Characterization of Pollen Particles Using LIDAR

We have observed pollen in the local troposphere using the depolarization capabilities of a LIDAR (Light Detection and Ranging) system. The polarization characteristics of the received LIDAR signal, along with supplemental pollen forecast data, allowed me to characterize the shape of the pollen particles

Results from an Extremely Sensitive Rayleigh-Scatter Lidar

Rayleigh-Scatter lidar systems effectively use remote sensing techniques to continuously measure atmospheric regions, such as the mesosphere (45-100km) where in situ measurements are rarely possible. The Rayleigh lidar located at the Atmospheric Lidar Observatory (ALO) on the Utah State campus is currently undergoing upgrades to make it the most sensitive of its kind. Here, the important components of these upgrades and how they will effect the study of a particular atmospheric phenomena, atmospheric gravity waves, will be discussed. We will also summarize what has been done to the system during this year to bring us to the threshold of initial operations

Middle Atmosphere Temperature Results from a New, High-powered, Large-Aperture Rayleigh Lidar

In June–July 2012, observations were carried out using the recently upgraded, large-aperture, Rayleigh-scatter lidar system located at the Atmospheric Lidar Observatory (ALO) on the campus of Utah State University, in Logan, UT (41.7 N, 111.8 W). This time period was significant because it enabled us to observe the annual temperature minimum in the upper mesosphere-lower thermosphere region. The data collected during the campaign were analyzed for temperatures between ~70–109 km. The results above ~95 km are the first obtained with a Rayleigh-scatter lidar, extending the technique well into the lower thermosphere. A great deal of variability from night-to-night is evident in these temperature profiles and in the mesopause altitude. The profiles also show considerable wave activity from large amplitude waves. The temperatures are compared to those from the MSISe90 model and from the 11-year ALO temperature climatology. This new capability for the ALO Rayleigh lidar, like any new observational capability, opens the potential for new discoveries in this hard-to-observe region

Rayleigh Scatter Lidar Observations of the Midlatitude Mesosphere’s Response to Sudden Stratospheric Warmings

The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU) collected a very dense set of temperature data for 11 years, from 1993 through 2004. The temperatures derived from these data extended over the mesosphere, from 45 to 90 km. This work will focus on the extensive Rayleigh lidar observations made during the seven major SSW events that occurred between 1993 and 2004. In order to determine the characteristics of the midlatitude mesospheric temperatures during SSWs, comparisons were made between the temperature profile on an individual night during a SSW event and the climatological (11-year average) temperature profile for that night. An overall disturbance pattern was observed in the mesospheric temperatures during these SSWs. It included coolings (sometimes very significant) in the upper mesosphere and warmings in the lower mesosphere

Midlatitude Mesospheric Temperature Anomalies During Major SSW Events as Observed with Rayleigh-Scatter Lidar

While the mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions, observations of these anomalies at midlatitudes are sparse. The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU) collected a very dense set of temperature data for 11 years, from 1993 through 2004. The temperatures derived from these data extended over the mesosphere, from 45 to 90 km. This work focuses on the extensive Rayleigh lidar observations made during seven major SSW events that occurred between 1993 and 2004, and aims to compile a climatological study of the midlatitude mesospheric temperatures during these SSW events. In order to determine the characteristics of the midlatitude mesospheric temperatures during SSWs, comparisons were made between the temperature profile on an individual night during a SSW event and the climatological (11-year average) temperature profile for that night. An overall disturbance pattern was observed in the mesospheric temperatures during these SSWs. It included coolings in the upper mesosphere, comparable to those seen in the polar regions, and warmings in the lower mesosphere

Connection between the midlatitude mesosphere and sudden stratospheric warmings as measured by Rayleigh-scatter lidar

While the mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions, observations of these anomalies at midlatitudes are much more sparse. The Rayleigh-scatter lidar system, which operated at the Center for Atmospheric and Space Sciences on the campus of Utah State University (41.7°N, 111.8°W), collected a very dense set of observations, from 1993 to 2004, over a 45–90 km altitude range. This paper focuses on Rayleigh lidar temperatures derived during the six major SSW events that occurred during the 11 year period when the lidar was operating and aims to characterize the local response to these midlatitude SSW events. In order to determine the characteristics of these mesospheric temperature anomalies, comparisons were made between the temperatures from individual nights during a SSW event and a climatological temperature profile. An overall disturbance pattern was observed in the mesospheric temperatures associated with SSW events, including coolings in the upper mesosphere and warmings in the upper stratosphere and lower mesosphere, both comparable to those seen at polar latitudes

The Mid-Latitude Mesosphere’s Response to Sudden Stratospheric Warmings as Determined from Rayleigh Lidar Temperatures

The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), collected temperature data for 11 years, from 1993 through 2004. The temperatures derived from these data extended over the mesosphere, from 45 to 90 km. Recently, they were combined with other observations to examine the mid-latitude responses to Sudden Stratospheric Warmings (SSWs) in the polar regions. (The other observational instruments being an ionosonde, a meteor wind radar, a Na lidar, and a satellite.) Extensive Rayleigh lidar observations were made during a dozen SSW events. In order to look for effects of the SSWs, comparisons were made between the temperature profile on individual nights during an SSW event and the climatological temperature profile for that night of the year. An overall disturbance pattern was observed in the mesospheric temperatures during northern hemisphere SSWs. It included coolings (sometimes very significant) in the upper mesosphere and warmings in the lower mesosphere. Examples of the effects in the mesosphere from southern hemisphere SSWs are also given

Seasonal Variations of Relative Neutral Densities between 45 and 90 km Determined from USU Rayleigh Lidar Observations

A Rayleigh-scatter lidar operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W), part of Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), collected extensive data between 1993 and 2004. From the Rayleigh lidar photon-count profiles, relative densities were determined throughout the mesosphere, from 45 to 90 km. Using these relative densities three climatologies were derived, each using a different density normalization at 45 km. The first normalized the relative densities to a constant; the second to the NRL-MSISe00 empirical model which has a strong annual component; and the third to the CPC analyses model, which is similar to MSIS in that it has a strong annual oscillation. In each case the density profile for every night of a composite year was found by averaging the nighttime density profiles over a 31-day by 11-year window centered on that day. For each of the cases, the average annual density profile was found by averaging all the days. Then the daily percent differences were found relative to the annual density profile. Despite the different normalizations at 45 km, many common features were found in the seasonal behavior of the density profiles, a large seasonal variation maximizing in June at ~70 km, Another above 80 km is a large shift in the maximum to earlier in the year, and lastly sharp density fall off at almost all altitudes in early October. While these density normalizations provide initial information about mesospheric behavior, the current lidar upgrade will enable us to add an absolute scale to the density profiles