208 research outputs found
MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Data Sets (Revision 2)
This report provides a short description of the Atmospheric Radiation Measurement (ARM) Climate Research Facility microwave radiometer (MWR) Retrieval (MWRRET) value-added product (VAP) algorithm. This algorithm utilizes a complementary physical retrieval method and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b)
In silico investigations of intratumoral heterogeneous interstitial fluid pressure
Recent preclinical studies have shown that interstitial fluid pressure (IFP) within tumors can be heterogeneous Andersen et al. (2019). In that study tumors of two xenograft models, respectively, HL-16 cervical carcinoma and Panc-1 pancreatic carcinoma, were investigated. Significant heterogeneity in IFP was reported and it was proposed that this was associated with division of tissue into compartments separated by thick connective tissue bands for the HL-16 tumors and with dense collagen-rich extracellular matrix for the Panc-1 tumors. The purpose of the current work is to explore these experimental observations by using in silico generated tumor models. We consider a mathematical multiphase model which accounts for tumor cells, fibroblasts and interstitial fluid. The model has been trained to comply with experimental in vitro results reported in Shieh et al. (2011) which has identified autologous chemotaxis, ECM remodeling, and cell-fibroblast interaction as drivers for invasive tumor cell behavior. The in silico model is informed with parameters that characterize the leaky intratumoral vascular network, the peritumoral lymphatics which collect the fluid, and the density of ECM as represented through the hydraulic conductivity of the interstitial space. Heterogeneous distribution of solid stress may result in heterogeneous compression of blood vessels and, thus, heterogeneous vascular density inside the tumor. To mimic this we expose the in silico tumor to an intratumoral vasculature whose net effect of density of blood vesssels and vessel wall conductivity is varied through a 2D Gaussian variogram constrained such that the resulting IFPs lie within the range as reported from the preclinical study. The in silico cervical carcinoma model illustrates that sparse ECM was associated with uniform intratumoral IFP in spite of heterogeneous microvascular network, whereas compartment structures resulted in more heterogeneous IFP. Similarly, the in silico pancreatic model shows that heterogeneity in the microvascular network combined with dense ECM structure prevents IFP to even out and gives rise to heterogeneous IFP. The computer model illustrates how a heterogeneous invasive front might form where groups of tumor cells detach from the primary tumor and form isolated islands, a behavior which is natural to associate with metastatic propensity. However, unlike experimental studies, the current version of the in silico model does not show an association between metastatic propensity and elevated IFP.publishedVersio
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MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Datasets
This report provides a short description of the Atmospheric Radiation Measurement (ARM) microwave radiometer (MWR) RETrievel (MWRRET) Value-Added Product (VAP) algorithm. This algorithm utilizes complimentary physical and statistical retrieval methods and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b)
ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report
This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution
An architecture for consolidating multidimensional time-series data onto a common coordinate grid
Diffraction-limited near-IR imaging at Keck reveals asymmetric, time-variable nebula around carbon star CIT 6
We present multi-epoch, diffraction-limited images of the nebula around the
carbon star CIT 6 at 2.2 microns and 3.1 microns from aperture masking on the
Keck-I telescope. The near-IR nebula is resolved into two main components, an
elongated, bright feature showing time-variable asymmetry and a fainter
component about 60 milliarcseconds away with a cooler color temperature. These
images were precisely registered (~35 milliarcseconds) with respect to recent
visible images from the Hubble Space Telescope (Trammell et al. 2000), which
showed a bipolar structure in scattered light. The dominant near-IR feature is
associated with the northern lobe of this scattering nebula, and the
multi-wavelength dataset can be understood in terms of a bipolar dust shell
around CIT 6. Variability of the near-IR morphology is qualitatively consistent
with previously observed changes in red polarization, caused by varying
illumination geometry due to non-uniform dust production. The blue emission
morphology and polarization properties can not be explained by the above model
alone, but require the presence of a wide binary companion in the vicinity of
the southern polar lobe. The physical mechanisms responsible for the breaking
of spherical symmetry around extreme carbon stars, such as CIT 6 and IRC+10216,
remain uncertain.Comment: 18 pages, 5 figures (one in color), to appear in the Astrophysical
Journa
Imaging galactic diffuse clouds: CO emission, reddening and turbulent flow in the gas around Zeta Oph
Methods: 12CO emission is imaged in position and position-velocity space
analyzed statistically, and then compared with maps of total reddening and with
models of the C+ - CO transition in H2-bearing diffuse clouds. Results: Around
Zeta Oph, 12CO emission appears in two distinct intervals of reddening centered
near EBV = 0.4 and 0.65 mag, of which < 0.2 mag is background material. Within
either interval, the integrated 12CO intensity varies up to 6-12 K-km/s
compared to 1.5 K-km/s toward Zeta Oph. Nearly 80% of the individual profiles
have velocity dispersions < 0.6 km/s, which are subsonic at the kinetic
temperature derived from H2 toward Zeta Oph, 55 K. Partly as a result, 12CO
emission exposes the internal, turbulent, supersonic (1-3 km/s) gas flows with
especial clarity in the cores of strong lines. The flows are manifested as
resolved velocity gradients in narrow, subsonically-broadened line cores.
Conclusions: The scatter between N(CO) and EBV in global, CO absorption line
surveys toward bright stars is present in the gas seen around Zeta Oph,
reflecting the extreme sensitivity of N(12CO) to ambient conditions. The
two-component nature of the optical absorption toward Zeta Oph is coincidental
and the star is occulted by a single body of gas with a complex internal
structure, not by two distinct clouds. The very bright 12CO lines in diffuse
gas arise at N(H2) ~ 10^21/cm^2 in regions of modest density n(H) ~ 200-500/cc
and somewhat more complete C+-CO conversion. Given the variety of structure in
the foreground gas, it is apparent that only large surveys of absorption
sightlines can hope to capture the intrinsic behavior of diffuse gas.Comment: 2009 A&A, in pres
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ACRF Ingest Software Status: New, Current, and Future - February 2007
The purpose of this report is to provide status of the ingest software used to process instrument data for the Atmospheric Radiation Measurement Program Climate Research Facility (ACRF). The report is divided into 4 sections: (1) for news about ingests currently under development, (2) for current production ingests, (3) for future ingest development plans, and (4) for information on retired ingests
Scattered H-alpha emission from a large translucent cloud G294-24
We study an undocumented large translucent cloud, detected by means of its
enhanced radiation on the SHASSA (Southern H-Alpha Sky Survey Atlas) survey. We
consider whether its excess surface brightness can be explained by light
scattered off the dust grains in the cloud, or whether emission from in situ
ionized gas is required. In addition, we aim to determine the temperature of
dust, the mass of the cloud, and its possible star formation activity. We
compare the observed H-alpha surface brightness of the cloud with predictions
of a radiative transfer model. We use the WHAM (Wisconsin H-Alpha Mapper)
survey as a source for the Galactic H-alpha interstellar radiation field
illuminating the cloud. Visual extinction through the cloud is derived using
2MASS J, H, and K band photometry. We use far-IR ISOSS (ISO Serendipitous
Survey), IRAS, and DIRBE data to study the thermal emission of dust. The LAB
(The Leiden/Argentine/Bonn Galactic HI Survey) is used to study 21cm HI
emission associated with the cloud. Radiative transfer calculations of the
Galactic diffuse H-alpha radiation indicate that the surface brightness of the
cloud can be explained solely by radiation scattered off dust particles in the
cloud. The maximum visual extinction through the cloud is about 1.2mag. The
cloud is found to be associated with 21cm HI emission at a velocity of about -9
km/s. The total mass of the cloud is about 550-1000 solar masses. There is no
sign of star formation in this cloud. The distance of the cloud is estimated
from the Hipparcos data to be about 100 pc
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