Week 10: Extreme Weather

While circulation changes are mostly responsible for changes in the average amount of precipitation, extremes are far more susceptible to the thermodynamic state and conditions on certain days. Extremes can only happen when numerous preconditions come together. Extreme rainfall, for instance, necessitates enhanced ("potential") moisture transport into the area, high temperatures (or strong temperature gradients), and severe atmospheric instability. It is comparatively uncommon for these "ingredients" to align. A combination occurrence can also be more likely if that one condition—higher temperatures—is met more frequently. The Clausius-Clapeyron Relationship states that for every 1 degree Celsius increase in air temperature, that air's capacity to carry moisture increases by 7%. This makes warmer temperatures particularly significant for precipitation. As a result, the warmer the air, the more moisture it can hold; as a result, if rain formed, much more water could be extracted from it.

The following are Puerto Rico's all-time extremes. On October 7th, 1985, the Toro Negro Forest received 23.75 inches of rainfall during a 24-hour period. The record-breaking high temperature was 104 degrees, which was recorded on Mona Island on July 2, 1996. On March 9th, 1911, Aibonito recorded the coldest temperature ever, which was 40 degrees. 

Despite being susceptible to earthquakes, tsunamis, and wildfires, tropical storms and drought pose the greatest threat of disaster to Puerto Rico. Long-term drought affects cattle, agriculture, and water supplies while raising the danger of wildfires. Maria was the most powerful tropical storm to strike Puerto Rico since 1928. Extreme drought that affected much of the larger Caribbean region from 2014 to 2016 also affected Puerto Rico. In Puerto Rico, 2015 was the third driest year. Businesses were briefly shuttered, there were tight water restrictions in place, and crops and livestock were lost.

The wettest months in Puerto Rico are April through November, and the driest months are December through March. Because of the geography of the island, annual rainfall varies substantially from Magueyes Island's 29.32 inches to Pico del Este's 171.09 inches on average. 

In September, Puerto Rico experienced its most recent heat wave, recording a record-breaking 47 nights with temperatures exceeding 80 degrees Fahrenheit. When asked if their classrooms had air conditioning during the heat wave, 83% of instructors responded that they did not.

https://climateknowledgeportal.worldbank.org/country/puerto-rico/extremes

https://www.weather.gov/sju/climo_extremes

https://www.climatehubs.usda.gov/hubs/caribbean/topic/disaster-preparedness-puerto-rico-and-us-virgin-islands#:~:text=Though%20vulnerable%20to%20earthquakes%2C%20tsunamis,%2C%20tropical%20storms%2C%20and%20drought.

https://www.nbcnews.com/news/amp/rcna103923

Week 8: Mass Wasting Hazards (Landslides)

On September 20, 2017, Hurricane Maria struck the island of Puerto Rico, causing more than 40,000 landslides in at least three-fourths of Puerto Rico's 78 municipalities. The majority of landslides were shallow, but there were occasionally deeper ones as well. These occurred before, during, and following flooding, and many developed into extended runout debris flows. Due to the already wet soils, steep slopes in hilly and mountainous areas were severely affected by landslides. 

The USGS Landslide Hazards Program seeks to lessen the effects of landslides on people and infrastructure by advancing people's knowledge of the causes of ground failure and by suggesting risk-reduction measures. USGS researchers have carefully examined rainfall-induced landslides in Puerto Rico to produce maps showing landslide susceptibility. Residents and emergency managers have access to educational resources that present scientific ideas in an understandable manner. The USGS has been closely collaborating with local partners to study landslides caused by significant rainfall events like Hurricane Maria in order to better understand rainfall-induced landslides in Puerto Rico. Scientists can depict landslide parameters like magnitude, failure mode and style, mobility of debris slides, flows of geologic material, location, and timing using remote sensing techniques and field observations. Local scientists and USGS scientists have collaborated to calculate landslide risk using this data as well as other crucial variables like proximity to roads and streams. The stream system experienced a high volume of eroded soil from the landslides. This sudden shift in chemical weathering measurements over a brief span of time does not suggest a significant alteration in climate. Instead, it is likely due to minor changes in the way landslides transport sediment to streams. When cations from silicate weathering combine with carbonate minerals downstream, even small landslides can have a significant impact on carbon sequestration, as seen in the post-hurricane changes in stream chemistry.

https://www.usgs.gov/supplemental-appropriations-for-disaster-recovery-activities/landslides-triggered-hurricane-maria

https://www.usgs.gov/mission-areas/natural-hazards/science/puerto-rico-natural-hazards-landslides-peligros-naturales-de

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021JF006509