiance at red & NIR channels from the 2NFOV at the AMF Pt. Reyes deployment

**Retrieve cloud optical depth from these radiances**
**Compare retrievals with those from MFRSR and MWR**

## Submitted to JAOT,10-14-05

*V. Mattioli, *_*E. R. Westwater*_*, D. Cimini, J. S. Liljegren, B. M. Lesht, S. I. Gutman, and F. J. Schmidlin** *

**Radiosonde and ground-based remotely sensed PWV data from the **
**2004 North Slope  of Alaska Arctic Winter Radiometric Experiment: Implications for the US Arctic Climate Record**

-  Radiosondes launched during the NSA-WVIOP04
-     experiment (Vaisala RS90, NWS-VIZ, Snow White)
-  Radiosonde quality control
-  Analyses of temperature and relative humidity
-     measurements: **Significant biases in T and RH**
**    ****and implications for US Arctic Climate Record**
-  Comparison of PWV from MWRP, GPS, MWR, and
-      RAOB’s
-  PWV day-night differences
-  A powerful tool: 22.235 GHz Tb observations

##  Relative Comparisons of the New ARM/NREL Pyrgeometer Calibrations: 1) Using Four PIR Calibration Equations, 2) Using Two Reference Black Bodies, 3) Broader Perspective, and 4) Recommendations

- E. Dutton
- I.  Reda
- T. Stoffel
- J. Michalsky
- ARM/IRF
- Annapolis, MD
-  3 Nov 2005

## The new ARM/NREL pyrgeometer calibration uses a newly derived calibration transfer equation (Reda et al, 2002 J. Atmos Solar-Terres. Phys.) and a new reference blackbody.

Previous ARM pyrgeometer calibration used  Cox&Albrecht xfer equation with an incorrect dome factor and the Eppley commercial BB

Some anomalies have appeared after the implementation of the new ARM calibration causing a closer investigation of the new and old ARM pyrgeometer calibrations

- Previous ARM pyrgeometer calibration used  Cox&Albrecht xfer equation with an incorrect dome factor and the Eppley commercial BB
**Some anomalies have appeared after the implementation of the new ARM calibration causing a closer investigation of the new and old ARM pyrgeometer calibrations**

## 2004 LW QME indicated that the PIRs were in error by ~10-12 W/m2

- Surface temperature (oC)

- Irradiance difference (W/m2)

- 2004 LW QME indicated that the PIRs were in error by ~10-12 W/m2

## Pyrgeometer Calibrations& Field Measurements

- Updated Review and Recommendations to the ARM Program
- Tom Stoffel
- 27 March 2006
- 16th Science Team Meeting
- Albuquerque, New Mexico

- IRF - STM Breakout 28 March 2006

**Notes:**
Not sure who wants their name on this presentation.  Please let me know once you’ve seen the whole file...

## Important Points

- ARM needs ***accurate*** pyrgeometer calibration method ***traceable*** to the World Infrared Standard Group (WISG)
- The ***WISG*** was established by PMOD/WRC in 2004 based on ***IPASRC I & II*** (Low-temperature blackbody sources + Absolute Sky-scanning Radiometer) + Outdoor pyrgeometer comparisons
***Characterizations*** of pyrgeometer calibration methods ***continue*** at EPLAB, NOAA, NREL, and PMOD
***Outdoor characterization*** of pyrgeometers with respect to a recognized reference is ***essential*** for determining the best calibration method

**Notes:**
Put the important stuff first!  These are the key points I hope we can agree upon and communicate to the audience.

## Shortwave Clear Sky Closure Study

- 2003 Aerosol IOP

- J. J. Michalsky

**Notes:**
The solid green columns are the model direct offsets, the solid blue are the model diffuse offsets from the measurements. The hatched are the root-mean-square differences from the measurements. The units are W/m-sq with the mean direct 761.5 and the mean diffuse 108.6 W/m-sq. The measurement uncertainty is about 4 W/m-sq for the diffuse and about 10 W/m-sq for the direct. Therefore, all results within the measurement uncertainty without considering model uncertainty. This is about the same results as previous papers got for direct and is much better for the diffuse, which now does not have model diffuse statistically significantly higher than measurements. 

Improved results probably because asymmetry parameters are lower than typically assumed and measured spectral albedo used for every case rather than equivalent broadband albedo.

## Photon path distribution spectrometer

**Qilong Min and Peter Kiedron**
**ASRC, State University of New York at Albany **

## IRF Recommendations to STEC

- _CLOWD_ (several)
- _NSA_ - again recommend 4 soundings per day and deployment of a 183 GHz MWR
- _Data Quality Issues_ - we see a need for a comprehensive reevaluation of manner by which data are quality controlled - from BCR’s to implementation to inter-device relationships.
- Encourage the measurement of vertical profiles of radiative flux divergence during CLASIC
- Recommend a _high altitude IOP_ to study important, but unexplored, portions of the electromagnetic spectrum (RHUBC whitepaper available)

**Notes:**
he CLOWD focus group presented a list of priority instrumentation listed below in order of the CLOWD priority.
1.Purchase and deploy 90 GHz microwave radiometers at all sites
2.Increase the sampling rate of the AERIs as per previous recommendations
3.Increase the sampling rate of the MWRs, the details for which are under study
4. Modify the MFRSR to allow better liquid water path (LWP) determinations
5.Purchase a two-channel NFOV instrument and permanently deploy one at the SGP and AMF. Routine calibrations should be part of the deployment. This instrument is in addition to the one already purchased.
6.Deploy a CIMEL on the AMF for 2-NFOV work (post-Niger deployment). (Comments: Even at Goddard after calibrating 2NFOV it is compared with the CIMEL to be sure the measurements are correct.  Another reason is to have simultaneous retrievals of aerosol and cloud properties.)
7.Provide Trishchenko-like BDRF product (0.5 km resolution averaged over 10 days). (Comments:  In its stead, they can use the MODIS BDRF at 1 km resolution averaged over 16 days, and MISR data, if available (although the longer averaging period could miss important temporal variations). 

## Why a High Altitude IOP?

- 	We can not study many important bands from surface observations (SW and LW)

- MLS 0.0 km downwelling spectrum and spectral heating rates

## Why a High Altitude IOP?

- 	At NSA, only a portion of the 20 μm widow opens allowing a peek at long wavelengths

- SAW 0.0 km downwelling spectrum and spectral heating rates

## Why a High Altitude IOP?

- 	Moving to 5 km (i.e., a mountain observatory) opens the 20 μm window and we begin to be able to observe surface-masked regions

- MLS 5.0 km downwelling spectrum and spectral heating rates

## Radiative Heating in Underexplored Bands Campaign (RHUBC)

- Proposed AMF deployment for 2008
- Deployment in very dry location - Atacama Desert, Northern Chile
- Investigate important radiative processes in bands usually opaque from ground
-  Spectral closure studies
-  far infrared (20 - 450 cm-1)
-  new instruments:  FIRST, TAFTS
-  infrared (1350 - 1850 cm-1)
-  near infrared (centers of water vapor bands)

- Eli Mlawer and Dave Turner

## Instrumentation Prioritized Recommendations

- Deploy 90 GHz MWRs at all sites
- Acquire a sky-scanning longwave radiometer
- Add a downward looking MFR instrument on the aerosol aircraft
- Acquire an Oxygen A-band instrument (old)
- Modified MFRSRs for better (LWP) determination
- Two-channel NFOV instrument at SGP and AMF
- Address the correction of the RSS stability
- Add a 1.6 micron channel on NFOV