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Upper Level Synoptic Influences

on Cloud Top Heights

over Monterey Bay

18-23 July 2005

LCDR Beth Sanabia

OC3570

19 September 2005

Table of Contents:

Introduction……………………………………………..1

Determining Cloud Top Heights………………………..2

Sonde Launch Timeline and Cloud Top Heights……….4

Synoptic Weather Pattern……………………………….5

Fort Ord Profiler………………………………………...7

Case One…...……………………………………………9

Case Two.………………………………………………11

Case Three………………………………………………15

Refractive Conditions and Naval Applications…………16

Conclusion and Lessons Learned……………………….17

Appendix 1: Technical Information and Specifications..19

Appendix 2: Synoptic Charts…………………………..20

List of Tables:

Number / Title Page

1. Sonde launch times and associated cloud top heights (measured in meters)…………………..4

List of Figures:

Number / Title Page

1. Cloud top heights compared to radiosonde launch times during OC3570

cruise on R/V Pt Sur………………………………………………………………………..…5

2. from Lentz: Spring Transition over the Northern California Shelf (Fig 2)

(from OC3570 lecture)…………………………………………………………………………5

3. Fort Ord profiler data from 18-21 July 2005………………………………………………….8

4. Case One: Temperature and dew point profiles from radiosonde soundings three and four….9

5. Case One: 300mb and 500mb GFS analyses over GOES West satellite imagery…………... 9

6. Case One: M-profiles from radiosonde soundings three and four…………………………...10

7. Case Two: Temperature and dew point profiles from radiosonde soundings fourteen and

fifteen………………………………………………………………………………………....11

8. Case Two: 300mb and 500mb GFS analyses over GOES West satellite imagery……...…..12

9. Case Two: 300mb from the 00z GFS model run on 18 July 2005……………………...…..13

10. Case Two: M-profiles from radiosonde soundings fourteen and fifteen……………………14

11. Case Three: Temperature and dew point profiles from radiosonde soundings twenty and

twenty-one…………………………………………………………………………………...15

12. Case Three: 300mb and 500mb GFS analyses over GOES West satellite imagery………..16

13: Case Three: M-profiles from radiosonde soundings twenty and twenty-one……………….16

Introduction:

When I moved to Monterey just over a year ago, I did not understand quite why everyone thought this place was so great. It was foggy every morning, I had to bring a jacket or a sweater wherever I went and the ocean was freezing (at least to my East coast point of view). One year later, I now share the view that Monterey is a great place, however, I think it is more because of the people than the weather. Those sentiments were reinforced completely this past July when the fog came and just seemed to stay.

Every other place that I have been stationed as a METOC officer, I have had to dedicate a fair portion of my time to understanding the weather at that location, or in the case of my ships, not just where we were, but where we were going as well. That comes with the job and is really a fairly fun thing to do, but I will have to admit when I got here and my first priority was not getting straight the weather regimes in Monterey, I did not exactly exhibit some motivation and do it myself.

One nice thing about being a student is that my professional responsibilities are limited to academic endeavors, and so to this point understanding the weather in Monterey has been more a matter of personal curiosity than professional requirement. As a result, over the past year I have spent loads of time studying calculus, thermodynamics and ocean dynamics and minimal time examining Monterey weather. That situation changed for the better as a result of this course (OC3570), in which I was grateful to have the opportunity to earn credit for investigating the synoptic patterns that influence the gloomy weather that seems to dominate a fair portion of each summer in Monterey.

Accurately forecasting fog and dust has been a continuous challenge to me, particularly with regard to their thickness and duration. As with other forecasters, I worked using satellite shots and models to predict these events; however, there was usually precious little time on the back end of an event for a detailed analysis of what actually transpired – usually it was a quick recheck of the models and a mental note of what occurred and a note in the trip log of what was missed, how and a recommendation for how to handle it in the future. It was for this reason that I elected to go backwards for this study – to take what actually happened over Monterey Bay between 18 and 23 July 2005, and then look back at the satellite shots and model runs to see why it occurred. In an attempt to better understand the thickness of the stratus layer that pervades the Monterey coast, I chose to examine the variation in cloud top heights and determine what upper level (300 and 500mb) synoptic weather patterns impacted that variation.

Determining Cloud Top Heights:

Within the guise of approaching the problem in reverse, my first step was to determine the actual cloud top heights. As they are not observable from the surface, I used data from our radiosonde launches to determine the ground truth. On the temperature and dew point profiles from the radiosonde launches, the top of the cloud is marked by a sharp separation of the temperature and dew point (increase in temperature and decrease in dew point), and this served as my mark for cloud top height.

There were several potential issues with this choice. The first was that nearly all of the sondes were “up-downs” in which the sonde not only measured temperature, relative humidity and pressure on ascent, it measured them on a controlled descent as well. To accomplish this, a plastic syringe was inserted in and affixed to the base of the balloon and at the time of the launch, the plunger was removed allowing helium to escape at a slow enough rate that the balloon could still climb to a significant altitude, (up to 500mb or 18,000 feet in some cases), but would begin to lose buoyancy and therefore begin to sink before the balloon popped. As a result, the sonde would then descend slowly toward the earth and continue to collect data on that descent. The challenge this method presented was that the soundings measured two different columns of air at two different points in time. Fortunately, the soundings we measured proved to be quite similar in the region of the boundary layer. The primary area that differed between the up and down profiles was the altitude where the temperature and dew point split, which was important because it marked the top of the cloud. Typically, the ascending profile showed the split occurring at an altitude higher than the one shown by the descending profile. When this occurred I gave preference to the “down” measurement, as when passing through a cloud, condensation can form and accumulate on the relative humidity sensor. When this occurs on ascent the sonde continues to give a false indication of increased humidity past the top of the cloud. It does dry as the sonde continues upwards, but that residual moisture contaminates the reading for humidity beyond the cloud top. On descent, the sensor is dry prior to encountering the top of the cloud, so it provides a more accurate reading and is therefore the better choice to mark the altitude of the cloud top.

The next potential issue had to do with accuracy in the horizontal, as the radiosonde does not rise directly over the point at which it is launched, rather it can travel up to several miles horizontally during its ascent, and in this case, its descent as well. A second problem with horizontal resolution had to do with the ship’s movement. The ship was transiting during many of the launches, so any meteorological conditions observed at the ship would not directly correspond to the position of the balloon after the balloon was launched. I resolved these issues by establishing my threshold for the variance in cloud top height at 100 meters or more. Although cloud top heights can vary significantly over very short distances, I reasoned that since this was a layer of stratus clouds, the overriding subsidence should cause fairly uniform tops. Upon examining the results, there were only three instances during the week where the tops changed by more than 100 meters, so I elected to keep 100 meters as my threshold. Additionally, since I was looking at the upper levels of very large-scale weather patterns, any effects should be observed on a similar scale on the earth’s surface. Small variations that resulted from a few nautical miles difference in location, would not, in my estimation, have been caused by synoptic scale features. So, in short, I was looking for large changes in cloud top heights, and the large upper level weather patterns that might have caused them to occur.

Sonde Launch Timeline and Cloud Top Heights

Date |Sonde Number |Time (Local) |Cloud Top Height (m) |  |Date |Sonde Number |Time (Local) |Cloud Top Height (m) | |18-Jul-05 |1 |10:28:21 |300 |  |21-Jul-05 |12 |11:15:10 |490 | | |2 |11:15:35 |350 |  | |13 |15:49:13 |500 | | |3 |13:45:45 |310 |  | |14 |17:01:38 |490 | |19-Jul-05 |4 |3:19:59 |450 |  | |15 |22:01:23 |600 | | |5 |5:14:39 |430 |  |22-Jul-05 |16 |4:13:31 |600 | | |6 |10:19:30 |430 |  | |17 |6:51:18 |550 | | |7 |15:23:03 |400 |  | |18 |12:11:41 |460 | | |8 |19:36:57 |370 |  | |19 |15:21:05 |500 | | |9 |22:29:20 |385 |  | |20 |17:57:14 |500 | |20-Jul-05 |10 |3:20:23 |400 |  | |21 |23:44:55 |50 | | |11 |8:09:00 |450 |  |23-Jul-05 |22 |4:07:23 |50 | |  |  |  |  |  | |23 |8:05:04 |0 | |  |  |  |  |  | |24 |11:22:04 |0 | |

Over the six days of the cruise we launched many radiosondes. Twenty-four of those had legible profiles, and gave the results for cloud top height listed in Table 1. I found that an easier way to visualize the cloud tops was to transform the tabular data above into the chart shown in Figure 1, with representative heights shown above the sonde launch times. The numbers circled in each figure annotate the three instances when the cloud top heights changed by 100 meters or more. On the graphic depiction, I carried the status quo (cloud heights at 400 meters) through the period while we were in port. With the three cases identified, the next step was to examine the synoptic picture.

Synoptic Weather Pattern:

Climatologically speaking, the Eastern Pacific (EASTPAC) high pressure system is known as a “semi-permanent” feature because it is nearly always present in the Eastern Pacific Ocean. The position of the high does vary with the seasons, and its usual summer location is shown in Figure 2. Over cruise, the location of the high was in general agreement with the pattern shown in Figure 2. The importance of this feature was both relevant and significant to this study as the high pressure drives subsidence that caps the inversion, often resulting in a layer of stratus clouds that blankets the California coast.

Recognizing that Figure 2 depicted the weather pattern at the surface and that the scope of my study involved upper level (300mb and 500mb) patterns, my next step was to examine these levels and determine what transpired at each level during the cruise. I chose two methods to examine each of these levels, the first was the GFS (Global Forecast System) model run that I had downloaded from FNMOC’s (Fleet Numerical Meteorology and Oceanography Center’s) website the night prior to my departure with the first group. GFS is a global model produced by the National Centers for Environmental Prediction, and more detailed characteristics of this model are included in the “Technical Information and Specifications” section of this paper (Appendix (1)). I chose to use the model primarily because I have used it frequently in the past. The colored streamlines of the polar front jet on the 300mb and the positive and negative vorticity shown on the 500mb are critical aspects of my forecast preparation. In this case I used the model to baseline what I should expect to see and used my second resource, the GFS analysis overlaid with observation data on a GOES West satellite shot (also discussed in the Technical Information and Specifications section), to see what actually happened. Coupling these two products proved to be an effective way to determine the upper level synoptic pattern.

The 300mb charts depict heights of columns of air at that pressure level. An average height for 300mb is approximately 30,000 feet; however, heights can vary significantly. It is the differences between these heights that cause the high winds known (at that level) as the jet stream, which drives the flow of storm systems around the globe. In this instance, the flow of the 300mb chart was zonal and became meridional later in the period. The Polar Front Jet (PFJ) was zonal, then weakened, then reestablished in the base of the long wave trough in the central Pacific. The most relevant feature at this level was the cut off low height center that remained at 135 degrees West longitude and deepened until 12z on 21 July, when it moved northeast into the flow. Appendix (2) of this paper contains the full model runs and satellite shots for both the 300mb and 500mb levels throughout the cruise period.

The 500mb charts also depict heights of columns of air at that pressure level. The average height for this level is approximately 18,000 feet. This is a good height to see “short wave” troughs and ridges – smaller scale troughs and ridges which propagate along the long wave pattern established by the winds at 300mb. Still on the synoptic scale, these are one of the smaller features I was looking for during the period. Another small feature I was looking for was vorticity, a measure of the upward spin (or curl) of a column of air, which is also depicted on the 500mb chart. During this period, short waves and vorticity both played major roles in the weather over Monterey. Overall, the axis of the long wave trough remained along the western Canadian border until 21 July at 12z when it reoriented to the southwest. The relevant feature at this level was the same cutoff low height center at 135 West longitude, which, supported by Positive Vorticity Advection (PVA), deepened and then moved northeast. The vorticity maximum associated with this low height center crossed the Oregon coast at 12z on 22 July.

Fort Ord Profiler

With an understanding of both changes in cloud top height and the synoptic weather patterns, I decided to consult a third source – the Fort Ord profiler – as a second “ground truth”. Located several miles from our radiosonde launches, the profiler offered a way by which to verify that changes in the cloud tops observed with the radiosondes were bay-wide changes,

rather than coincidental changes, just caused by change in our location. This proved to be a wise decision as the primary benefit of the profiler turned out to be the continuous nature of its

sounding. Observing the rise and fall of the layer over time over Fort Ord helped fill in the gaps between the radiosonde profiles, even though the sounder was not directly over Monterey Bay.

The profiler displays a vertical depiction of winds and virtual temperature, increasing in time from right to left. The shaded regions represent virtual temperature, and the cloud top is generally located at the just above the lightest green and below the yellow. The three numbered regions enclosed by black rectangles denote the three cases when the radiosonde profiles indicated an increase or decrease of cloud top height of 100 meters or more. Overall, the profiler

indicates a continuous layer of stratus with tops between 300 and 400 meters from 18 to 20 July. The top dropped slightly early on the 21st, built to 600-700 meters early on the 22nd and dissipated completely that afternoon. The 23rd showed the emergence of a low stratus deck, which again broke in the afternoon. This series roughly matched the pattern observed with the radiosondes and depicted in Figure 1, differing in the initial rise (case one), but matching closely during the rise and fall of the tops on the 22nd and 23rd (cases two and three).

Case 1:

The first instance of a sharp increase occurred between sonde launch numbers 3 and 4, with an increase in cloud top height of 140 meters over an eleven-hour period. The two relevant profiles are shown in Figure 4.

Synoptically during this time, there was not any major activity. The 300mb chart shows zonal flow over the northern Pacific and western United States and the closed low height center

remaining stable at 135 West. The only potential cause I can determine at this level is the relaxation of the high height center over southern California between 00z and 12z on 19 July. Closer examination, however, reveals that heights actually rose slightly, from 976.5 meters to 978.6 meters over the twelve hours between 12z, 18 July and 00z, 19 July, and then dropped slightly to 974.7 meters. While theoretically the decrease in subsidence that results from the weakening of a high can have the effect of lifting the cloud top height, a shift in central height value of only a few meters at 300mb is not significant enough to cause the 140 meter increase in cloud top height observed during case one.

Examining the 500mb chart confirms this assessment. Heights rise on the chart from 594.2 meters to 596.9 and then drop to 594.6. While this parallels the change in heights at 300mb, even a diurnal flux could cause this small change. Hence, the fluctuation in cloud top height did not result from these changes in the high over southern California.

The M-files for the respective soundings also yield no significant findings. There is little variation in refractive conditions, as shown in Figure 6, giving no clear indication of changes in stratification over the launch sites.

Perhaps the second “ground truth” location might provide some insight. We observed previously that the Fort Ord profiler did not share the same rise in cloud tops observed by radiosonde number four. By observing the 18-20 July series in Figure 3, however, what is obvious is the slight, but consistent, diurnal variation in cloud top height.

It is my assessment that the increase in cloud top heights observed between launches three and four was due at least in part to diurnal heating and cooling. Sonde three was launched in the afternoon, and as the sun went down the atmosphere cooled (the dew point profile remained roughly constant in the boundary layer, but the temperature cooled, closing the gap between the two traces.) The cooler air can hold less moisture and so the area just above where the cloud top was during the day now becomes saturated, effectively lifting the cloud top height. There may be additional causes for the 100-plus meter variation at the mesoscale or microscale, but the upper level synoptic patterns do not cause the change in cloud height in case one.

Case Two:

Case two, on the other hand, has an obvious synoptic cause. Figure 7 shows the cloud top increased in height by 110 meters, slightly less than the 140 meters in case one; however, this increase occurred over a much shorter period – only five hours.

Synoptically, the 300mb chart shows the long wave trough axis reorienting to the southwest and the cutoff low being reabsorbed into the flow as a major short wave trough. The 500mb shows this same orientation of the long wave trough and depicts the progression of the short wave northeastward and centered directly over the Oregon coast at 12z on 22 July. Although three time series are included in Figure 8 for reference, case two begins at the 2nd column and ends halfway between the 2nd and 3rd columns. The first column is included for reference.

Figure 8: Case Two: 300mb and 500mb GFS analyses over GOES West satellite imagery.

As the short wave approaches the coast, it brings with it upward vertical motion typical of troughs, and that upward vertical motion weakens the subsidence of the EASTPAC high, and therefore weakens the inversion. This increases the vertical extent of the cloud tops, but does not carry with it enough strength to break the inversion (which happens in case three). The positive vorticity advection, which is an indicator of this upward vertical motion, is particularly evident in the GFS model run from 00z on 18 July, (reference the orange bull’s-eye on the California-Oregon border). Figure 8 shows the progression of the vorticity associated with the upper level trough as it moves from the eastern Pacific northeast to the Oregon coast. Since these two

Figure 9: Case Two: 300mb from the 00z GFS model run on 18 July 2005.

graphics came from the model run 84 and 96 hours prior to the times shown in the boxes at the bottom of each frame, several things are evident. First, the position of the short wave trough is about nearly twelve hours ahead of what actually occurred, as evident in comparison to Figure 8. Second, while the timing of the movement is off, the path of the short wave is very close to what actually transpired. The key feature here, however, is the vorticity as noted previously, which is annotated in this model and present, although not annotated, in Figure 8.

This increase in cloud top height is also seen at Fort Ord, where the profiler captured the increase in Figure 3. Interestingly, the increase captured in the case two timeframe appears to be only a small portion of the overall increase that began in the late hours (GMT) of the 21st. This raises the question, did the increase occur in both places at the same time? If so, earlier sondes launched during the late GMT hours of the 21st should reveal similar conditions at sea. Or, did the event occur on land first and then over water afterward, and if so, why? Two other radiosondes were launched between 18z on the 21st and 00z on the 22nd. Sonde number 12 was launched at 1815z and indicated a cloud top height of 490 meters. Sonde 13 was launched at 2249z and indicated a cloud top height of 500 meters. (Sondes 14 and 15 showed the large increase, when the tops went from 490 meters to 600 meters.) This result indicates that the increase in cloud top height that occurred over Fort Ord late in the day (GMT) on the 21st did not occur over the bay at the same time. My professor discovered the reason behind this, as it was she who suggested that daytime heating at Fort Ord and the resulting sea breeze might have instigated the increase in heights over land before they occurred over water. I concur with her assessment.

Examining the M-profiles for sondes 14 and 15 in Figure 10 reveals a change in the structure of the elevated duct. The lower duct (between 400-600m) elevates (to 500-700 meters) and solidifies in form (strengthens). The upper elevated duct (between 800-1000m) in the initial profile dissipates completely.

The naval application of ducting in general revolves around the fact that ducts facilitate electromagnetic (and therefore radar) propagation. Platforms that can place sensors in a duct or just above it (therefore enabling the radar wave to refract into the duct) typically achieve extended ranges for those sensors. Optimizing tactical advantage from this environmental condition requires knowing not only how the sensor will propagate within the duct, but predicting how the characteristics of the duct will change over time. While Figure 10 indicates a change in the elevated duct, the synoptic picture indicates that this M-profile is as transitory as the short wave trough. As a result, it would not be wise, operationally speaking, to brief any ranges based off this profile, since the atmosphere is changing fairly rapidly. Instead it would be prudent to wait another 6-12 hours until ducting conditions stabilized. If missions happened to fall within this window, it would be feasible to run the ranges in AREPS (Advanced Refractive Effects Prediction System) and brief them and note their varying nature instead of briefing a “range of the day”.

Case Three:

The third and final case in which cloud top heights changed by 100 meters or more occurred just after case two, when the tops decreased from 500 meters to 50 meters in the early morning hours of 23 July (GMT). The relevant soundings are shown in Figure 11.

Synoptically, case three is a continuation of case two. The trough axis transited northeastward and Figure 12 shows that flow stabilized across the coast at both the 300 and 500 mb levels. The upward vertical motion resulting from the passage of the trough is enough to break the inversion and drop the cloud top height to 50 meters, as indicated in sonde 21’s profile, and eliminate the cloud deck completely shortly thereafter. The Fort Ord profiler also captures this dramatic drop in cloud top height, as shown in box 3 of Figure 3.

The M-profiles associated with case three are shown in Figure 13. The nearly 600-meter elevated duct just off the surface weakens and becomes an elevated duct of half the height between 300 and 600 meters in altitude. Just as before, refractive conditions are changing at such a rapid pace through the early part of this case that it would not be prudent operationally to calculate and brief predicted ranges based on the first of these profiles. Conditions do stabilize following this case, though, so the temporal accuracy of the ranges based on the second sounding would be much greater than those based off the first.

Refractive Conditions and Naval Applications

Forecasting refractive conditions is a challenge in and of itself, and lends itself to a project of this magnitude or an even greater one. For purposes of my project, an assessment of the potential impact of the changes in height on radar propagation is sufficient, and in each of the latter two cases the impact was degraded temporal accuracy of predicted sensor ranges due to changing atmospheric conditions. The fact that the atmosphere was changing rapidly outweighed the potential tactical advantages that could have been derived from exploiting the ducts for enhanced electromagnetic propagation. By the time the commander can get assets in place in a situation like this, the environment has changed, must be sensed and characterized once again, and the assets shifted accordingly. “Chasing the environment” in this method is neither practical nor advised. Once again, the prudent move is to brief the changing conditions, rather than specific ranges.

Conclusion and Lessons Learned

I learned much more than I anticipated by working on this project. First, there is not a synoptic cause for every instance of significant increase or decrease in cloud top heights. Second, I used to always associate high pressure with good weather and low pressure with bad weather. This project showed that the reverse could be true. Here it was the subsidence from the EASTPAC high that caused the stratus clouds that dominated the month of July, and it was an upper level trough that came through and cleared the skies. The situation makes sense intuitively, as the upward vertical motion from the low disrupts the subsidence enough to weaken the inversion and can be strong enough to thoroughly mix the layer and dissipate the cloud deck completely.

I also learned several lessons about conducting an analytical project of this magnitude. First, there was so much information that I was surprised at the time required just to sift through available products and determine what information to use. This was in stark contrast to my previous experience with the significantly smaller number of products available through the limited bandwidth at sea. Second, I intentionally chose to work at the synoptic level, as I did not want to nitpick the 1-10 meter changes in cloud top heights. However, in doing so, I think my assessments of cloud top heights could have been more accurate with dedicated time devoted to the data itself, rather than just the profile. I do not think it mattered in this case, as I think I correctly determined the synoptic causes of the increase and decrease. In the future though, that may matter significantly, so I will remember it for future projects.

Appendix 1: Technical Information and Specifications:

Radiosonde:

From the online AMS glossary: “An expendable meteorological instrument package, often borne aloft by a free-flight balloon, that measures, from the surface to the stratosphere, the vertical profiles of atmospheric variables and transmits the data via radio to a ground receiving system. Radiosondes typically measure temperature, humidity and, in many cases, pressure. Radiosonde temperature sensors generally measure temperature-induced changes in the electrical resistance, capacitance, or voltage of a material. Radiosonde humidity sensors can be substances that respond in a known way to changes in ambient humidity or instruments that directly measure a characteristic of the air that is dependent on its water vapor content. Radiosonde pressure sensors are typically aneroid cells, a part of which flexes in proportion to pressure changes. Some radiosondes do not measure pressure, but pressure data are calculated from the hypsometric equation using temperature, humidity, and height data. Some radiosondes also measure wind speed and direction.”

GFS:

Global Forecast System.  A global model, it is a product of NCEP, the National Centers for Environmental Prediction.  The model was formerly known as AVN/MRF, which stands for Aviation Model Forecasts / Medium Range Forecast model.  The latest upgrade (made 31 May2005) increased the resolution to T382 (which equates to about 40km) with 64 levels in the vertical and out to 180 hours (7.5 days).  After that it has a resolution of T190 (~80km) and 64 levels and it goes out to 384 hours (day 16).

GOES West:

Geostationary Operational Environmental Satellite. NOAA’s operational satellite over the United States’ west coast, GOES West is positioned above the Pacific Ocean at 135 degrees West longitude.

Profiler:

From the online AMS glossary: “A remote sensing device that receives electromagnetic (or acoustic) waves transmitted through, emitted by, or reflected from the atmosphere in order to produce a vertical profile of one or more atmospheric quantities.” The Fort Ord profiler measures winds at 915 mb and provides both a vertical profile of winds over the sensor, as well as virtual temperatures above the sensor.

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3

2

1

In port

0

50

550

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385

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18 Jul 05

Tuesday

19 Jul 05

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20 Jul 05

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21 Jul 05

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22 Jul 05

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23 Jul 05

12 18 00 06

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* *

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00 06 12 18

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00 06 12 18

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Day

Date

Local Time

Sondes

GMT

Cloud Top Height

(m)

1

2

3

Figure 2: from Lentz: Spring Transition over the Northern California Shelf (Fig 2)

1

Mon 18 Jul 05

Tues 19 Jul 05

Wed 20 Jul 05

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19 July 05 10:19:59Z

03:19:59L

18 July 05

20:46:45Z

13:46:45L

300mb

12z, 19 July 05

500mb

19 July 05 10:19:59Z

03:19:59L

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18 July 05

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22 July 05 05:01:23Z

21 July 05

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22 July 05 00:01:38Z

21 July 05

17:01:38L

Figure 3: Fort Ord profiler data from 18-21 July 2005

Figure 1: Cloud top heights compared to radiosonde launch times during OC3570 cruise on R/V Pt Sur.

Table 1: Sonde launch times and associated cloud top heights (measured in meters).

Figure 5: Case One: 300mb and 500mb GFS analyses over GOES West satellite imagery.

Figure 4: Case One: Temperature and dew point profiles from radiosonde soundings three and four.

Figure 7: Case Two: Temperature and dew point profiles from radiosonde soundings fourteen and fifteen.

Figure 6: Case One: M-profiles from radiosonde soundings three and four.

Figure 8: Case Two: M-profiles from radiosonde soundings fourteen and fifteen.

3

23 July 05 06:44:55Z

22 July 05

23:44:55L

23 July 05 00:57:14Z

22 July 05 17:57:14L

2

00z, 22 July 05 ((96)

12z, 21 July 05 ((84)

Figure 10: Case Two: M-profiles from radiosonde soundings fourteen and fifteen.

Figure 11: Case Three: Temperature and dew point profiles from radiosonde soundings twenty and twenty-one.

300mb

12z, 23 July 05

500mb

300mb

00z, 23 July 05

500mb

300mb

12z, 22 July 05

500mb

3

Figure 12: Case Three: 300mb and 500mb GFS analyses over GOES West satellite imagery.

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23 July 05 00:57:14Z

22 July 05 17:57:14L

23 July 05 06:44:55Z

22 July 05

23:44:55L

Figure 13: Case Three: M-profiles from radiosonde soundings twenty and twenty-one.

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