Contrail statistical prediction methods are often location specific. To take advantage of the fact that the upper-tropospheric (UT) meteorological conditions that favor "clear-sky outbreaks" of ...persisting contrails, or contrail favored areas (CFAs), tend to be synoptic in scale, a visual UT-map technique to hindcast CFAs has been developed and tested for subregions of the contiguous United States (CONUS) that have high outbreak frequencies in midseason months (January, April, July, and October) of 2000–02. The method compares daily maps with the composite fields for outbreak days (CON) versus nonoutbreak days (NON), and those assessments are evaluated using standard skill measures. Binary logistic regression determines which UT variables are significant predictors, individually and in combination. The reproducibility of the outbreak hindcast results is tested on the same subregions for the corresponding months of 2008–09. The results confirm the importance of UT relative humidity and vertical-motion (omega) map patterns in regional clear-sky outbreaks. Although the hindcast skill is modest, sensitivity tests suggest that the method will be substantially improved when a longer-term climatological dataset of outbreaks becomes available (to increase sample sizes) and with explicit consideration of the synoptic types on CON days. The latter is demonstrated specifically for the southern CONUS in January, where to improve hindcast success one should also consider the vertical wind shear in the upper troposphere, given the importance of the subtropical jet stream in contrail outbreaks there. Further development of the method to improve its skill ultimately should permit its use in combination with existing objective (statistical and physical models) methods of contrail prediction.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
Mild therapeutic hypothermia is argued being beneficial for outcome after cardiac arrest.
Materials and methods
Retrospective analysis of Circulation Improving Resuscitation Care (CIRC) ...trial data to assess if therapeutic cooling to 33 ± 1 °C core temperature had an association with survival. Of 4231 adult, out‐of‐hospital cardiac arrests of presumed cardiac origin initially enrolled, eligibility criteria for therapeutic hypothermia were met by 1812. Logistic regression was undertaken in a stepwise fashion to account for the impact on outcome of each significant difference and for the variable of interest between the groups.
Results
Out‐of‐ and in‐hospital cooled were 263 (15%), only after admission cooled were 230 (13%) and not cooled were 357 (20%) patients. The group cooled out of‐ and in hospital had 98 (37%) survivors as compared to the groups cooled in hospital only 80 (35%) and of those not cooled 68 (19%). After adjusting for known covariates (sex, age, witnessed cardiac arrest, no‐ and low‐flow time, shockable initial rhythm, random allocation, bystander cardiopulmonary resuscitation and percutaneous coronary intervention), the odds ratio for survival comparing no cooling to out‐of‐ plus in‐hospital cooling was 0·53 95% confidence interval (CI): 0·46–0·61, P < 0·001, and comparing to in‐hospital cooling only was 0·67 (95% CI: 0·50–0·89, P = 0·006).
Conclusion
Mild therapeutic hypothermia initiated out of hospital and/or in hospital was associated with improved survival within this secondary analysis of the CIRC cohort compared to no therapeutic hypothermia.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
The potential of condensation trails (contrails) from jet aircraft to affect regional-scale surface temperatures has been debated for years, but was difficult to verify until an opportunity arose as ...a result of the three-day grounding of all commercial aircraft in the United States in the aftermath of the terrorist attacks on 11 September 2001. Here we show that there was an anomalous increase in the average diurnal temperature range (that is, the difference between the daytime maximum and night-time minimum temperatures) for the period 11-14 September 2001. Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails over this period.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Background Guidelines recommend 2 min of CPR after defibrillation attempts followed by ECG analysis during chest compression pause. This pause may reduce the likelihood of return of ...spontaneous circulation (ROSC) and survival. We have evaluated the possibility of analysing the rhythm earlier in the CPR cycle in an attempt to replace immediate pre-shock rhythm analysis. Methods and results The randomized Circulation Improving Resuscitation Care (CIRC) trial included patients with out of hospital cardiac arrest of presumed cardiac aetiology. Defibrillator data were used to categorize ECG rhythms as shockable or non-shockable 1 min post-shock and immediately before next shock. ROSC was determined from end-tidal CO2 , transthoracic impedance (TTI), and patient records. TTI was used to identify chest compressions. Artefact free ECGs were categorized during periods without chest compressions. Episodes without ECG or TTI data or with undeterminable ECG rhythm were excluded. Data were analyzed using descriptive statistics. Of 1657 patients who received 3409 analysable shocks, the rhythm was shockable in 1529 (44.9%) cases 1 min post-shock, 13 (0.9%) of which were no longer shockable immediately prior to next possible shock. Of these, three had converted to asystole, seven to PEA and three to ROSC. Conclusion While a shockable rhythm 1 min post-shock was present also immediately before next possible defibrillation attempt in most cases, three patients had ROSC. Studies are needed to document if moving the pre-shock rhythm analysis will increase shocks delivered to organized rhythms, and if it will increase shock success and survival.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In Part I of this observational study inquiring into the relative influences of “top down” synoptic atmospheric conditions and “bottom up” land surface mesoscale conditions in deep convection for the ...humid lowlands of the Midwest U.S. Central Corn Belt (CCB), the composite atmospheric environments for afternoon and evening periods of convection (CV) versus no convection (NC) were determined for two recent summers (1999 and 2000) having contrasting precipitation patterns and amounts. A close spatial correspondence was noted between composite synoptic features representing baroclinity and upward vertical motion with the observed precipitation on CV days when the “background” (i.e., free atmosphere) wind speed exceeded approximately 10 m s-1at 500 hPa (i.e., “stronger flow”). However, on CV days when wind speeds were <~10 m s-1(i.e., “weaker flow”), areas of increased precipitation can be associated with synoptic composites that are not so different from those for corresponding NC days. From these observations, the presence of a land surface mesoscale influence on deep convection and precipitation is inferred that is better expressed on weaker flow days. Climatically, a likely candidate for enhancing low-level moisture convergence to promote deep convection are the quasi-permanent vegetation boundaries (QPVBs) between the two major land use and land cover (LULC) types of crop and forest that characterize much of the CCB. Accordingly, in this paper the role of these boundaries on summer precipitation variations for the CCB is extracted in two complementary ways: 1) for contrasting flow day types in the summers 1999 and 2000, by determining the spatially and temporally aggregated land surface influence on deep convection from composites of thermodynamic variables e.g., surface lifted index (SLI), level of free convection (LFC), and lifted condensation level (LCL) that are obtained from mapped data of the 6-h NCEP–NCAR reanalyses (NNR), and 0000 UTC rawinsonde ascents; and 2) for summer seasons 1995–2001, from the statistical associations of satellite-retrieved LULC boundary attributes (i.e., length and width) and precipitation at high spatial resolutions.
For the 1999 and 2000 summers (item 1 above), thermodynamic composites determined for V(500) categories having minimal differences in synoptic meteorological fields on CV minus NC (CV NC) days (i.e., weaker flow), show statistically significant increases in atmospheric moisture (e.g., greater precipitable water; lower LCL and LFC) and static instability e.g., positive convective available potential energy (CAPE) compared to NC days. Moreover, CV days for both weaker and stronger background flow have associated subregional-scale thermodynamic patterns indicating free convection at the earth’s surface, supported by a synoptic pattern of at least weakly upward motion of air in the midtroposphere in contrast to NC days.
The possibility that aerodynamic contrasts along QPVBs readily permit air to be lofted above the LFC when the lower atmosphere is moist, thereby assisting or enhancing deep convection on CV days, is supported by the multiyear analysis (item 2 above). In early summer when LULC boundaries are most evident, precipitation on weaker flow days is significantly greater within 20 km of boundaries than farther away, but there is no statistical difference on stronger flow days. Statistical relationships between boundary mean attributes and mean precipitation change sign between early summer (positive) and late summer (negative), in accord with shifts in the satellite-retrieved maximum radiances from forest to crop areas. These phenological changes appear related, primarily, to contrasting soil moisture and implied evapotranspiration differences. Incorporating LULC boundary locations and phenological status into reliable forecast fields of lower-to-midtropospheric humidity and wind speed should lead to improved short-term predictions of convective precipitation in the Corn Belt and also, potentially, better climate seasonal forecasts.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the Midwest U.S. Corn Belt, the 1999 and 2000 summer seasons (15 June–15 September) expressed contrasting spatial patterns and magnitudes of precipitation (1999: dry; 2000: normal to moist). ...Distinct from the numerical modeling approach often used in studies of land surface–climate interactions, a “synoptic climatological” (i.e., stratified composite) approach is applied to observation data (e.g., precipitation, radar, and atmospheric reanalyses) to determine the relative influences of “top-down” synoptic atmospheric circulation (Part I, this paper) and “bottom-up” land surface mesoscale conditions (Part II) on the predominantly convective precipitation variations. Because mesoscale modeling suggests that the freeatmosphere wind speed (“background wind”) regulates the land surface–atmosphere mesoscale interaction, each day’s spatial range of wind speed at 500 hPa V(500) over the Central Corn Belt (CCB) is classified into one of five categories ranging from “weak flow” to “jet maximum.” Deep convective activity (i.e., presence/absence and morphological signature type) is determined for each afternoon and early evening period from the Next Generation Weather Radar (NEXRAD) imagery. Frequencies of the resulting background wind–convection joint occurrence types for the 1999 and 2000 summer seasons are examined in the context of the statistics determined for summers in the longer period of 1996–2001, and also compose categories for which NCEP–NCAR reanalysis (NNR) fields are averaged to yield synoptic composite environments for the two study seasons. The latter composites are compared visually with high-resolution (spatial) composites of precipitation to help identify the influence of top-down climate controls.
The analysis confirms that reduced (increased) organization of radar-indicated deep convection tends to occur with weaker (stronger) background flow. The summers of 1999 and 2000 differ from one another in terms of background flow and convective activity, but more so with respect to the six-summer averages, indicating that a fuller explanation of the precipitation differences in the two summers must be sought in the analysis of additional synoptic meteorological variables. The composite synoptic conditions on convection (CV) days (no convection (NC) days) in 1999 and 2000 are generalized as follows: low pressure incomingfrom the west (high pressure or ridging), southerly (northerly) lower-tropospheric winds, positive (negative) anomalies of moisture in the lower troposphere, rising (sinking) air in the midtroposphere, and a location south of the upper-tropospheric jet maximum (absence of an upper-tropospheric jet or one located just south of the area). Features resembling the “northerly low-level jets” identified in previous studies for the Great Plains are present on some NC-day composites. On CV days the spatial synchronization of synoptic features implying baroclinity increases with increasing background wind speed. The CV and NC composites differ least on days of weaker flow, and there are small areas within the CCB having no obvious association between precipitation elevated amounts and synoptic circulation features favoring the upward motion of air. These spatial incongruities imply a contributory influence of “stationary” (i.e., climatic) land surface mesoscale processes in convective activity, which are examined in Part II.
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The cirrus-level “condensation trails” (contrails) produced by jet aircraft are considered to influence surface climate and its recent changes. To reveal the synoptic atmospheric environments ...typically associated with multiple co-occurrences of contrails occurring in otherwise clear or partly cloudy skies (outbreaks) for the United States, and ultimately to assist in forecasting these events, a composite (i.e., multicase average) “synoptic climatology” at regional scales is developed for the midseason months (January, April, July, October) of 2000–02. The NCEP–NCAR reanalysis data that emphasize upper-troposphere (UT) variables are allied with manually identified outbreaks appearing on satellite Advanced Very High Resolution Radiometer digital data, using a geographic information system. The highest frequencies of outbreaks by far occur in the Midwest (32.6% of all-U.S. total), followed by the Northeast (17.6%) and Southeast (17.2%). In these regions, all of which have a high density of jet air traffic, an additional 2% cirrus cloud coverage from outbreak-related contrails is inferred. Large interannual and interseasonal variations in contrail outbreak frequencies support the role of meteorological variations. For most regions, the outbreak-associated synoptic circulation composite conditions involve UT ridging and a higher and colder tropopause than the climatological average; meridionally enhanced gradients of the UT vertical motion, located between sinking air to the east (in the ridge) and rising air to the west, in advance of a trough; similarly strong gradients of mid–upper-troposphere humidity, comprising dry air located to the east and moist air to the west; and horizontal speed shear ahead of an advancing jet stream. Notwithstanding, there is a geography (i.e., areal differentiation) to contrail outbreak environments: composites for the Northeast suggest an influence of land–sea contrasts on synoptic systems and, therefore, on contrail outbreaks. For the Northwest, there is evident a greater impact of horizontal wind shear contrasted with other regions. The synoptic climatology results are supported by the all-U.S. averages of contrail outbreak UT conditions climate diagnostics (CDNs) previously determined for early–mid-September periods of 1995–2001. Moreover, a comparison of these CDNs with those derived for nearby thick natural clouds, including cirrus, helps to clarify their different synoptic associations: the UT conditions typical of thick clouds represent an intensification of those associated with contrail outbreaks and include the greater upward vertical motion, moister air, and stronger westerly winds characteristic of a trough. Given the location of most contrail outbreaks downstream of multilayered cloud systems, contrails may help to extend the “natural” cirrus and cirrostratus spatial coverage.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The cirrus-level 'condensation trails' (contrails) produced by jet aircraft often occur as sub-regional-scale 'outbreaks' of multiple contrails, suggested as contributing to post ~1965 climate trends ...in parts of the US and Europe. Several previously-developed, satellite-image based contrail spatial inventories for the conterminous US (CONUS) revealed regional-scale differences in frequency. However, the use of such geographically-fixed regions was not ideal for climate studies. As a first step towards determining the potential climate impacts of contrail outbreaks for the CONUS, we develop maps of overlapping (in time, space) outbreak occurrences—'overlaps'— by applying GIS to a recent period (2000–2002) satellite-image derived inventory for mid-season months. The higher-frequency outbreak overlap regions undergo substantial between-season variations in magnitude and extent that reflect an association with upper-tropospheric temperature gradients and winds. Overlap maps generated for additional mid-season months in 2008–2009 indicate the inter-annual variability of the outbreak regionalization. To clarify the role of uppertroposphere synoptic meteorological conditions in contrail outbreak occurrence, we form composites—multi-case averages—for the sub-region of maximum overlap frequency in each midseason month. Regional and seasonal variations in the relative roles of 'thermo-dynamic' (here, temperature, humidity) and 'dynamic' (vertical motion of air, horizontal wind) controls in outbreaks are identified. Last, we demonstrate potential utility of the spatial overlap method by deriving fallseason surface station trends (1951–1993) of sky cover variables for contrasting high versus low contrail and overlap frequency grid cells in the eastern CONUS. These suggest a contrail contribution to recent high-cloud increases, notably for the Midwest.
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Contrails are important in understanding how aviation potentially affects climate change. The commonly used methods for detecting contrails usually only consider the spectral information of the ...image. This study focuses on introducing an object-based method for detecting contrails in AVHRR images. An object-based method utilizes not only the spectral characteristics, but also spatial information to aid in the detection. The results of the experimental study demonstrate that it is practical to use an object-based classification method for contrail detection. Compared with pixel-based classification methods, the accuracy of the results is improved using the object-based method.
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