2002: Storms in the Future: Relating Changes in Intensity, Cloudiness, Rainfall and Economic Costs

Team Members: Shaynah Browne, Ali Mirza, Amelia Prasad, Keith Moranice, Zelma Ortiz, Chris Petersen, George Tselioudis

Introduction

This project deals with the question of how storm conditions in the world's middle latitudes, with emphasis in the Northeastern and Midwestern sections of the United States, will be different in a possible future warmer climate, and what the economic impacts of these differences may be. In the midlatitude regions, where most of the world's population lives, the major weather-makers are midlatitude storms. These large-scale storms mix cold and warm air masses to produce high winds, clouds, and precipitation. The winds and the precipitation (and the lack of precipitation in some cases) have a direct economic impact on the people living in these regions. In order to explore how different the midlatitude weather of a warmer world will be from the weather that we experience today, it is important to understand how the properties of midlatitude storms may change as climate warms.

Midlatitude storms are disturbances that form along the jet-stream (the river of air that circumnavigates the globe in the Northern and Southern midlatitudes) and travel with it in an eastward direction. The jet-stream owns its existence and draws its energy from the large temperature differences that exist between the Earth's equator and poles. In a warmer climate, the temperature difference between those two regions will be smaller and this may result in a slower, less energetic jet-stream. Does this mean that a warmer world will experience fewer or weaker midlatitude storms? Keep in mind that storms are fueled by the presence of humid air masses in their path, a condition that will be more prevalent in a warmer climate. Evidence obtained from our group's previous research, and substantiated by other researchers in the field (McCabe, G., Clark, M., and Serreze, Mark, 2001: Trends In Northern Hemisphere Surface Cyclone Frequency and Intensity, Journal of Climate, 14, 2763 - 2768) indicates that if the climate continues to warm, fewer storms will occur in the midlatitudes; however, the same evidence also suggests there may be a small increase in the frequency of the strongest, most extreme storms.

Fewer storms overall might imply a smaller economic impact due to decreased damages from less rain and wind. On the other hand, an increase in the frequency of the strongest storms may imply more damages and an even greater economic impact. Which properties of storms and their clouds are most closely related to the damages inflicted by these storms? In our attempt to profile the economic impacts of the storm of the future, our group will build on the knowledge that has been gained from studying the storms of the past and on predictions made using the GISS climate model. We have developed tools that scan weather data to locate and track midlatitude storms as well as tools that collocate and correlate storm and cloud properties from weather and satellite observations, and we have developed a thirty-year climatology of storms. We will use those tools to fulfill the following objectives:

• Examine how the presence of a stronger or a weaker storm changes the probability that a person on the ground will experience thinner-drizzling, or thicker-raining clouds.
• Examine existing data sets for trends in changing cloud properties and precipitation in the Northeastern and Midwestern United States over the past 15 years.
• Use insurance records to examine how storm-related damage (property and agricultural) costs have been changing in those two US regions over the last 15 years and how these cost changes may relate to variations in storm and cloud properties.

Combining the different parts of our analysis we will attempt to resolve how the changing frequency and strength of midlatitude storms will influence the properties of the storms and their clouds, what such changes will mean in terms of the everyday weather conditions in the midlatitude regions, and how these weather conditions may translate into economic impacts.

Guiding Science Questions and Related Research Tasks

How does the intensity of a storm relate to the properties of the clouds and the amount of rain produced by the storms in the Northeastern and Midwestern United States?

Task: Examine storm observations and relate the intensity of the storms in the Northeastern and Midwestern United States with the properties of the clouds and the amounts of precipitation.

How have the average cloud properties and the amount of rain produced by the storms in the Northeastern and Midwestern United States been changing over the past 15 years?

Task: Examine cloud and precipitation observations from the past 15 years in the Northeastern and Midwestern United States and look for trends in the average properties of the clouds and the amounts of precipitation.

How has economic damage (property and agriculture) from storms been changing in the last 15 years in the Northeastern United States?

Task: Plot trends of storm damage for the Northeastern United States over the last 15 years.

How has economic damage (property and agriculture) from storms been changing in the last 15 years in the Midwestern United States?

Task: Plot trends of storm damage for the US Midwestern United States over the last 15 years.

How are storm damage costs in the Northeastern and Midwestern United States related to the properties of the storms and the clouds of those storms in these regions?

Task: Examine periods of high and low storm damages and compare the properties of the clouds and the storms during those periods.

Related Science Principles

The significance of high and low pressure systems in the atmosphere

The role of the Coriolis force and pressure gradient force

The relationship between atmospheric pressure gradient and wind speed/direction

The cloud formation processes and the condensation of water vapor

Related Mathematical Skills

Determining averages for quantities varying over time and/or spatial domains.

Describing variations of quantities over time and/or space.

Determine the significance, or the lack of significance of observed trends in these variations.

Related Technical Skills

Use Spyglass Software to determine statistical quantities (averages, maximums, minimums, etc.) over large regions, including situations in which data is not available over the entire region.

Use Excel software to examine statistical quantities over periods of time in order to search for trends in variability of these quantities.

Procedure to Encourage the Development of these Skills

The development of these skills and knowledge by the students will be an ongoing process through the summer and beyond.

Science principles will be addressed during the first week of the program. This will be done by first having a general discussion with the students to determine their current levels of understanding, followed by some suggested readings aimed at addressing areas that need to be strengthened, and finally mini-lessons by George and Chris.

The mathematical and technical skills will be developed when the research tasks require these particular skills. When students need to use a new skill they will be introduced to the skill by the alumni students or the faculty through mini-tutorials. These skills will then be enhanced through repeated practice as the research process continues throughout the summer.