MSA: Modeling and Forecasting Shifts in Migratory Patterns Under Changing Hadley Circulation Dynamics

每年，数以亿计的昆虫、鸟类和蝙蝠从中美洲和南美洲经墨西哥飞到美国和加拿大。这些迁徙是自然界最壮观和最明显的现象之一。然而，年复一年地启动和引导这些迁徙的因素仍然知之甚少，特别是对昆虫。已知的一个重要因素是盛行风的方向和强度，这在很大程度上是由大气环流单元决定的，但人们对此还不是很清楚。这些细胞是主要的环境驱动力，不仅影响着盛行的风的模式，而且还影响着地球上生态生物群的位置。其中最大的一个被称为哈德利环流，活动在大约从S纬度30°到北纬30°的热带地区。在这个环流环流中，风围绕赤道上升，然后在较高的高度同时向北和向南移动。当它们落到热带边缘更近的地面上时，它们带来了干燥的空气，但也可能携带着移民。帝王蝶(Danaus Plexippus)是最著名的昆虫迁徙物种，它们在墨西哥哈德利细胞上升气流的焦点附近越冬，向北迁徙到德克萨斯州产卵，靠近哈德利细胞下沉的地方。然而，到目前为止，哈德利细胞和帝王迁徙之间的联系还没有得到探索。这项研究将考察哈德利细胞在包括帝王蝶在内的八种蝴蝶年度迁徙动态(时机和成功)中的作用，这些蝴蝶跨越墨西哥迁徙到美国。这项工作将开发适用于理解全球空中移民的移民模型/教育模块。研究结果将通过研究团队运营的三只蝴蝶网站在利益相关者和公众之间分享，研究结果也将被纳入乔治城大学关于数量生态学的定期讲座。迁徙解释了全球生态系统中营养物质和生物量的大量转移，也为物种生存提供了关键战略。然而，由于迁徙的空间范围很大，研究它是一个特别具有挑战性的现象。鉴于温度、降水和风等环境驱动因素对迁徙的重要性，环境变化可能会对动物迁徙产生重大影响，特别是对昆虫。这项研究将开发一个使用全球大气环流单元来理解长距离迁移的框架。模型将使用美国西南部国家生态观测网(NEON)的七个站点的数据以及几个公民科学蝴蝶监测网的数据进行验证。此外，该团队将使用气候模型将这些模式投射到不同气候情景下的未来。这项研究的具体目标是量化最大的大气环流单元--哈德利环流细胞--在多大程度上支持从热带向温带迁徙的昆虫离开、迁徙和到达的机械动力学。这项工作将模拟8种蝴蝶物种的迁徙，其中3种显示了典型的往返迁徙(例如，帝王蝶)，其余5种仅在秋季进行单向迁徙。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Every year billions of insects, birds, and bats fly from central and South America through Mexico up into the United States and Canada. These migrations are one of the most spectacular and visible phenomena of the natural world. Yet factors that initiate and guide these migrants year after year remain poorly understood, especially for insects. One factor that is known to be important, but not well understood, is the direction and strength of prevailing winds, which are largely determined by atmospheric circulation cells. These cells are dominant environmental drivers impacting not only the pattern of prevailing winds, but also the location of ecological biomes across the Earth. The largest of these cells, called the Hadley cell, operates in the tropical zone approximately from latitude 30°S to 30°N. In this cell, winds rise around the equator and then move both North and South at higher altitudes. As they fall to the ground closer at the edge of the tropics, they bring dry air, but also potentially carry the migrants. Monarch butterflies (Danaus plexippus), the best-known insect migrant, overwinters in Mexico, near the focal point of the Hadley cell updraft and migrates North to lay eggs in Texas, near where the Hadley cell subsides. Yet the connection between Hadley cell and monarch migration to date has not been explored. This study will examine the role of the Hadley cell in the annual migratory dynamics (timing and success) of eight species of butterflies, including monarch, that migrate across Mexico and into the US. This work will develop migration model / educational modules that will be applicable for understanding aerial migrant across the globe. Results will be shared among the stakeholders and public through the three-butterfly websites run by the research team, and the results will also be incorporated into the regular lectures on quantitative ecology at Georgetown University.Migration accounts for massive transfers of nutrients and biomass in ecosystems worldwide and also provides a key strategy for species survival. Yet migration is a particularly challenging phenomenon to study due to its large spatial extent. Given the importance of environmental drivers such as temperature, precipitation, and wind for migration, environmental change may have substantial impacts on animal migration, particularly for insects. This study will develop a framework using global atmospheric circulation cells to understand long-distance migration. Models will be validated using data from seven sites of the National Ecological Observatory Network (NEON) in the southwestern US and also with data from several citizen science butterfly monitoring networks. Further, the team will use climate models to project these patterns into the future under different climate scenarios. The study’s specific objectives are to quantify the degree to which the largest atmospheric circulation cell, the Hadley Cell, underlies the mechanistic dynamics of departure, migration and arrival for insects migrating from the tropics to the temperate zone. This work will model migration of eight butterfly species, three of which show classic round-trip migration (e.g., monarch) and the remaining five migrate one-way only in the fall.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.