| 1. |
- Banik, Trisanu, et al.
(författare)
-
Understanding dynamics of tropical cyclones in the Bay of Bengal using lightning data
- 2021
-
Ingår i: Meteorology and atmospheric physics (Print). - : Springer Nature. - 0177-7971 .- 1436-5065. ; 133:5, s. 1505-1522
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work, we are studying the dynamics of 11 tropical cyclones (TCs) over the Bay of Bengal (BoB) using the World Wide Lightning Location Network (WWLLN) lightning data during 2013–2017. Detailed investigation of Lightning Stroke Count (LSC) shows that the initial phase of the TC intensification over BoB is associated with high lightning activity both in the eye region and rainband region. The study of different category TCs shows the weak and moderate-intensity TCs during both in pre-monsoon and post-monsoon seasons are lightning populated (specifically inner bands) during and prior to the intensification phase. Peak Maximum Sustained Wind Speed (MSWS), which is linked to sea surface temperatures (SSTs), is preceded by the peak LSC with a time lag of 6–12 h. The LSC peaks in the eye region and rain band for different categories of TCs between small to moderate wind shear range. The present study highlights that the monitoring of real-time lightning activity could provide supportive information on the existing forecast techniques. But further analyses are required over BoB to quantify the relationship between TC intensification and lightning activity both in space and time.
|
|
| 2. |
- Warren, Jeffrey M., et al.
(författare)
-
Divergent species-specific impacts of whole ecosystem warming and elevated CO2 on vegetation water relations in an ombrotrophic peatland
- 2021
-
Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 27, s. 1820-1835
-
Tidskriftsartikel (refereegranskat)abstract
- Boreal peatland forests have relatively low species diversity and thus impacts of climate change on one or more dominant species could shift ecosystem function. Despite abundant soil water availability, shallowly rooted vascular plants within peatlands may not be able to meet foliar demand for water under drought or heat events that increase vapor pressure deficits while reducing near surface water availability, although concurrent increases in atmospheric CO2 could buffer resultant hydraulic stress. We assessed plant water relations of co-occurring shrub (primarily Rhododendron groenlandicum and Chamaedaphne calyculata) and tree (Picea mariana and Larix laricina) species prior to, and in response to whole ecosystem warming (0 to +9 degrees C) and elevated CO2 using 12.8-m diameter open-top enclosures installed within an ombrotrophic bog. Water relations (water potential [psi], turgor loss point, foliar and root hydraulic conductivity) were assessed prior to treatment initiation, then psi and peak sap flow (trees only) assessed after 1 or 2 years of treatments. Under the higher temperature treatments, L. laricina psi exceeded its turgor loss point, increased its peak sap flow, and was not able to recover psi overnight. In contrast, P. mariana operated below its turgor loss point and maintained constant psi and sap flow across warming treatments. Similarly, C. calyculata psi stress increased with temperature while R. groenlandicum psi remained at pretreatment levels. The more anisohydric behavior of L. laricina and C. calyculata may provide greater net C uptake with warming, while the more conservative P. mariana and R. groenlandicum maintained greater hydraulic safety. These latter species also responded to elevated CO2 by reduced psi stress, which may also help limit hydraulic failure during periods of extreme drought or heat in the future. Along with Sphagnum moss, the species-specific responses of peatland vascular communities to drier or hotter conditions will shape boreal peatland composition and function in the future.
|
|
