EXPERIMENT Radiative Heating in UnderExplored Bands Campaign (RHUBC)
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Transcript of EXPERIMENT Radiative Heating in UnderExplored Bands Campaign (RHUBC)
EXPERIMENT Radiative Heating in UnderExplored Bands Campaign (RHUBC)
Period: February 15 – March 15, 2007
Location: ARM NSA, Barrow, Alaska
GOALS
• Comparison of Microwave and Millimeter
wavelength radiometers in deriving PWV and LWP
• Retrieval of Temperature and Humidity Profiles
Remote Sensing of Water Vapor, Cloud Liquid, and Temperature during RHUBC by Microwave and Millimeter Wave Radiometers
E. R. Westwater1,4, D. Cimini2, V. Mattioli3, M. Klein4, V. Leuski4, A. J. Gasiewski1,4 and D. Turner5
1Department of Electrical and Computer Engineering, University of Colorado at Boulder, USA2CETEMPS, University of L’Aquila, L’Aquila, Italy
3Dipartimento di Ingegneria Elettronica e dell'Informazione, Università di Perugia, Perugia, Italy 4Center for Environmental Technology, University of Colorado, USA
5University of Wisconsin, Madison, Wisconsin, USA MOTIVATION
Retrievals of PWV
Fig.1 List of instruments and experimental set-up deployed during RHUBC.
Fig.2 Real time display during RHUBC of GSR Tb data. Note the menu of available choices of available data.
Fig.4 Scatter plot comparisons between the GSR (blue) and the MWR LOS retreivals of PWV compared with RS92 Radiosondes
MWRMWRPGSR
RETRIEVALS OF LWP
Corresponding author: [email protected]
Fig.3 Comparison of PWV retrievals from the MWR LOS, the GSR, and RS92 Sondes on Julian day 65, 2007
ARM Science Team Meeting, March 10-14, 2008, Norfolk, VA
RETRIEVALS OF LWP AND T AND Q PROFILES
CONCLUSIONS
•As a continuation of our 1999 and 2004 NSA experiments, we
participated In RHUBC, where the principal focus was on low amounts
of Precipitable Water Vapor (PWV < 2 mm), and a secondary goal of
small amounts of cloud liquid. Several improvements were made in the
GSR, both in number of frequencies, and performance of selected
channels. The GSR was successfully operated from February 20 to
July 1, 2007.
• PWV retrievals of the GSR compared well with RS92 Radiosondes and yield a relative accuracy of about 5%.• Comparisons of LWP from the GSR, as well as MIXCRA and MWRRET are quite encouraging for LWP > 20 g/m2. The use of the 340 GHz channels is promising for the smaller LWP amount. • Also encouraging are the preliminary 1DVAR retrievals of temperature and specific humidity. Further development will focus on cloud liquid and the complete set of 27 GSR channels.
Instrument Frequencies (GHz) Parameters
ARM Microwave Radiometer (MWR)
23.8, 31.4 PWV, LWP
CET Ground-based Scanning Radiometer (GSR)
50.300, 51.760, 52.625, 53.290, 53.845, 54.400, 54.950, 55.520, 56.025, 56.215, 56.325
T(z), LWP
ARM Microwave Radiometer Profiler (MWRP)
22.235, 23.035 ,23.835, 26.235, 30.000, 51.250, 52.280, 53.850, 54.940, 56.660, 57.290, 58.800
PWV, LWP, T(z)
CET GSR 89 (H & V) LWP
CET GSR 183.31 ± ( 0.55, ± 1.0, ± 3.05, ± 4.7, ± 7.0, ± 12.0, ± 16.0)
PWV
CET GSR 340 (H & V) LWP
CET GSR 380.197 ± ( 4.0, ± 9.0, ± 17.0) PWV
ARM GVR 183.31 ± ( 1,3,7, 14) PWV, LWP
CET GSR 10 m Cloud
ARM AERI 520 -3300 cm-1 Cloud
GSR RETRIEVAL METHOD•A Priori Linear Statistical Retrieval using Tb’s as predictors•Historical data set of Vaisala RS90/RS92 taken at NSA (Substantial QC was necessary)•RTE model based on Liljegren et al. (2005)•Tb’s adjusted to Liljegren et al. 2005 model based on WVIOP_2004 data comparisons•Covariance matrix of experimental errors determined from WVIOP_2004 data
MWR LOS RETRIEVAL METHOD•A priori Linear Statistical Retrieval using τ (optical depth) as predictors.• Monthly values of Mean Radiating Temperature•RTE model based on Liljegren et al. (2005)
CLEAR CONDITIONS FROM VCEIL AND IRT
Fig. 5. Left. Scatter Plots of LWP retrievals from the MWR-LOS (red), MWRRET(blue) and the MIXCRA (BLACK) vs. the GSR. Right: MIXCRA VS. GSR. Note the excellent agreement between MIXCRA and the GSR
Fig. 6. Left:GSR vs. MIXCRA. Right: MIXCRA vs. MWRRET. Note the outliers associated with the MIXCRA in both figures . This could be due to either an algorithm or an AERI hatch problem.
LWP LESS THAN 60 g/m2
In Fig. 6, we showed LWP retrieval for
contents < 60 g/m2. However, on Julian
day 73, there was a significant amount of
liquid shown by the MWR, the GSR, and
the AERI. Unfortunately, the MWRRET
data did not pass quality control and are
not available for this day. We show in
Figs. 7 retrieval comparisons for the
higher liquid amounts.
Fig. 7. Left Retrievals of GSR-MIXCRA. Right: LOS-GSR Fig. 8. 1DVAR retrievals profiles of Temperature and Specific Humidity.
We have recently developed One Dimensional Variational (1D-VAR) retrievals of GSR data.This method is fully physical and is based on the Liljegren et al. (2005)RTE model. It initial guess is theNCEP forecast model, and the algorithm iterates until the residuals are less that the estimated GSRnoise levels. These retrievals use zenith GSR data up to 183.31 GHz.