38a) Location of Streamwise Vorticity Current.pdf
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The estimated location of the well-developed SVC for the Moore, Oklahoma EF5 supercell on May 20, 2013, as determined by radar analysis from this study.
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4) Data Gathered For Seven Key Elements of Tornadogenesis.pdf
After analyzing the RFD occlusion, each storm was examined in detail to identify as many characteristics as possible for the 208 high-end tornadic supercells.
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6) Salyersville, KY Tornadic Supercell on March 2, 2012 - FFD, RFD, Tornado, ...
The supercell that produced the EF3 at Salyersville, Kentucky on March 2, 2012. The RFD boundary is purple and occlusion downdraft is encircled in maroon just southeast of the tornado. The nose of the occlusion downdraft is circled in blue just east-northeast of the tornado. Davies-Jones 2006, Markowski 2002, Lee et al. 2011, 2012 explain more about the occlusion downdraft.
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By the end of the project, the total amount of time to analyze the 208 supercells was about 1,500 hours. The following seven categories were considered the most important for each supercell, although much more data was collected.
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Estimated locations for the RFD boundary (blue) and FFD boundary (purple) for six notable high-end tornadic supercells. These supercells were at peak organization with the inflection point washed out.
6b) Reflectivity Boundary Position Estimate.pdf
Estimate of RFD boundary position (black) using the reflectivity image for Moore, Oklahoma on May 10, 2010. For every RFD boundary estimate, both reflectivity and base velocity were used together, but one was chosen as primary.
6c) Schematic of a Classic Rear Flank Downdraft.pdf
A schematic showing the rear flank downdraft of a tornadic supercell. The RFD occlusion or tornado is at the center of rotational convergence within the RFD. The curved dashed line is the outline of the hook echo. The white area is inflow to the updraft. Gray indicates relatively warm downdraft outflow. An unstable RFD is favorable for tornadogenesis. A couple hundred meters above the surface, winds generally turn south-southwest or southwesterly in the area south of the hook. Graphic obtained from Markowski et al. 2002.
6d) Base Velocity Estimate Overlaid on Reflectivity Base Velocity RFD Boundar...
An example showing the location of the RFD occlusion associated with the Moore, Oklahoma EF5 tornado on May 20, 2013. Base velocity (right) was used as primary to draw the RFD boundary. This location in black was super-imposed onto reflectivity (left). Even though base velocity was the primary indicator for the estimate, reflectivity also shows the RFD boundary well.
7) Estimated Tornado Start Location Relative To RFD Boundary Location For 208...
The distribution of tornadoes relative to the RFD boundary near the tornado start time. 201 of the 208 tornado start locations (96.6%) were more than a quarter nautical mile to the west of the RFD boundary. Seven of the 208 cases (3.4%) were located near the RFD boundary, with three of the seven (1.4%) located on the RFD boundary itself.
8) Tornado Start Location Frequency Relative To RFD Boundary Position For 208...
Contoured estimate of tornado start location relative to the position of the RFD boundary for 208 high-end tornadic supercells. The highest tornado incidence occurred 1.65 nautical miles west and 1.07 nautical miles south of the RFD boundary.
8a) Tornado Start Location Frequency Relative To RFD Boundary Position For 20...
Estimated tornado start locations relative to the RFD boundary for the first and second half of the dataset (left), and east and west of the Mississippi River (middle). The distribution of points is shown for the reflectivity and base velocity scans (right), depending upon which one was used as the primary indicator.
9) EF5 Tornado Frequency Relative To RFD Boundary and EF4-EF5 Tornado Frequen...
Frequency of EF4-EF5 tornadoes (left) and EF5 tornadoes (right), relative to the position of the RFD boundary.
10) Hypothesis - Critical Role of the RFD Surge, Schematic Created and Modifi...
A schematic showing the process of tornadogenesis involving an RFD surge beginning just over 13 minutes before the tornado start time. The RFD surge creates the inflow channel, as the RFD surge impinges on the inflow sector. This likely induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. The tornado forms after the RFD occlusion matures beneath the low-level mesocyclone, most often in the RFD’s northeast quadrant.
10a) Schematic of RFD Surging Beneath Mesocyclone with Rapid Intensification ...
RFD boundary surges northeastward toward the forward flank. As the RFD boundary impinges on the supercell’s inflow sector, an inflow channel is created. This induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. Also, restriction within the inflow channel causes the RFD occlusion to rapidly deepen as air is evacuated upward through the mesocyclone at a faster rate than can be replaced below. The tornado forms after the RFD occlusion matures beneath the low-level meso, most often in the RFD’s northeast quadrant. The descending reflectivity core (DRC) is in dark gray, which wraps around the RFD occlusion near the tornado start time (see Part 2).
11) RFD Surge Identification Method.pdf
An RFD surge was found for all 208 cases. The following method was used to identify the start and end points of the RFD surge, and to measure the RFD surge’s speed relative to the supercell’s speed.
First, the case was loaded and studied for about 15 minutes. The tornado start location was marked. Then, the RFD boundary location was estimated at high confidence times before and after the tornado start time. The examination paid close attention to the movement of precipitation behind the RFD boundary. Four questions listed below, were asked in order to determine when the RFD surge started and ended.
1) When did the precipitation gradient, just behind the RFD boundary, begin to accelerate relative to the storm’s movement?
2) When did the precipitation gradient, just behind the RFD boundary, obtain a bowed or curved appearance?
3) When did the precipitation gradient, just behind the RFD boundary, reach the forward flank?
4) When did the precipitation gradient, just behind the RFD boundary, decelerate relative to the storm’s movement?
Reflectivity data were used exclusively to determine when the RFD surge began and ended. The RFD surge was considered a time period when the leading edge of precipitation, just behind the RFD boundary, moved at a speed faster than the supercell’s speed. This involved an acceleration and then deceleration of the leading edge of precipitation.
11a) RFD Surge Analysis - Sibley, Iowa EF4 Tornado on June 25, 2010.pdf
RFD surge analysis for the Sibley, Iowa EF4 tornado on June 25, 2010. A cell merger ongoing in panel 1, instigates the RFD surge. The RFD surge starting point (panel 2) and ending point (panel 6), are marked. During the RFD surge, the reflectivity structure bulges and rapidly expands (panel 3 and 4). A bowing shape develops in panel 5. The RFD surge ends when it reaches the forward flank (panel 6).
12) Average RFD Surge Times Relative To Tornado Start Time For All 208 Superc...
Sorted distribution of RFD surge storm relative speed for all 208 supercells. The average RFD surge storm relative speed ranged from just under two knots to just over 20 knots. The RFD’s primary role during tornadogenesis is to move the RFD boundary toward the FFD boundary, in order to create an inflow channel. A fast storm relative speed is not necessary to accomplish this task.
13) RFD Surge Type 1 (66.3 Percent) Rozel, KS EF4 - 5-19-2013.pdf
Type 1 RFD surge (at right), in which the low-level mesocyclone is initially above the RFD. During the RFD surge, the RFD boundary moves toward the supercell’s forward flank. The RFD occlusion develops and matures, which is followed by tornado formation in the RFD occlusion. The tornado most often forms in the northeast quadrant of the RFD.
For the Rozel, Kansas EF4 tornado on May 19, 2013 (at right), a prominent cell merger started the RFD surge. The mesocyclone was located to the west of the RFD boundary (panel 1). The cell merger caused an enhanced downdraft to move southeast, creating a long pendant (panel 2). The RFD occlusion developed at the pendant’s southeast end. The tornado formed as the RFD boundary surged northeastward toward the forward flank. This created a narrow inflow channel (panel 3 and 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
14) RFD Surge Type (30.3 Percent) Fackler, AL EF4 - 4-27-2011.pdf
Type 2 RFD surge (at right), in which the RFD surge is initially ahead of the RFD boundary. The RFD boundary moves underneath the low-level mesocyclone and then away toward the forward flank. The RFD occlusion develops and matures after the low-level mesocyclone has been undercut. This is followed by tornado formation within the RFD occlusion.
For the Fackler, Alabama EF4 tornado on April 27, 2011 (to right), the RFD surge was instigated by cell mergers to the southwest of the RFD boundary. The RFD surge was very strong, with a 117 knot max outbound noted in panel two. The inflow channel became narrow as the RFD boundary pushed toward the forward flank (panel 3). Reflectors quickly disappear around the new tornado (panel 4), likely due to absorption by the rapidly strengthening tornado. 300 meter ground-relative flow is estimated based on cell movement and outflow.
15) RFD Surge Type (3.4 Percent) Ravanna, KS EF3 - 5-24-2016.pdf
Type 3 RFD surge (at right), in which the low-level mesocyclone is initially ahead of the RFD boundary. The RFD boundary surges toward the supercell’s forward flank, and to the center of the low-level mesocyclone. An RFD occlusion forms on the RFD boundary, underneath the low-level mesocyclone. The tornado develops within the RFD occlusion, on the RFD boundary, eventually moving southwestward into the RFD.
For the Ravanna, Kansas EF3 tornado on May 24, 2016 (at right), the mesocyclone was initially to the east of the RFD boundary. The RFD surge was instigated by outflow associated with cell mergers west of the boundary (panel 2). As the RFD surged toward the forward flank, the RFD occlusion developed on the RFD boundary (panel 2 and 3). Then, the tornado formed in the RFD occlusion (panel 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
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An example showing the Goldsby, Oklahoma EF4 tornado on May 24, 2011, in which the RFD was disrupted by a northward-moving wave. First, a left-moving supercell from north Texas approached the Goldsby supercell at near 65 nautical miles per hour. Outflow associated with the cell merger enhances vertical vorticity, causing the tornado to strengthen and reach peak intensity (panel 2). After the cell merger, a northward-moving wave associated with the left-mover, hit the Goldsby supercell’s RFD. The back edge of the RFD retreated northward (panels 4, 5 and 6), and eventually the backed flow associated with the northward-moving wave pushed the flanking line precipitation away from the mesocyclone (panels 7 and 8). This disrupted the RFD causing the tornado to dissipate.
17) EF3 Forms After 2nd RFD Surge Undercuts Low-level Meso at Hillsboro, ND o...
An example showing the Hillsboro, North Dakota EF3 tornadic supercell on August 27, 2016, in which there were two RFD surges. The first RFD surge did not produce a tornado, while the second did. The first RFD surge pushed southward and did not undercut the low-level mesocyclone. Veered flow at 700 mb and a lack of cell mergers were limiting factors, keeping the first RFD surge to the west of the low-level meso. The second RFD surge pushed eastward, undercutting the low-level meso. The second RFD surge was aided by cell outflow and cell mergers during the 15 minutes preceding the tornado. Veered low to mid-level flow, associated with northwest flow aloft, can contribute to a problem in which a supercell’s RFD surge takes place too far west. When this happens, it can be difficult for the RFD to undercut the low-level mesocyclone. This problem makes tornadogenesis more unlikely in summer.
18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado ...
During the cell merger analysis, all 208 cases were examined twice. The first examination pass identified cell mergers that occurred closer to the tornado start time. Within this first pass, clustering within the distribution was found at two time periods. The first was found to occur just a few minutes prior to the tornado start time. A second was found further out in time, generally between five and ten minutes prior to the tornado. During the first examination, it was observed that another cell merger was commonly occurring more than 10 minutes prior to the tornado start time. And this cell merger was often happening just before the start of the RFD surge. As a result, a second pass through the 208 cases was completed to identify cell mergers further out before the tornado start time. The cell merger that was identified during the second pass was called cell merger one, while the two cell mergers that were identified during the first pass were called cell merger two and three. After all the analysis was done, a cell merger two was found in more cases than a cell merger one. This is because a cell merger midway through the tornadogenesis process was slightly more common than a cell merger near the beginning of the tornadogenesis process. The first and second examinations were completely independent of each other, which revealed more detail concerning the distribution.
Using the three periods of cell merger clustering, average times prior to the tornado start time were computed. The 208 case average of those times are listed below, with the number of cases identified for each time, and the percent of occurrence listed in Table 1.
19) Location of 77 Cell Mergers That Instigated RFD Surges Relative To Pendan...
The locations of cell merger one for 77 cell mergers relative to the pendant, that likely instigated RFD surges prior to high-end tornadogenesis from June 5, 2010 to March 15, 2012.
Mites,Slug,Snail_Infesting agricultural crops.pdf
Order : Trombidiformes (Acarina) Class : Arachnida
Mites normally feed on the undersurface of the leaves but the symptoms are more easily seen on the uppersurface.
Tetranychids produce blotching (Spots) on the leaf-surface.
Tarsonemids and Eriophyids produce distortion (twist), puckering (Folds) or stunting (Short) of leaves.
Eriophyids produce distinct galls or blisters (fluid-filled sac in the outer layer)
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Estimated locations for the RFD boundary (blue) and FFD boundary (purple) for six notable high-end tornadic supercells. These supercells were at peak organization with the inflection point washed out.
6b) Reflectivity Boundary Position Estimate.pdf
Estimate of RFD boundary position (black) using the reflectivity image for Moore, Oklahoma on May 10, 2010. For every RFD boundary estimate, both reflectivity and base velocity were used together, but one was chosen as primary.
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A schematic showing the rear flank downdraft of a tornadic supercell. The RFD occlusion or tornado is at the center of rotational convergence within the RFD. The curved dashed line is the outline of the hook echo. The white area is inflow to the updraft. Gray indicates relatively warm downdraft outflow. An unstable RFD is favorable for tornadogenesis. A couple hundred meters above the surface, winds generally turn south-southwest or southwesterly in the area south of the hook. Graphic obtained from Markowski et al. 2002.
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An example showing the location of the RFD occlusion associated with the Moore, Oklahoma EF5 tornado on May 20, 2013. Base velocity (right) was used as primary to draw the RFD boundary. This location in black was super-imposed onto reflectivity (left). Even though base velocity was the primary indicator for the estimate, reflectivity also shows the RFD boundary well.
7) Estimated Tornado Start Location Relative To RFD Boundary Location For 208...
The distribution of tornadoes relative to the RFD boundary near the tornado start time. 201 of the 208 tornado start locations (96.6%) were more than a quarter nautical mile to the west of the RFD boundary. Seven of the 208 cases (3.4%) were located near the RFD boundary, with three of the seven (1.4%) located on the RFD boundary itself.
8) Tornado Start Location Frequency Relative To RFD Boundary Position For 208...
Contoured estimate of tornado start location relative to the position of the RFD boundary for 208 high-end tornadic supercells. The highest tornado incidence occurred 1.65 nautical miles west and 1.07 nautical miles south of the RFD boundary.
8a) Tornado Start Location Frequency Relative To RFD Boundary Position For 20...
Estimated tornado start locations relative to the RFD boundary for the first and second half of the dataset (left), and east and west of the Mississippi River (middle). The distribution of points is shown for the reflectivity and base velocity scans (right), depending upon which one was used as the primary indicator.
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Frequency of EF4-EF5 tornadoes (left) and EF5 tornadoes (right), relative to the position of the RFD boundary.
10) Hypothesis - Critical Role of the RFD Surge, Schematic Created and Modifi...
A schematic showing the process of tornadogenesis involving an RFD surge beginning just over 13 minutes before the tornado start time. The RFD surge creates the inflow channel, as the RFD surge impinges on the inflow sector. This likely induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. The tornado forms after the RFD occlusion matures beneath the low-level mesocyclone, most often in the RFD’s northeast quadrant.
10a) Schematic of RFD Surging Beneath Mesocyclone with Rapid Intensification ...
RFD boundary surges northeastward toward the forward flank. As the RFD boundary impinges on the supercell’s inflow sector, an inflow channel is created. This induces a pressure drop due to the Bernoulli Effect, which strengthens the RFD occlusion. Also, restriction within the inflow channel causes the RFD occlusion to rapidly deepen as air is evacuated upward through the mesocyclone at a faster rate than can be replaced below. The tornado forms after the RFD occlusion matures beneath the low-level meso, most often in the RFD’s northeast quadrant. The descending reflectivity core (DRC) is in dark gray, which wraps around the RFD occlusion near the tornado start time (see Part 2).
11) RFD Surge Identification Method.pdf
An RFD surge was found for all 208 cases. The following method was used to identify the start and end points of the RFD surge, and to measure the RFD surge’s speed relative to the supercell’s speed.
First, the case was loaded and studied for about 15 minutes. The tornado start location was marked. Then, the RFD boundary location was estimated at high confidence times before and after the tornado start time. The examination paid close attention to the movement of precipitation behind the RFD boundary. Four questions listed below, were asked in order to determine when the RFD surge started and ended.
1) When did the precipitation gradient, just behind the RFD boundary, begin to accelerate relative to the storm’s movement?
2) When did the precipitation gradient, just behind the RFD boundary, obtain a bowed or curved appearance?
3) When did the precipitation gradient, just behind the RFD boundary, reach the forward flank?
4) When did the precipitation gradient, just behind the RFD boundary, decelerate relative to the storm’s movement?
Reflectivity data were used exclusively to determine when the RFD surge began and ended. The RFD surge was considered a time period when the leading edge of precipitation, just behind the RFD boundary, moved at a speed faster than the supercell’s speed. This involved an acceleration and then deceleration of the leading edge of precipitation.
11a) RFD Surge Analysis - Sibley, Iowa EF4 Tornado on June 25, 2010.pdf
RFD surge analysis for the Sibley, Iowa EF4 tornado on June 25, 2010. A cell merger ongoing in panel 1, instigates the RFD surge. The RFD surge starting point (panel 2) and ending point (panel 6), are marked. During the RFD surge, the reflectivity structure bulges and rapidly expands (panel 3 and 4). A bowing shape develops in panel 5. The RFD surge ends when it reaches the forward flank (panel 6).
12) Average RFD Surge Times Relative To Tornado Start Time For All 208 Superc...
Sorted distribution of RFD surge storm relative speed for all 208 supercells. The average RFD surge storm relative speed ranged from just under two knots to just over 20 knots. The RFD’s primary role during tornadogenesis is to move the RFD boundary toward the FFD boundary, in order to create an inflow channel. A fast storm relative speed is not necessary to accomplish this task.
13) RFD Surge Type 1 (66.3 Percent) Rozel, KS EF4 - 5-19-2013.pdf
Type 1 RFD surge (at right), in which the low-level mesocyclone is initially above the RFD. During the RFD surge, the RFD boundary moves toward the supercell’s forward flank. The RFD occlusion develops and matures, which is followed by tornado formation in the RFD occlusion. The tornado most often forms in the northeast quadrant of the RFD.
For the Rozel, Kansas EF4 tornado on May 19, 2013 (at right), a prominent cell merger started the RFD surge. The mesocyclone was located to the west of the RFD boundary (panel 1). The cell merger caused an enhanced downdraft to move southeast, creating a long pendant (panel 2). The RFD occlusion developed at the pendant’s southeast end. The tornado formed as the RFD boundary surged northeastward toward the forward flank. This created a narrow inflow channel (panel 3 and 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
14) RFD Surge Type (30.3 Percent) Fackler, AL EF4 - 4-27-2011.pdf
Type 2 RFD surge (at right), in which the RFD surge is initially ahead of the RFD boundary. The RFD boundary moves underneath the low-level mesocyclone and then away toward the forward flank. The RFD occlusion develops and matures after the low-level mesocyclone has been undercut. This is followed by tornado formation within the RFD occlusion.
For the Fackler, Alabama EF4 tornado on April 27, 2011 (to right), the RFD surge was instigated by cell mergers to the southwest of the RFD boundary. The RFD surge was very strong, with a 117 knot max outbound noted in panel two. The inflow channel became narrow as the RFD boundary pushed toward the forward flank (panel 3). Reflectors quickly disappear around the new tornado (panel 4), likely due to absorption by the rapidly strengthening tornado. 300 meter ground-relative flow is estimated based on cell movement and outflow.
15) RFD Surge Type (3.4 Percent) Ravanna, KS EF3 - 5-24-2016.pdf
Type 3 RFD surge (at right), in which the low-level mesocyclone is initially ahead of the RFD boundary. The RFD boundary surges toward the supercell’s forward flank, and to the center of the low-level mesocyclone. An RFD occlusion forms on the RFD boundary, underneath the low-level mesocyclone. The tornado develops within the RFD occlusion, on the RFD boundary, eventually moving southwestward into the RFD.
For the Ravanna, Kansas EF3 tornado on May 24, 2016 (at right), the mesocyclone was initially to the east of the RFD boundary. The RFD surge was instigated by outflow associated with cell mergers west of the boundary (panel 2). As the RFD surged toward the forward flank, the RFD occlusion developed on the RFD boundary (panel 2 and 3). Then, the tornado formed in the RFD occlusion (panel 4). 300 meter ground-relative flow is estimated based on cell movement and outflow.
16) Northward-moving Wave Disrupts RFD and EF4 Tornado near Goldsby, OK on Ma...
An example showing the Goldsby, Oklahoma EF4 tornado on May 24, 2011, in which the RFD was disrupted by a northward-moving wave. First, a left-moving supercell from north Texas approached the Goldsby supercell at near 65 nautical miles per hour. Outflow associated with the cell merger enhances vertical vorticity, causing the tornado to strengthen and reach peak intensity (panel 2). After the cell merger, a northward-moving wave associated with the left-mover, hit the Goldsby supercell’s RFD. The back edge of the RFD retreated northward (panels 4, 5 and 6), and eventually the backed flow associated with the northward-moving wave pushed the flanking line precipitation away from the mesocyclone (panels 7 and 8). This disrupted the RFD causing the tornado to dissipate.
17) EF3 Forms After 2nd RFD Surge Undercuts Low-level Meso at Hillsboro, ND o...
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18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado ...
During the cell merger analysis, all 208 cases were examined twice. The first examination pass identified cell mergers that occurred closer to the tornado start time. Within this first pass, clustering within the distribution was found at two time periods. The first was found to occur just a few minutes prior to the tornado start time. A second was found further out in time, generally between five and ten minutes prior to the tornado. During the first examination, it was observed that another cell merger was commonly occurring more than 10 minutes prior to the tornado start time. And this cell merger was often happening just before the start of the RFD surge. As a result, a second pass through the 208 cases was completed to identify cell mergers further out before the tornado start time. The cell merger that was identified during the second pass was called cell merger one, while the two cell mergers that were identified during the first pass were called cell merger two and three. After all the analysis was done, a cell merger two was found in more cases than a cell merger one. This is because a cell merger midway through the tornadogenesis process was slightly more common than a cell merger near the beginning of the tornadogenesis process. The first and second examinations were completely independent of each other, which revealed more detail concerning the distribution.
Using the three periods of cell merger clustering, average times prior to the tornado start time were computed. The 208 case average of those times are listed below, with the number of cases identified for each time, and the percent of occurrence listed in Table 1.
19) Location of 77 Cell Mergers That Instigated RFD Surges Relative To Pendan...
The locations of cell merger one for 77 cell mergers relative to the pendant, that likely instigated RFD surges prior to high-end tornadogenesis from June 5, 2010 to March 15, 2012.
More from JohnChrisBroyles (20)
6a) RFD-FFD Boundary Locations For Six Well-organized HIgh-end Supercells.pdf
6a) RFD-FFD Boundary Locations For Six Well-organized HIgh-end Supercells.pdf
6c) Schematic of a Classic Rear Flank Downdraft.pdf
6c) Schematic of a Classic Rear Flank Downdraft.pdf
6d) Base Velocity Estimate Overlaid on Reflectivity Base Velocity RFD Boundar...
6d) Base Velocity Estimate Overlaid on Reflectivity Base Velocity RFD Boundar...
7) Estimated Tornado Start Location Relative To RFD Boundary Location For 208...
7) Estimated Tornado Start Location Relative To RFD Boundary Location For 208...
8) Tornado Start Location Frequency Relative To RFD Boundary Position For 208...
8) Tornado Start Location Frequency Relative To RFD Boundary Position For 208...
8a) Tornado Start Location Frequency Relative To RFD Boundary Position For 20...
8a) Tornado Start Location Frequency Relative To RFD Boundary Position For 20...
9) EF5 Tornado Frequency Relative To RFD Boundary and EF4-EF5 Tornado Frequen...
9) EF5 Tornado Frequency Relative To RFD Boundary and EF4-EF5 Tornado Frequen...
10) Hypothesis - Critical Role of the RFD Surge, Schematic Created and Modifi...
10) Hypothesis - Critical Role of the RFD Surge, Schematic Created and Modifi...
10a) Schematic of RFD Surging Beneath Mesocyclone with Rapid Intensification ...
10a) Schematic of RFD Surging Beneath Mesocyclone with Rapid Intensification ...
11a) RFD Surge Analysis - Sibley, Iowa EF4 Tornado on June 25, 2010.pdf
11a) RFD Surge Analysis - Sibley, Iowa EF4 Tornado on June 25, 2010.pdf
12) Average RFD Surge Times Relative To Tornado Start Time For All 208 Superc...
12) Average RFD Surge Times Relative To Tornado Start Time For All 208 Superc...
13) RFD Surge Type 1 (66.3 Percent) Rozel, KS EF4 - 5-19-2013.pdf
13) RFD Surge Type 1 (66.3 Percent) Rozel, KS EF4 - 5-19-2013.pdf
14) RFD Surge Type (30.3 Percent) Fackler, AL EF4 - 4-27-2011.pdf
14) RFD Surge Type (30.3 Percent) Fackler, AL EF4 - 4-27-2011.pdf
15) RFD Surge Type (3.4 Percent) Ravanna, KS EF3 - 5-24-2016.pdf
15) RFD Surge Type (3.4 Percent) Ravanna, KS EF3 - 5-24-2016.pdf
16) Northward-moving Wave Disrupts RFD and EF4 Tornado near Goldsby, OK on Ma...
16) Northward-moving Wave Disrupts RFD and EF4 Tornado near Goldsby, OK on Ma...
17) EF3 Forms After 2nd RFD Surge Undercuts Low-level Meso at Hillsboro, ND o...
17) EF3 Forms After 2nd RFD Surge Undercuts Low-level Meso at Hillsboro, ND o...
18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado ...
18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado ...
19) Location of 77 Cell Mergers That Instigated RFD Surges Relative To Pendan...
19) Location of 77 Cell Mergers That Instigated RFD Surges Relative To Pendan...
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Tetranychids produce blotching (Spots) on the leaf-surface.
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Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
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Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
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Mechanics:- Simple and Compound Pendulum
a compound pendulum is a physical system with a more complex structure than a simple pendulum, incorporating its mass distribution and dimensions into its oscillatory motion around a fixed axis. Understanding its dynamics involves principles of rotational mechanics and the interplay between gravitational potential energy and kinetic energy. Compound pendulums are used in various scientific and engineering applications, such as seismology for measuring earthquakes, in clocks to maintain accurate timekeeping, and in mechanical systems to study oscillatory motion dynamics.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
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Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
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Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...
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SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆