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Search in: Search Results second seconds Settings Shift Back to top Slide Text Space SUBMIT ALL submit all SUBMIT submit Submit Unmute volume principles of meteorological doppler radar velocity contamination artifacts instructor: andy wood review lesson take your time and review the lesson content provided in this presentation. review lesson technical problems? if you encounter any technical problems with this lesson, please contact the rac team directly by e-mail at: nws.wdtd.rachelp@noaa.gov technical problems? complete the quiz at the end of this lesson, there is an embedded quiz. complete this quiz by selecting the best answer for each question. you need to correctly answer 70% of the quiz questions to receive completion credit in the lms. complete the quiz course completion review lesson review lesson complete the quiz technical problems? technical problems? introduction in order for nws forecasters to receive credit for this course in the nws learning center, you will need to take the following steps rac principles roadmap learning objectives identify the common sources of velocity contamination artifacts identify both the common and alternate signatures associated with velocity artifacts identify the reason why velocity and spectrum width data might have their respective data appearance identify the steps for identifying velocity couplet imposters why velocity contamination matters z srm cc sw velocity contamination causes imposter couplets 1 in 4 low-level velocity couplets may be impacted z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw sidelobe contamination example 0.5 0.9 1.4 1.9 2.4 3.2 4.0 5.1 6.4 8.0 10.1 12.5 15.7 z srm cc sw use slider to adjust tilt z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw z srm cc sw tbss contamination example 0.5 0.9 1.3 1.8 2.4 3.1 4.0 5.1 6.4 8.0 10.0 12.4 z srm cc sw use slider to adjust tilt key goal: identify imposters z srm avoid warnings based on imposter signatures note: presence of an imposter may not preclude warning issuance common feature #1: blocky velocity srm no clear v gradient common feature #2: unrealistic shear srm unnaturally long, azimuthal shear common feature #3: wrong location z srm cc sw may see real couplet near arrow location with some storms common feature #4: unbalanced vrot srm 28-30 kts 60-85 kts regularly inspect storm motion to ensure accuracy common feature #5: at lower levels z srm cc sw ~4kft agl common feature #6: weaker returns z srm cc sw < 20-25 dbz <0.9 other potential features #1 z srm cc sw noisy v/srm high sw mix of main side lobe returns of similar strength other potential features #2 z srm cc sw smooth v/srm low sw side lobe return likely dominates main lobe real couplet imposter identification process boettcher and bentley (2022) step #1: circulation location bentley et al. (2021) returns in white oval suggest couplet is an imposter step #2: velocity texture z srm z srm imposters look like velocities marked by red x step #3: vertical examination 0.5 0.9 1.4 1.9 2.4 3.2 4.0 5.1 6.4 use slider to adjust tilt summary identified two velocity contamination sources: tbss vertical sidelobe contamination showed 6 common traits of imposter circulations showed 2 alternate traits & why they might appear that way presented a 3-step process for identifying imposter circulations: location velocity texture vertical examination incorrect you did not select the correct response. continue continue continue continue continue continue correct that's right! you selected the correct response. continue continue continue continue continue continue question #1 of 4 which of the following is a common source of velocity contamination with supercells elevation sidelobes elevation sidelobes elevation sidelobes elevation sidelobes elevation sidelobes elevation sidelobes dual-polarization streaks dual-polarization streaks dual-polarization streaks dual-polarization streaks dual-polarization streaks dual-polarization streaks hook echoes hook echoes hook echoes hook echoes hook echoes hook echoes poor storm motion usage poor storm motion usage poor storm motion usage poor storm motion usage poor storm motion usage poor storm motion usage incorrect you did not select the correct response. continue continue continue continue continue continue correct that's right! you selected the correct response. continue continue continue continue continue continue question #2 of 4 which of the following features are commonly seen signatures with velocity couplet artifacts? (choose all that apply) velocity data appear blocky velocity data appear blocky velocity data appear blocky velocity data appear blocky velocity data appear blocky velocity data appear blocky azimuthal shear unrealistically long and/or strong azimuthal shear unrealistically long and/or strong azimuthal shear unrealistically long and/or strong azimuthal shear unrealistically long and/or strong azimuthal shear unrealistically long and/or strong azimuthal shear unrealistically long and/or strong velocity couplet located along storm’s front flank velocity couplet located along storm’s front flank velocity couplet located along storm’s front flank velocity couplet located along storm’s front flank velocity couplet located along storm’s front flank velocity couplet located along storm’s front flank velocity maxima in srm have markedly different magnitudes velocity maxima in srm have markedly different magnitudes velocity maxima in srm have markedly different magnitudes velocity maxima in srm have markedly different magnitudes velocity maxima in srm have markedly different magnitudes velocity maxima in srm have markedly different magnitudes artifact seen in lowest portions of the storm artifact seen in lowest portions of the storm artifact seen in lowest portions of the storm artifact seen in lowest portions of the storm artifact seen in lowest portions of the storm artifact seen in lowest portions of the storm artifact located in weaker reflectivity returns artifact located in weaker reflectivity returns artifact located in weaker reflectivity returns artifact located in weaker reflectivity returns artifact located in weaker reflectivity returns artifact located in weaker reflectivity returns incorrect you did not select the correct response. continue continue continue continue continue continue correct that's right! you selected the correct response. continue continue continue continue continue continue true true true true true true false false false false false false question #3 of 4 true or false. an imposter circulation couplet may appear to have very smooth velocity data with low spectrum width values when the return signal is dominated by power from the sidelobe in a particular part of the storm. incorrect you did not select the correct response. continue continue continue continue continue continue correct that's right! you selected the correct response. continue continue continue continue continue continue question #4 of 4 please choose each recommended step for identifying an imposter circulation. (select all that apply) determine if apparent circulation in the correct place determine if apparent circulation in the correct place determine if apparent circulation in the correct place determine if apparent circulation in the correct place determine if apparent circulation in the correct place determine if apparent circulation in the correct place look at texture of velocity data and determine if it’s realistic look at texture of velocity data and determine if it’s realistic look at texture of velocity data and determine if it’s realistic look at texture of velocity data and determine if it’s realistic look at texture of velocity data and determine if it’s realistic look at texture of velocity data and determine if it’s realistic examine vertical structure of storm for possible source of velocity contamination examine vertical structure of storm for possible source of velocity contamination examine vertical structure of storm for possible source of velocity contamination examine vertical structure of storm for possible source of velocity contamination examine vertical structure of storm for possible source of velocity contamination examine vertical structure of storm for possible source of velocity contamination analyze correlation coefficient data to make sure returns are meteorological analyze correlation coefficient data to make sure returns are meteorological analyze correlation coefficient data to make sure returns are meteorological analyze correlation coefficient data to make sure returns are meteorological analyze correlation coefficient data to make sure returns are meteorological analyze correlation coefficient data to make sure returns are meteorological peruse spectrum width data and make sure values are low peruse spectrum width data and make sure values are low peruse spectrum width data and make sure values are low peruse spectrum width data and make sure values are low peruse spectrum width data and make sure values are low peruse spectrum width data and make sure values are low rac principles roadmap <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Welc"> <Style FontFamily="+minor" FontSize="11" /> </Span> <Span Text="ome to this lesson on Velocity Contamination Artifacts. "> <Style FontFamily="+minor" FontSize="11" ForegroundColor="#464646" LinkColor="#464646" /> </Span> <Span Text="This lesson is part of the Principles of Meteorological Doppler Radar topic in the Radar &amp; Applications Course. Let’s get started."> <Style FontFamily="Arial" FontSize="11" FontIsBold="False" FontIsItalic="False" FontIsUnderline="False" FontIsStrikeout="False" ForegroundColor="#464646" Elevation="Normal" DisplayCase="AsIs" LinkColor="#464646" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style LeadingMargin="0" FirstLineMargin="0" Justification="Left" ListLevel="1" LineSpacingRule="Multiple" LineSpacing="20" SpacingBefore="4.32" SpacingAfter="0"> <ListStyle ListType="None" ListTypeFormat="Plain" Start="0" Color="#000000,00" BulletChar="•" BulletFont="Arial"> <BulletPicture Size="0x0" /> </ListStyle> </Style> <Span Text=" Here is a roadmap for the RAC Principles topic. This lesson, which is part of the Base Data Quality Management section, is highlighted. Once you have had a chance to look over the roadmap, advance to the next slide."> <Style FontFamily="+minor" FontSize="11" FontIsBold="False" FontIsItalic="False" FontIsUnderline="False" FontIsStrikeout="False" ForegroundColor="#464646" Elevation="Normal" DisplayCase="AsIs" LinkColor="#464646" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Here are the learning objectives for this lesson. Please take a moment to read through them and advance to the next slide when you are ready."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" RAC has a lesson dedicated to data quality issues, and velocity contamination sounds like a data quality issue. So, why does Velocity Contamination have it’s own lesson? Well, this topic has grown in visibility over the last several years. Since this issue disproportionately impacts Tornado Warning decisions, we see it as a higher profile problem. Researchers recently focused attention on the subject in three papers as well. Nai et al. (2020) coined the term elevation sidelobe contamination to describe what we have commonly called vertical sidelobe contamination. They identified some parameters that best show when this contamination occurs, which was more fully defined in Boettcher and Bentley (2022). This lesson will borrow from their work to provide a basic methodology for identifying when velocity contamination occurs due to either elevation sidelobe contamination or three-body scatter spikes. In Bentley et al. (2021), they found about one in four low-level velocity couplets over a three year period were potentially impacted by this artifact. Armed with this information, hopefully you see it as a higher profile problem that matters, too."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Elevation sidelobe contamination is the more common source of velocity contamination of the two we mention in this lesson. We show an example mentioned by Boettcher and Bentley (2022) of elevation sidelobe contamination on the 0.5 tilt indicated by the white triangle in each product. We show a 0.5 SAILS tilt collected between the 3.2 and 4.0 scans, and you can use the slider bar on the bottom of the slide to view each tilt. Forecasters commonly make a mistake when diagnosing elevated sidelobes by only focusing on the tilts a specific range of tilts away from 0.5 (usually about 3 degrees) and directly above the affected area. That’s one reason we will refer to the phenonmena as elevated or elevation, and not vertical, sidelobes in this lesson. In this particular example, we likely see a more cumulative sidelobe contamination not only from directly above on the 6-10 degree tilts, but also from the strong reflectivity returns just to the west (and at the same range) of the highlighted area on all of the tilts between 0.5 and 10 degrees (as indicated by the white arrows)."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Three body scatter spike (or TBSS) contamination occurs when you observe a TBSS in the vicinity of a storm’s inflow region. In most cases, these situations occur when storms are located south of the radar and the storm has a significant hail core. Boettcher and Bentley (2022) presented this example, and it has multiple interesting features. A prominent TBSS eminates from the back side of the storm in the supercell’s inflow region forward flank. The reflectivity values in this region approach 30 dBZ, but the storm-relative velocity, correlation coefficient, and spectrum width all show clear contamination. Additionally, this case shows signs of both TBSS and elevation sidelobe contamination. Notice how the SRM and SW data appear different in the western and eastern sides of the prominent spike in Reflectivity? In the area where SW is higher to the west (highlighted by the solid white line), we likely see both forms of contamination. Evidence of the TBSS remains prominent through the 6.4 tilt. The area highlighted by the dashed line likely has less TBSS influence and appears dominated more by the elevation sidelobe contamination from the core visible aloft from 3.1 to 8.0 degrees. Even though this elevated core isn’t directly over the TBSS, it still falls in the sidelobes contributing to the returned signal."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Now that you have seen some examples, you should have a better understanding about what we mean about velocity contamination. We highlight this issue in order to achieve an important goal: Identifying velocity contamination that may result in imposter velocity couplets. Identifying imposter circulations has critical importance to reducing Tornado Warning issuance on storms that would otherwise not warrant it. From here on out, this lesson focuses on identifying velocity artifacts due to elevation sidelobes as those situations are more challenging (and occur more frequently) than TBSS contamination. Before we discuss specifics on how to identify these imposters in the remainder of this lesson, I need to point out an important point. Just because a storm contains an imposter circulation, that shouldn’t prevent you from issuing a warning if the remaining evidence indicates a tornado is likely present or imminent. You still need to follow the preponderance of the evidence and make the best scientifically defensible decision you can."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" For the first few features, we will focus on the velocity data. In this example, we see an apparent velocity couplet in SRM. However, a quick look suggests a problem at the inbound velocities on the right side of couplet. See how the velocities look blocky with no distinguishable velocity gradient or maximum near the center of the circulation. Typically, velocity data in a mesocyclone appears as a Rankine vortex. We will discuss what that is in more detail later in RAC, but a Rankine vortex doesn’t look like this."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Another questionable aspect of this potential circulation is the unrealistic region of azimuthal shear. The shear region in this box extends to approximately 3 nautical miles in length. Legitimate mesocyclonic shear rarely gets that large. That fact combined with the blocky velocity mentioned previously makes this circulation appear more suspicious."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Another quirk with this possible circulation is it’s location. The circle marks the approximately the center of the apparent circulation in the velocity data. This location puts the circulation more along the storms forward flank than near the hook like appendage in Reflectivity indicated by the arrow further to the south. While this may seem a subtle difference, it’s an important one. In some storms with a potential imposter like this one, you will notice a second circulation in the area where you would expect it. Being able to spot the difference helps you gauge the true rotational velocity for the storm and not get sucked in by the imposter."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Let’s go back to the SRM data for the next feature common with imposter circulations. Assuming you have a good storm motion, most low-level mesocyclones in SRM will have relatively balanced velocity couplet maxima. I’m not saying they will be the same, but the difference might be 15-20 kts. In this circulation, the maxima are more like 40-50 kts different. This feature depends on the radar operator using a good storm motion, so regularly inspect your SRM storm motion when investigating this one."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" Velocity couplet imposters tend to be seen in the lower parts of the storm in the weak echo region underneath the midlevel reflectivity overhang. For classic supercells, you will usually see them in the lowest 6 km AGL of a storm. For mini-supercells, that height would be even lower. In other, more intense, deeper storms, you might see velocity contamination even higher in the storm. In other words, typical heights don’t mean a hard and fast rule."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" "> <Style FontFamily="+minor" /> </Span> <Span Text="The last common feature is that the contaminated velocity values tend to be found in areas with weaker reflectivity returns. Expect most Reflectivity values to be 20-25 dBZ or less with corresponding CC values below 0.9 (suggesting non-meteorological echoes). In this particular example, the CC values are a little higher than what you may typically see in comparable situations. In this case, the elevation sidelobe returns likely dominate the signal in parts of the highlighted area, resulting in CC values more comparable to Mie scattering from larger hail than from typical non-meteorological returns."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" You may see some other potential features with velocity contamination depending on how the main and side lobes contribute to the returned signal. In one scenario, you might see noisy velocity data associated with high Spectrum Width values. When this happens, the returned power likely contains a fairly even mix of power return from the main and side lobes. The same scenario might occur if the sidelobes sample different parts of the storm with significantly different velocity values (or if you get a mix of TBSS and sidelobe velocity contamination)."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" You could also observe fairly smooth velocity data associated with low Spectrum Width values in an imposter circulation like the inbound velocities highlighted here. These situations occur when the side lobe return likely dominates the signal from the main lobe and the sampled velocity is fairly uniform. Before I move on, I need to point out one more thing in this particular example. While the area I highlighted shows a clear imposter, another area to the southwest appears to be part of a legitimate couplet. Even though a clear imposter circulation exists, this storm still warrants a Tornado Warning due to the remaining features visible in this storm."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" At this point, we have explained many details on velocity contamination. Before we wrap things up, I want to walk through the methodology that Boettcher and Bentley (2022) proposed in their study and shown on this slide. When forecasters interrogate a storm with a circulation that might be an imposter, they should focus on three steps to confirm that the circulation likely is an imposter."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" First, look at the potential circulation’s location to identify if it is an imposter. Specifically, is the circulation located near the RFD and/or hook echo like the black circle in the image? Or is it located more in the forward flank and with a significant amount in weak echo returns like the area in the white oval in the image? The latter location would suggest the circulation is an imposter."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" The second step involves looking at the velocity texture in the potential imposter. Real circulations (like the example marked by the green check mark) generally have a Rankine vortex appearance with a smooth increase in velocities to well-defined velocity maxima. Imposter circulations (like the one marked by the red X) have a blockier appearance, with no clear gradient in velocities visible."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" In the last step, you want to look at the vertical structure of the storm to identify highly reflective targets that could be struck by sidelobes. Remember that those sidelobe targets need to be located at the same range as the main lobe, so it’s more of an arc than a true line normal to the beam. Ideally, you would use a vertical cross-section oriented perpendicular to the radar beam to perform this task. However, radar cross-section tools in NWS operations have some significant limitations at the moment. As a result, the better option is to analyze the radar data in an all-tilts display to look for strongly reflective cores. I have added some annotations on the slide to help on the pertinent tilts. It’s the blue, inbound radial velocities on the 0.5 tilt that appear to be corrupted. Looking aloft, you can see several tilts have strong reflectivity values perpendicular to the beam just to the west of the impacted area."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style /> <Span Text=" In summary, we discussed various aspects of the causes of and ways to identify velocity contamination artifacts. The two most significant causes of these artifacts were three-body scatter spikes and elevation sidelobe contamination. When these artifacts result in a potential imposter circulation, we discussed 6 common traits they might have. These traits include blocky velocities, unrealistic shear, wrong location, unbalanced velocity maxima, seen at lower levels, and in weak returns. In some cases, velocity data may be noisy with high spectrum width values if the mainlobe and sidelobe returns are similar. In other cases, the velocity data may be smooth with lower spectrum width values if the sidelobe contamination dominates the signal. Forecasters can follow a simple three step process to identify potential imposter circulations. First, make sure the circulation is located in the correct location. Second, examine the velocity texture to make sure it appears realistic. Third, examine the vertical storm structure to see if there’s highly reflective sidelobe returns near and above the low-level storm inflow.&#xA;"> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> <Block> <Style /> <Span Text=" When you are ready, please proceed to the next slide to start the quiz."> <Style FontFamily="+minor" FontSize="11" /> </Span> </Block> </Content> </Document> <Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Content> <Block> <Style LeadingMargin="0" FirstLineMargin="0" Justification="Left" ListLevel="1" LineSpacingRule="Multiple" LineSpacing="20" SpacingBefore="4.32" SpacingAfter="0"> <ListStyle ListType="None" ListTypeFormat="Plain" Start="0" Color="#000000,00" BulletChar="•" BulletFont="Arial"> <BulletPicture Size="0x0" /> </ListStyle> </Style> <Span Text=" "> <Style FontFamily="+minor" FontSize="11" FontIsBold="False" FontIsItalic="False" FontIsUnderline="False" FontIsStrikeout="False" ForegroundColor="dk1,00" Elevation="Normal" DisplayCase="AsIs" LinkColor="dk1,00" /> </Span> <Span Text="You have successfully completed this course. You are now ready to advance to the next lesson in this topic. Choose the Exit button to close the window and record your completion."> <Style FontSize="11" /> </Span> </Block> </Content> </Document>