Satellite Ocean Aerosol Retrieval (SOAR) algorithm extension to S-NPP VIIRS as part of the 'Deep Blue' aerosol project.

The Suomi National Polar-Orbiting Partnership (S-NPP) satellite, launched in late 2011, carries the Visible Infrared Imaging Radiometer Suite (VIIRS) and several other instruments. VIIRS has similar characteristics to prior satellite sensors used for aerosol optical depth (AOD) retrieval, allowing the continuation of space-based aerosol data records. The Deep Blue algorithm has previously been applied to retrieve AOD from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectro-radiometer (MODIS) measurements over land. The SeaWiFS Deep Blue data set also included a SeaWiFS Ocean Aerosol Retrieval (SOAR) algorithm to cover water surfaces. As part of NASA's VIIRS data processing, Deep Blue is being applied to VIIRS data over land, and SOAR has been adapted from SeaWiFS to VIIRS for use over water surfaces. This study describes SOAR as applied in version 1 of NASA's S-NPP VIIRS Deep Blue data product suite. Several advances have been made since the SeaWiFS application, as well as changes to make use of the broader spectral range of VIIRS. A preliminary validation against Maritime Aerosol Network (MAN) measurements suggests a typical uncertainty on retrieved 550nm AOD of order ±(0.03+10%), comparable to existing SeaWiFS/MODIS aerosol data products. Retrieved Ångström exponent and fine mode AOD fraction are also well-correlated with MAN data, with small biases and uncertainty similar to or better than SeaWiFS/MODIS products.

Observations of the Interaction and Transport of Fine Mode Aerosols with Cloud and/or Fog in Northeast Asia from Aerosol Robotic Network (AERONET) and Satellite Remote Sensing.

Analysis of sun photometer measured and satellite retrieved aerosol optical depth (AOD) data has shown that major aerosol pollution events with very high fine mode AOD (>1.0 in mid-visible) in the China/Korea/Japan region are often observed to be associated with significant cloud cover. This makes remote sensing of these events difficult even for high temporal resolution sun photometer measurements. Possible physical mechanisms for these events that have high AOD include a combination of aerosol humidification, cloud processing, and meteorological co-variation with atmospheric stability and convergence. The new development of Aerosol Robotic network (AERONET) Version 3 Level 2 AOD with improved cloud screening algorithms now allow for unprecedented ability to monitor these extreme fine mode pollution events. Further, the Spectral Deconvolution Algorithm (SDA) applied to Level 1 data (L1; no cloud screening) provides an even more comprehensive assessment of fine mode AOD than L2 in current and previous data versions. Studying the 2012 winter-summer period, comparisons of AERONET L1 SDA daily average fine mode AOD data showed that Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing of AOD often did not retrieve and/or identify some of the highest fine mode AOD events in this region. Also, compared to models that include data assimilation of satellite retrieved AOD, the L1 SDA fine mode AOD was significantly higher in magnitude, particularly for the highest AOD events that were often associated with significant cloudiness.

Evaluation of NASA Deep Blue/SOAR aerosol retrieval algorithms applied to AVHRR measurements.

The Deep Blue (DB) and Satellite Ocean Aerosol Retrieval (SOAR) algorithms have previously been applied to observations from sen-sors like the Moderate Resolution Imaging Spectroradiometers (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) to provide records of mid-visible aerosol optical depth (AOD) and related quantities over land and ocean surfaces respectively. Recently, DB and SOAR have also been applied to Ad-vanced Very High Resolution Radiometer (AVHRR) observations from several platforms (NOAA11, NOAA14, and NOAA18), to demonstrate the potential for extending the DB and SOAR AOD records. This study provides an evaluation of the initial version (V001) of the resulting AVHRR-based AOD data set, including validation against Aerosol Robotic Network (AERONET) and ship-borne observations, and comparison against both other AVHRR AOD Research (GESTAR), Universities Space Research Association. records and MODIS/SeaWiFS products at select long-term AERONET sites. Although it is difficult to distil error characteristics into a simple expression, the results suggest that one standard deviation confidence intervals on retrieved AOD of ±(0.03+15%) over water and ±(0.05+25%) over land represent the typical level of uncertainty, with a tendency towards negative biases in high-AOD conditions, caused by a combination of algorithmic assumptions and sensor calibration issues. Most of the available validation data are for NOAA18 AVHRR, although performance appears to be similar for the NOAA11 and NOAA14 sensors as well.

Cross-calibration of S-NPP VIIRS moderate resolution reflective solar bands against MODIS Aqua over dark water scenes.

The Visible Infrared Imaging Radiometer Suite (VIIRS) is being used to continue the record of Earth Science observations and data products produced routinely from National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. However, the absolute calibration of VIIRS's reflected solar bands is thought to be biased, leading to offsets in derived data products such as aerosol optical depth (AOD) as compared to when similar algorithms are applied to different sensors. This study presents a cross-calibration of these VIIRS bands against MODIS Aqua over dark water scenes, finding corrections to the NASA VIIRS Level 1 (version 2) reflectances between approximately +1 % and -7 % (dependent on band) are needed to bring the two into alignment (after accounting for expected differences resulting from different band spectral response functions), and indications of relative trending of up to ^0.35 % per year in some bands. The derived calibration gain corrections are also applied to the VIIRS reflectance and then used in an AOD retrieval, and are shown to decrease the bias and total error in AOD across the midvisible spectral region compared to the standard VIIRS NASA reflectance calibration. The resulting AOD bias characteristics are similar to those of NASA MODIS AOD data products, which is encouraging in terms of multisensor data continuity.

Modification of lipid acyl groups by serum deprivation does not affect phorbol ester-induced differentiation of human leukemia cells.

12-O-Tetradecanoylphorbol-13-acetate (TPA), a potent tumor promoter, can induce differentiation of human promyelocytic leukemia cells grown in a serum-free environment. Removal of serum produces altered acyl group composition of cellular phospholipids, most notably, marked decreases in the polyunsaturated fatty acid content. Although higher amounts of TPA are required to induce differentiation in serum-free cell populations, induction assessed by morphological and enzymatic markers in similar to the "macrophage-like' differentiated state reported for cells grown in a serum-rich medium.

Chromosome aberrations in relation to radiation dose following partial-body exposures in three populations.

Structural chromosome aberrations were evaluated in peripheral blood samples obtained from three populations exposed to partial-body irradiation. These included 143 persons who received radiotherapy for enlarged thymus glands during infancy and 50 sibling controls; 79 persons irradiated for enlarged tonsils and 81 persons surgically treated for the same condition during childhood; and 77 women frequently exposed as young adults to fluoroscopic chest X rays during lung collapse treatment for tuberculosis (TB) and 66 women of similar ages treated for TB with other therapies. Radiation exposures occurred 30 and more years before blood was drawn. Doses to active bone marrow averaged over the entire body were 21, 6, and 14 cGy for the exposed thymic, tonsil, and TB subjects, respectively. Two hundred metaphases were scored for each subject, and the frequencies of symmetrical (stable) and asymmetrical (unstable) chromosome aberrations were quantified in 97,200 metaphases. Cells with stable aberrations were detected with greater frequency in the irradiated subjects compared with nonirradiated subjects in all three populations, and an overall test for an association between stable aberrations and partial-body ionizing radiation was highly significant (P less than 0.001). We found no evidence that radiation-induced aberrations varied by age at exposure. These data show that exposure of children or young adults to partial-body fractionated radiation can result in detectable increased frequencies of stable chromosome aberrations in circulating lymphocytes 30 years later, and that these aberrations appear to be informative as biological markers of population exposure.

Cumulative genetic damage in hematopoietic stem cells in a patient with a 40-year exposure to alpha particles emitted by thorium dioxide.

Thorotrast, a colloidal suspension of the long-lived radionuclide, thorium-232, was widely used as a radiographic contrast medium for several decades. Due to the poor excretion of the sol, however, Thorotrast would deposit in the liver, bone marrow and other tissue, and patients would receive alpha-particle irradiation for life. To gauge the cumulative genetic damage to hematopoietic stem cells due to chronic exposure to alpha particles, we conducted a multi-end-point evaluation in a 72-year-old man who had been administered a 32-ml bolus of Thorotrast during cerebral angiography performed over 40 years ago in 1950. Peripheral T lymphocytes were cultured to quantify the frequencies and cellular distributions of asymmetrical and symmetrical types of chromosome aberrations in first-division metaphases and micronuclei in cytokinesis-arrested interphase II cells. Aberrations were scored using classical chromosome group analysis methods and chromosome painting techniques. Assays of glycophorin-A (GPA) mutations in red blood cells were also performed to obtain a relative measurement of damage sustained by the erythroid stem cell population. Results revealed that approximately 30% of the lymphocytes in this patient contained one or more chromosome aberrations, the majority of which were of the "stable" type. About one-third of the lymphocytes with chromosome damage carried multiple aberrations, suggesting that significant numbers of stem cells survive exposures to alpha-particle radiation that induce complex genomic alterations. Increased frequencies of GPA mutations were observed, demonstrating that genomic damage is also induced in erythroid progenitors. The numbers of micronuclei in lymphocytes were only moderately increased compared to expected values for persons of comparable age, and thus this end point was not useful for quantifying exposure level. Despite the relatively severe burden of somatic cell damage induced by 40 years of internal alpha-particle irradiation, the patient remains surprisingly free of any serious illness.

Chromosome aberrations in lymphocytes from women irradiated for benign and malignant gynecological disease.

Excess leukemias have occurred after partial-body radiotherapy for cervical cancer and benign gynecological disease (BGD). However, the level of risk is nearly the same in both groups, about twofold, despite a tenfold difference in average dose to active bone marrow (8 Gy vs 0.7 Gy, respectively). High-dose cell killing has been postulated as one explanation for this apparent inconsistency. To examine whether chromosome aberration rates observed in lymphocytes many years after exposure might serve as population markers of cancer risk, blood samples were taken from 60 women treated for BGD (34 with radiation) and cytogenetic data compared with previous results from 96 women irradiated for cervical cancer. Remarkably, the rate of stable aberrations, which reflects nonlethal damage in surviving stem cells, was only slightly higher among the cancer patients. Thus the lower-dose regimens to treat benign disorders resulted in much higher aberration yields per unit dose than those for cervical cancer. Assuming that the fraction of cytogenetically aberrant stem cells that survive radiotherapy contributes to the leukemogenic process, these data are then consistent with the epidemiological observations of comparable overall leukemia risks seen in these two irradiated populations. Accordingly, for patient populations given partial-body radiotherapy, stable aberrations at a long time after exposure appear to serve as biomarkers of effective risk rather than as biomarkers of radiation dose received.

Do recorded doses overestimate true doses received by Chernobyl cleanup workers? Results of cytogenetic analyses of Estonian workers by fluorescence in situ hybridization.

Studies of workers who were sent to Chernobyl after the 1986 reactor accident are being conducted to provide a better understanding of the effects of chronic low-dose radiation exposures. A crucial component to these investigations is an accurate assessment of the radiation doses received during the cleanup activities. To provide information on biological measurements of dose, fluorescence in situ hybridization (FISH) with whole-chromosome painting probes has been applied to quantify stable chromosome aberrations (translocations and insertions) among a defined cohort of 4,833 cleanup workers from Estonia. Cytogenetic analysis of 48-h lymphocyte cultures from 118 Estonian cleanup workers (10.3 cGy mean recorded dose; 25 cGy maximum), 29 Estonian population controls and 21 American controls was conducted by three laboratories. More than 258,000 painted metaphases were evaluated. Overall, we observed lower translocation frequencies than has been reported in previous studies using FISH among Chernobyl cleanup workers. In our data, a clear association with increased levels of translocations was seen with increasing age at blood drawing. There was no correlation, however, between aberration frequency and recorded measurements of physical dose or any category of potential high-dose and high-dose-rate exposure such as being sent to Chernobyl in 1986, working on the roof near the damaged nuclear reactor, working in special zones or having multiple tours. In fact, the translocation frequency was lower among the exposed workers than the controls, though not significantly so. To estimate the level of effect that would have been expected in a population of men having an average dose of approximately 10 cGy, blood from six donors was exposed to low-LET radiation, and more than 32,000 metaphases were scored to estimate dose-response coefficients for radiation-induced translocations in chromosome pairs 1, 2 and 4. Based on these results, we estimate that had this group of 118 men received an average whole-body dose of 10-11 cGy, as chronic or acute exposures, an increase in the mean frequency of chromosome translocations of more than 40-65% would have been observed in their lymphocytes compared to findings in nonirradiated controls. In spite of evaluating more than a quarter of a million metaphases, we were unable to detect any increase in the mean, median or range in chromosome aberrations in lymphocyte cultures from a group of Estonian men who took part in the cleanup of the Chernobyl nuclear power site and those who did not. We conclude that it is likely that recorded doses for these cleanup workers overestimate their average bone marrow doses, perhaps substantially. These results are consistent with several negative studies of cancer incidence in Chernobyl cleanup workers and, if borne out, suggest that future studies may not be sufficiently powerful to detect increases in leukemia or cancer, much less distinguish differences between the effects of chronic compared to brief radiation exposures.

Premature separation of centromeres in marrow chromosomes from an untreated patient with acute myelogenous leukemia.

Cytogenetic studies in an untreated patient with acute myelogenous leukemia revealed that greater than 60% of his marrow metaphases had pronounced anomalies in the centromere region. In the least affected chromosomes, the centromere appeared as a nonstaining hole, whereas in the most affected chromosomes, it appeared that the centromere segment had prematurely migrated at right angles to the telomeric portions. The population of mitoses exhibiting premature separation of the centromeres was reduced to virtually none during periods of drug induced remission. Our findings suggest that cytogenetic changes in malignant myeloid cells may be characterized by defects in centromere separation, as well as by alternations in karyotype.

Analysis of mutagen-induced chromosome damage in a primate species (Saguinus oedipus oedipus) at risk for spontaneous adenocarcinoma of the colon.

A high incidence of adenocarcinoma of the colon (greater than 16%) has been observed at necropsy in the South American primate, Saguinus oedipus oedipus (S. oedipus), while the disease has not been found in tamarins of the closely related species, Saguinus fuscicollis spp, housed in the same research colony. Cytogenetic analyses in cultured lymphocytes from 10 S. oedipus and 10 S. fuscicollis illigeri (S. fuscicollis) demonstrated no differences in the average frequencies of spontaneous or mitomycin C (MMC)-induced sister chromatid exchanges (SCEs) between animals of the two species. However, highly significant variability in MMC-induced chromosome lesions was observed between the individual S. oedipus, with one animal exhibiting increased sensitivity for both SCEs and chromosome breakages. At present we do not know the relationship, if any, between increased sensitivity to mutagen-induced cytogenetic lesions in specific S. oedipus tamarins and the increased risk for colon cancer that has been documented in this primate species. However, our cytogenetic findings in this one S. oedipus are similar to data obtained in evaluations of persons with several autosomal recessive conditions in which there is a genetic predisposition for developing malignancies.

Methods for improving the yield and quality of metaphase preparations for FISH probing of human lymphocyte chromosomes.

Procedures are described for the in vitro culture of human lymphocytes, which have been concentrated by density gradient centrifugation, and for a modified slide-making technique for the fixed cells. The method yields improved percentages of mitotic cells which are largely synchronized at harvest. Controlled placement of fixed cells on slides produces well-spread metaphase preparations with little background material to interfere with fluorescence in situ hybridization (FISH) probe procedures. The FISH reagents and microscope scanning time required are minimized by concentrating cells in a defined area of the slide.

Analysis by FISH of the spectrum of chromosome aberrations induced by X-rays in G0 human lymphocytes and their fate through mitotic divisions in culture.

The induction, distribution, and persistence of chromosome aberrations in human lymphocytes exposed to X-rays in G0 were analyzed in 48-, 70-, and 94-hr cultures by conventional metaphase analysis and painting of chromosomes 1, 2, and 4 by FISH. All cells that had been scored by FISH were relocated to determine by differential staining of chromatids whether they had passed through 1, 2, or > or =3 divisions. FISH revealed a dose-dependent induction of stable and unstable aberrations, while chromatid labeling showed mitotic lag caused by irradiation in G0. Relative to their DNA contents, there was a small but significant overrepresentation of chromosome 4 and underrepresentation of chromosome 2 among the aberrations involving chromosomes 1, 2, and 4. FISH slightly underestimated the genomic frequency of unstable aberrations measured by conventional metaphase analysis. There was a slight excess of translocations relative to dicentrics, but the data are compatible with the 1:1 ratio expected from cytogenetic theory. Many of the translocations were apparently incomplete (i.e., nonreciprocal). Incomplete translocations were more frequent at higher X-ray dose and in first division, suggesting that they may be associated with complex damage and are more apt to be lost in mitosis than complete translocations. Among the incomplete translocations, t(Ab) outnumbered t(Ba) -- a difference ascribable to the FISH technique. Aberration frequencies declined as the cells divided in culture. The overall decline in the frequency of aberrant cells (approximately 29% per cell generation) reflects a rapid decline in dicentrics and fragments (approximately 60% per cell generation) and the relative stability of translocations. The frequency of translocation-bearing cells underwent a modest decline in culture (approximately 13% per cell generation).

Higher frequency of chromosome aberrations in late-arising first-division metaphases than in early-arising metaphases after exposure of human lymphocytes to X-rays in G0.

PURPOSE: To determine whether metaphases arising at different times after mitogen stimulation of G0 lymphocytes differ in frequencies of X-ray-induced chromosome aberrations. MATERIALS AND METHODS: Human G0 lymphocytes from peripheral blood exposed to 0, 1.5 or 3.0 Gy X-rays were stimulated to divide with the mitogen phytohaemagglutinin (PHA). First-division metaphases were distinguished from second and third divisions by chromatid labelling with 5-bromodeoxvuridine (BUdR) and staining with Giemsa or DAPI. Cultures harvested 48, 70 and 94 h after mitogen stimulation were analysed for unstable aberrations on Giemsa-stained slides and for stable and unstable aberrations by fluorescence in situ hvbridization (FISH) with painting probes for chromosomes 1, 2 and 4. RESULTS: Frequencies of aberrations declined at the later culture periods, as expected on the basis of unstable aberrations being lost in mitotic division. Whe n scoring was restricted to firstdivision metaphases, however, aberration frequencies were higher in 94-h cultures than in 48-h cultures. CONCLUSIONS: Frequencies of radiation-induced chromosome aberrations in first-division metaphases increase with culture time after mitogen stimulation. Possible explanations for this finding are a delay of damaged cells in mitogenic response or progression through divisions and heterogeneity among lymphocytes in culture kinetics and radiosensitivity. The data argue against the common assumption that all first-division cells are equivalent as indicators of radiation-induced chromosome aberrations.

Potentiation of bleomycin by the aminothiol WR-1065 in assays for chromosomal damage in G0 human lymphocytes.

The aminothiol radioprotector WR-1065 potentiates the induction of chromosome aberrations and micronuclei by the chemotherapy drug bleomycin in G(0) human lymphocytes. Potentiation by 5 mM WR-1065 was observed at bleomycin concentrations from 0.1 to 100 micrograms/ml in a 2-h treatment. The frequencies of micronuclei induced by bleomycin in the presence of WR-1065 reached that of 500-fold higher concentrations of bleomycin alone. The potential therapeutic implications of these findings are discussed.

Sister-chromatid exchanges in human lymphocytes exposed during Go to four classes of DNA-damaging chemicals.

Human lymphocytes were treated prior to mitogenic stimulation with varying concentrations of 6 cytostatic drugs representing 4 classes of DNA-damaging chemicals. Afterwards the cells were washed to remove residual chemical and cultured in the presence of bromodeoxyuridine for analysis of sister-chromatid exchanges (SCEs). A dose-related increase in SCEs was observed in cells exposed during Go to the alkylating chemicals mitomycin C, chlorambucil, and thiotepa, while significant increases in SCEs were not noted in cultures exposed to methotrexate, cytarabine, or bleomycin. These findings suggest that not all classes of clatogenic chemicals which induce SCEs in proliferative cells substituted with BUdR are capable of inducing long-lived lesions in the DNA of Go lymphocytes that can lead to SCE formation.

Long-term responses of rainforest erosional systems at different spatial scales to selective logging and climatic change.

Long-term (21-30 years) erosional responses of rainforest terrain in the Upper Segama catchment, Sabah, to selective logging are assessed at slope, small and large catchment scales. In the 0.44 km(2) Baru catchment, slope erosion measurements over 1990-2010 and sediment fingerprinting indicate that sediment sources 21 years after logging in 1989 are mainly road-linked, including fresh landslips and gullying of scars and toe deposits of 1994-1996 landslides. Analysis and modelling of 5-15 min stream-suspended sediment and discharge data demonstrate a reduction in storm-sediment response between 1996 and 2009, but not yet to pre-logging levels. An unmixing model using bed-sediment geochemical data indicates that 49 per cent of the 216 t km(-2) a(-1) 2009 sediment yield comes from 10 per cent of its area affected by road-linked landslides. Fallout (210)Pb and (137)Cs values from a lateral bench core indicate that sedimentation rates in the 721 km(2) Upper Segama catchment less than doubled with initially highly selective, low-slope logging in the 1980s, but rose 7-13 times when steep terrain was logged in 1992-1993 and 1999-2000. The need to keep steeplands under forest is emphasized if landsliding associated with current and predicted rises in extreme rainstorm magnitude-frequency is to be reduced in scale.

Comparisons of dose-response parameters for radiation-induced acentric fragments and micronuclei observed in cytokinesis-arrested lymphocytes.

We employed cytochalasin B to block cytokinesis in human lymphocytes exposed to 220 kV X-radiation. When 3 micrograms/ml of cytochalasin B was used, most cells escaped the block whereas at 6 micrograms/ml greater than 90% of the mitogen-responsive cells became binucleate. Using the higher concentration of cytochalasin B, we observed a linear-quadratic (i.e. Y = gamma + alpha D + beta D2) dose dependency for X-ray-induced micronuclei (MN) in preparations from three donors. When dose-response parameters were compared with those for total acentrics scored in first division metaphases, we observed no significant differences in estimates of the background (gamma) or linear (alpha) coefficients, but a 2-fold reduction in the beta coefficient for MN. We interpret our data as providing evidence that radiation-induced micronuclei are derived from acentric fragments (AF); that virtually all AF are recovered as MN in binucleate interphase daughter cells at low radiation doses; and that for our data, the relative proportion of AF that will be observed as independent MN decreases by a constant factor of approximately one-half as radiation dose increases.

Cell-cycle-stage specificity of the methotrexate block as resolved by X-ray-induced chromosome damage.

Radiation-induced chromosome aberrations were used as biomarkers to compare G0, mid-G1, and methotrexate (MTX)-arrested lymphocytes. The ratio of chromosome-type to chromatid-type aberrations in MTX-arrested cells was consistent with that predicted when postreplicative chromosomes are exposed to ionizing radiation and supports the premise that MTX arrests cells in late S/G2 of the cell cycle.

Persistence of SCE-inducing lesions after G0 exposure of human lymphocytes to differing classes of DNA-damaging chemicals.

We conducted studies to determine whether cycling human lymphocytes are equally efficient in repairing sister chromatid exchange (SCE)-producing lesions induced by differing classes of DNA-damaging chemicals. Lymphocytes were pulse-treated during G0 with mitomycin C (MMC), N,N',N''-triethylenethiophosphoramide (ThioTEPA), ethylmethanesulfonate (EMS), or cis-diamminedichloroplatinum (cis-DDP). Bromodeoxyuridine (BrdUrd) was added to the 72 hr cultures at 0 hr or at 48 hr after phytohemmagglutinin stimulation. The concentrations of chemicals employed induced a greater than 2-fold increase in SCEs in second-division metaphases from lymphocytes cultured in the presence of BrdUrd for the entire 72 hr. The analysis of SCEs in uniformly harlequinized metaphases from G0-treated lymphocytes cultured in BrdUrd for the terminal 24 hr showed no increase above baseline after exposure to MMC, and intermediate increases above baseline after exposures to ThioTEPA and cis-DDP. However, after G0 treatment with EMS, the observed SCE frequency was consistent with that expected had all DNA lesions persisted and continued to give rise to SCEs during 3 cell cycles. These findings suggest that cycling human lymphocytes are not equally efficient in eliminating SCE-producing lesions after exposure to differing classes of DNA-damaging chemicals.