CCGA reminds farmers that repayments on existing advances must be made every time a farmer sells a commodity that is associated with their advance, including advances that are eligible for the Stay of Default. In addition, advances that include an interest-bearing portion will continue to accrue interest throughout the extension. Farmers who have questions about their cash advance or the Stay of Default are encouraged to contact CCGA at International Conference on Aviation Management and Information Technology ICAMIT Addis Ababa , 28th September The aim of the Conference is to provide a platform to the researchers and practitioners from both academia as well as industry to meet the share cuttingedge development in the field.
View More. International Conference on Innovative Engineering Technologies ICIET Cairo , 28th September The aim of the Conference is to provide a platform to the researchers and practitioners from both academia as well as industry to meet the share cuttingedge development in the field.
International Conference on Automation Science and Engineering ICASE Harare , 29th September The aim of the Conference is to provide a platform to the researchers and practitioners from both academia as well as industry to meet the share cuttingedge development in the field. Whether simultaneously or not, I am unable to say. On the Boundary Commission maps drawn ca. These historical observations are consistent with the tree-ring dating of lake-level rise in an ice-marginal lake basin that is adjacent to the Brady Glacier Figures 1 , 4 , 5e where Capps et al. CE Goodwin, By that year, the terminus had retreated some 15 km behind its LIA limit, and a rapid retreat ensued by ca.
Widespread advances of coastal glaciers occurred along the northeastern coastline of the GOA during the 19th century. The geometry and bathymetry of these three fjords, their exposure to tidewater, and their present strongly positive mass balances suggest their recent dynamics have been dominated by calving glacier cycles, which has reduced the influence of climate on their advances and retreats. Overall, the 19th century seems to have been a time of widespread positive mass balance for those coastal glaciers not caught within calving glacier cycles.
Glacier advances during the 19th century were also widespread among non-tidewater glaciers in the GOA region Figure 6.
This broad synchronicity between land-terminating and tidewater glaciers suggests that climate, rather than idiosyncratic glaciological factors relating to the calving glacier cycle, was the probably the main driver of 19th-century glacier advances along the northeastern GOA. Figure 6. Note that most of the Coastal Alaska glaciers advanced shortly after the Dalton Minimum, which was relatively minor in terms of solar forcing and summertime cooling.
In these North Atlantic regions, most glaciers reached maximum LIA extents earlier during the LIA and either re-advanced or remained in advanced positions until ca. CE Grove, More similar to the GOA record are those from the western interior region of Canada and from the Pacific Northwest, where most glaciers reached their LIA maxima in the early 18th century, and several others reached their LIA maxima in the midth century Burbank, ; Heikkinen, ; Luckman, ; Luckman, ; Larocque and Smith, ; Lewis and Smith, ; Allen and Smith, ; Jackson et al.
These differing geographic patterns suggest that the global causes of the LIA were strongly modified by idiosyncrasies involving glaciological responses to regional climate processes. Although the GOA glacier record involves both calving and non-calving glaciers, the fact they are relatively small, warm-based glaciers with large mass balances suggests their lag times in response to climate are on the time scale of several decades Bahr et al.
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Thus we can use regional climate records from the period CE to to infer the identity of climate drivers of glacier fluctuations during this same period. Summer cooling caused by the combination of Milankovitch forcing and solar minima associated with the De Vries Cycle have been important drivers of the LIA glacier record in Alaska Wiles et al. Glaciers in the hypermaritime region of coastal Alaska may be particularly sensitive to solar-affected air temperatures because of the effects that temperature has on both the length and the warmth of the ablation season within the relatively mild climate in this maritime setting Oerlemans and Fortuin, ; Oerlemans, Despite the general pattern of glaciers advancing in response to the cooling caused by orbital forcing and solar minima, it remains unresolved why the frequency and extent of LIA glacier advances along the GOA coastline do not correspond with the length and intensity of solar minima.
For example, the most prominent, and, in many cases, the most extensive LIA glacier advances occurred during the 19th century Wiles et al.
Although the Dalton Minimum was relatively cool based on the tree-ring-based reconstruction of February-August air temperatures Figure 6 ; Wiles et al. Furthermore, the 19th century advances of the La Perouse Glacier and other glaciers in the region followed a slight multi-century warming trend in mean Feb-Aug temperatures that began ca. CE Figure 6. It therefore seems unlikely that cooler summer temperatures alone account for the relatively late LIA advances that dominate the glacier record along the northeastern GOA coastline.
Figure 7. Distribution of mean February to August temperatures based on tree-ring-width reconstructions Wiles et al. These data suggest that warm summers caused widespread glacier retreat after , however, February to August temperatures are not exceptionally cold during the widespread advance observed during the 19th century. One possibility is that increased winter precipitation was a key factor, and that these anomalously late LIA maxima owe their occurrence to the combination of Milankovitch forcing, the Dalton Minimum, enhanced volcanic activity, and increased snow accumulation.
This same climatic scenario was first considered and rejected by Tarr and Martin , and proposed again by Miller and Wiles and Calkin New paleoclimate data from several sources now allows us to evaluate this hypothesis. Several paleoclimate reconstructions of NPDV along with wintertime conditions in southern Alaska and southwest Yukon Territory indicate that the GOA coastline experienced relatively high snowfall during the 19th century Figure 8.
A trend of increasing snow-accumulation rates in the Mount Hunter and Mount Logan ice cores began in the early s Figure 8B ; Winski et al. Together, these regional data suggest that increased winter snow accumulation may have contributed to positive mass balances on glaciers throughout southern coastal Alaska.
This conclusion is supported by proxy records in downwind North America, where reconstructions of the wintertime PNA exhibit shifts toward more positive PNA patterns in the early CE s, a teleconnection pattern that also implies a strengthening AL and hence increased winter precipitation in the GOA Figure 8C ; Liu et al. Additionally, oxygen-isotope proxies of paleoclimate from carbonates in lake sediment and from the Mount Logan ice core suggest that an abrupt shift to a stronger AL occurred between the midth and earlyth centuries Figure 8D ; Fisher et al.
In summary, recently published paleo-data support the idea that, starting in the s, the combination of increased winter precipitation and moderately cool summers caused positive mass balances in glaciers bordering the northeastern GOA that resulted in the relatively late timing of their LIA maxima during the closing decades of the 19th century Figures 6 , 8. Figure 8.
Shifts or trends toward a stronger Aleutian Low pressure system preceded the 19th century glacier advance in Coastal Alaska blue box. Up in these graphs reflect a stronger Aleutian Low. The cross-dated outer rings of 30 in situ conifer trees killed by aggrading outwash in front of advancing glacial ice indicate that the La Perouse Glacier in Southeast Alaska advanced to its maximum LIA extent between CE and , and then began to retreat prior to CE Prior to this LIA maximum, the glacier had been in a retracted state since at least CE based on tree-ring dating, radiocarbon-dated soils, and the lags associated with forest succession.
Historical accounts and dendro-glaciological records show that many glaciers surrounding the GOA were also advancing to their LIA-max extents during the s. In contrast, the advances and retreats of a minority of glaciers in the region were partially disconnected from climate by being involved in calving-glacier cycles.
Cooler summers caused by the Dalton Solar Minimum were probably not the sole cause of these s advances because the Dalton Solar Minimum was relatively mild, and previous, stronger solar minima were not associated with comparably widespread and extensive glacial advances. Instead, paleoclimate data from ice cores and lake sediments support the interpretation that increased winter precipitation caused by a strengthening of the AL combined with cool summers to cause late-LIA glacial maxima in the GOA region.
These results highlight the changing climatic sensitivities of glaciers over relatively short time periods and emphasize the collaborative roles of ocean-atmospheric variability and solar cycles in controlling the fluctuations of mountain glaciers.apingifworkgos.gq
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BG designed the research, and conducted the fieldwork, part of the analysis, and wrote the manuscript. DM helped designed the research, and conducted the fieldwork, and helped write the manuscript. GW helped to design the research and conducted interpretation on analysis, and provided comparison data and comments on writing. LA-H helped with interpretation and provided comments on writing. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We thank Gary Thompson and Hans Munich for providing flight service.
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