Research Results
Clouds Over Storm Lifecycles
Displaying Cloud Data for Easy Interpretation
Clouds are one of the most important temperature regulators of the earth. It is known, for example, that low thick clouds cool the earth. If these low thick clouds increase due to climate change, the warming problem could essentially be undone. On the other hand, if they decrease, the problem will worsen. The study of clouds, however, is difficult when the data pertaining to clouds is not easily accessible for interpretation. The purpose of this research project is to facilitate the visualization and manipulation of cloud data to allow its easy interpretation. This is accomplished through a series of mini-applications (or applets) which access the raw data and then display the data using a color scheme. They also allow the user to select areas of the data set for a more indepth study of that area. The applets are written in the Java programming language and embeded in Hypertext Markup Language (HTML) documents (or Web pages) to allow Internet usage. The applets are developed by means of a Java Integrated Development Environment (IDE) which makes the development of Java programs faster and easier. The results are reliable, error-free applets that provide insight into many cloud intricacies allowing cloud research to proceed smoothly.
The Role of Clouds In Midlatitude Storms
Clouds can either heat or cool the earth. High thin clouds trap radiation generating a warming effect. Low thick clouds reflect solar radiation creating a cooling effect. Mid-Latitude storms generate large amounts of clouds. NASA scientists simulate storms in their Global Climate Model (GCM). However, they're not sure how storm factors such as sea level pressure and wind speed contribute to different types of clouds. By studying the production of different clouds in actual storms from April 1988 we formed hypotheses which may help improve the GCM. To study storms we used an application that displays International Satellite Cloud Climatology Project (ISCCP) satellite data; optical thickness, cloud top pressure, and weather station data; such as sea level pressure and surface tempurature. We compared cloud optical thickness and cloud top pressure to find the location of certain clouds; we also identified the sea level pressure to classify the storms by strength. To develop a storm factor, we used sea level pressure and wind strength, which determine the strength of a storm and compared that data to the percentage of rain clouds in storms. Our analysis found that the thinnest mid-altitude clouds reside around warm fronts. From our comparison of the storm factor and the percent of deep convective rain clouds we found that, similar to hurricanes, as mid-latitude storms get stronger more rain clouds are formed. By comparing the storm factors and the percentage of deep convective clouds we found that if stronger storms occur in the future they will produce more rain clouds.
Is There a Relationship between Cloud Properties and Storm Strength in Tropical Storms?
Hurricanes are one of the most destructive tools of nature. Humans can also use them as tools, to study how physical characteristics of the storms are related to the properties of the clouds produced by those storms. Clouds are known to have effects on the Earth's global temperature. Low thick clouds block solar radiation and have little effect on infrared radiation due to the small temperature difference between the cloud and the surface. This produces a cooling effect. High thin clouds cause warming effects. Tropical storms (hurricanes) follow the idea of a perfect storm, with a low sea level pressure, a compact size, and a cyclonic behavior. They are easily isolated for analysis. By better understanding how the strength of tropical storms interact with their cloud properties similar questions for larger, more complex storm systems like mid-latitude storms, the major cloud producers, may be found. I investigated ten tropical storms in order to examine the relationship between the storm properties and the properties of the clouds produced by the storms. I used satellite data for the cloud properties and ground based data for the storm properties. I compared two cloud properties: cloud optical thickness and cloud top pressure (height), to four storm properties: maximum wind speed, minimum sea level atmospheric pressure, tracks and the storm's life cycle in order to discover any correlations between these properties. My analysis showed that in the first and second stage of the tropical storms as the strength increases the amount of deep convective (high thick) clouds also increases. I saw the opposite effect in the third stages of these storms. I also observed that storms dying out over land had a greater amount of deep convective clouds than storms that died over water. During the lifecycle of these storms the amount of deep convective clouds increased from the first to the second stage and decreased during the third stage. In the future if more strong storms occur they will result in a greater amount of thick clouds which can lead to global cooling. These findings may also prove useful in the analysis of more complex systems like mid-latitude storms.
The Significance of Clouds Produced by Mid-latitude Storms
Clouds will have an effect on future global climate change. High, thin clouds act as a warming blanket by letting most of the sunlight through and trapping heat from the surface. Low thick clouds let only a small amount of sunlight through and therefore have a cooling effect. Scientists use computer models to predict how clouds might affect climate change, but are unsure of how clouds are formed in real storms. Mid-latitude storms are the major producers of clouds. We need to investigate the cloud types made by these storms and how these clouds are formed before being able to suggest improvements to the NASA/GISS computer climate model. We used weather station data to identify storms based on low sea-level atmospheric pressure and to locate where the cold and warm fronts were for each storm. We used satellite-imaging data to classify cloud types. Finally we attempted to relate these cloud types to the general characteristics of storms. Our most significant findings were that generally the thickest clouds of a storm form along or near the cold front. The thinner clouds tend to form along or near the warm front of a storm. We also observed that the amount of rain clouds in a mid-latitude storm increases with the strength of the storm and it was a high correlation. Our results will enable us to compare the computer climate model's storms to real world storms and determine if the model produces similar storm cloud distribution. Our results already show a similarity between hurricanes and mid-latitude storms, in that more rain clouds are produced with stronger storms.
Do Stronger Storms Occur Under Conditions Similar To Global Warming?
Several computer programs that simulate planetary climate conditions predict that if global warming occurs there will be a decrease in the overall number of storms that occur. This will be accompanied by an increase in the occurrence of the strongest storms. Will this happen in the real world? We hypothesize that by comparing years in the real world during which conditions resemble those under global warming with years that are more normal, we can approximate the changes that the earth may experience under global warming. We defined a storm's strength in terms of the minimum sea level atmospheric pressure that occurs during that storm. We examined the sea level pressure for the entire globe from 1979-1996 and determined the distribution of storm strengths for each month. We then examined the surface temperatures to select five winters that exhibited characteristics most similar to those under global warming and five winters that were more similar to normal conditions. We compared the total storm distribution in both categories to highlight the changes in storm intensities that may occur during global warming. Unlike the predictions made by the models, we observed that more storms overall were produced during warming conditions, due mainly to an increase in the number of weaker storms. There was however, an increase in the number of strongest storms during the years with warming conditions as predicted by the model. Our results are inconclusive. This may be due to the fact that there were no significant climate changes during this time period. We may need to examine changes over a longer time period, or reexamine our definition of a storm before being able to determine the validity of our hypothesis.
Jose Alburquerque is a student at the City College of New York; Sharika De La Oz, Juan Clavijo, and Andrew Audry are students at A. Philip Randolph High School; Christopher Petersen is a teacher at A. Philip Randolph High School; and Jericco Tolentino is a student at Brown University. (August 1998)
1998 Abstracts :
Forcings and Chaos ||
Oceans ||
Radiation ||
Clouds
Impacts ||
Methane ||
Aerosol Emissions ||
Pollen
